1380 lines
85 KiB
C
1380 lines
85 KiB
C
/* plock - progressive locks
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*
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* Copyright (C) 2012-2017 Willy Tarreau <w@1wt.eu>
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "atomic-ops.h"
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#ifdef _POSIX_PRIORITY_SCHEDULING
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#include <sched.h>
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#endif
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/* 64 bit */
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#define PLOCK64_RL_1 0x0000000000000004ULL
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#define PLOCK64_RL_2PL 0x00000000FFFFFFF8ULL
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#define PLOCK64_RL_ANY 0x00000000FFFFFFFCULL
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#define PLOCK64_SL_1 0x0000000100000000ULL
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#define PLOCK64_SL_ANY 0x0000000300000000ULL
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#define PLOCK64_WL_1 0x0000000400000000ULL
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#define PLOCK64_WL_2PL 0xFFFFFFF800000000ULL
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#define PLOCK64_WL_ANY 0xFFFFFFFC00000000ULL
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/* 32 bit */
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#define PLOCK32_RL_1 0x00000004
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#define PLOCK32_RL_2PL 0x0000FFF8
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#define PLOCK32_RL_ANY 0x0000FFFC
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#define PLOCK32_SL_1 0x00010000
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#define PLOCK32_SL_ANY 0x00030000
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#define PLOCK32_WL_1 0x00040000
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#define PLOCK32_WL_2PL 0xFFF80000
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#define PLOCK32_WL_ANY 0xFFFC0000
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/* dereferences <*p> as unsigned long without causing aliasing issues */
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#define pl_deref_long(p) ({ volatile unsigned long *__pl_l = (unsigned long *)(p); *__pl_l; })
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/* dereferences <*p> as unsigned int without causing aliasing issues */
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#define pl_deref_int(p) ({ volatile unsigned int *__pl_i = (unsigned int *)(p); *__pl_i; })
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/* This function waits for <lock> to release all bits covered by <mask>, and
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* enforces an exponential backoff using CPU pauses to limit the pollution to
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* the other threads' caches. The progression follows (1.5^N)-1, limited to
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* 16384 iterations, which is way sufficient even for very large numbers of
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* threads. It's possible to disable exponential backoff (EBO) for debugging
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* purposes by setting PLOCK_DISABLE_EBO, in which case the function will be
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* replaced with a simpler macro. This may for example be useful to more
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* easily track callers' CPU usage. The macro was not designed to be used
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* outside of the functions defined here.
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*/
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#if defined(PLOCK_DISABLE_EBO)
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#define pl_wait_unlock_long(lock, mask) \
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({ \
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unsigned long _r; \
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do { \
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pl_cpu_relax(); \
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_r = pl_deref_long(lock); \
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} while (_r & mask); \
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_r; /* return value */ \
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})
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#else
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__attribute__((unused,noinline,no_instrument_function))
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static unsigned long pl_wait_unlock_long(const unsigned long *lock, const unsigned long mask)
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{
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unsigned long ret;
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unsigned int m = 0;
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do {
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unsigned int loops = m;
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#ifdef _POSIX_PRIORITY_SCHEDULING
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if (loops >= 65536) {
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sched_yield();
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loops -= 32768;
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}
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#endif
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for (; loops >= 200; loops -= 10)
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pl_cpu_relax();
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for (; loops >= 1; loops--)
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pl_barrier();
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ret = pl_deref_long(lock);
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if (__builtin_expect(ret & mask, 0) == 0)
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break;
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/* the below produces an exponential growth with loops to lower
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* values and still growing. This allows competing threads to
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* wait different times once the threshold is reached.
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*/
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m = ((m + (m >> 1)) + 2) & 0x3ffff;
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} while (1);
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return ret;
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}
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#endif /* PLOCK_DISABLE_EBO */
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/* This function waits for <lock> to release all bits covered by <mask>, and
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* enforces an exponential backoff using CPU pauses to limit the pollution to
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* the other threads' caches. The progression follows (2^N)-1, limited to 255
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* iterations, which is way sufficient even for very large numbers of threads.
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* The function slightly benefits from size optimization under gcc, but Clang
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* cannot do it, so it's not done here, as it doesn't make a big difference.
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* It is possible to disable exponential backoff (EBO) for debugging purposes
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* by setting PLOCK_DISABLE_EBO, in which case the function will be replaced
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* with a simpler macro. This may for example be useful to more easily track
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* callers' CPU usage. The macro was not designed to be used outside of the
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* functions defined here.
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*/
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#if defined(PLOCK_DISABLE_EBO)
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#define pl_wait_unlock_int(lock, mask) \
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({ \
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unsigned int _r; \
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do { \
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pl_cpu_relax(); \
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_r = pl_deref_int(lock); \
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} while (_r & mask); \
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_r; /* return value */ \
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})
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#else
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__attribute__((unused,noinline,no_instrument_function))
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static unsigned int pl_wait_unlock_int(const unsigned int *lock, const unsigned int mask)
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{
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unsigned int ret;
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unsigned int m = 0;
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do {
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unsigned int loops = m;
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#ifdef _POSIX_PRIORITY_SCHEDULING
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if (loops >= 65536) {
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sched_yield();
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loops -= 32768;
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}
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#endif
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for (; loops >= 200; loops -= 10)
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pl_cpu_relax();
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for (; loops >= 1; loops--)
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pl_barrier();
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ret = pl_deref_int(lock);
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if (__builtin_expect(ret & mask, 0) == 0)
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break;
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/* the below produces an exponential growth with loops to lower
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* values and still growing. This allows competing threads to
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* wait different times once the threshold is reached.
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*/
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m = ((m + (m >> 1)) + 2) & 0x3ffff;
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} while (1);
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return ret;
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}
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#endif /* PLOCK_DISABLE_EBO */
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/* This function waits for <lock> to change from value <prev> and returns the
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* new value. It enforces an exponential backoff using CPU pauses to limit the
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* pollution to the other threads' caches. The progression follows (2^N)-1,
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* limited to 255 iterations, which is way sufficient even for very large
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* numbers of threads. It is designed to be called after a first test which
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* retrieves the previous value, so it starts by waiting. The function slightly
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* benefits from size optimization under gcc, but Clang cannot do it, so it's
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* not done here, as it doesn't make a big difference.
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*/
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__attribute__((unused,noinline,no_instrument_function))
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static unsigned long pl_wait_new_long(const unsigned long *lock, const unsigned long prev)
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{
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unsigned char m = 0;
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unsigned long curr;
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do {
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unsigned char loops = m + 1;
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m = (m << 1) + 1;
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do {
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pl_cpu_relax();
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} while (__builtin_expect(--loops, 0));
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curr = pl_deref_long(lock);
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} while (__builtin_expect(curr == prev, 0));
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return curr;
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}
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/* This function waits for <lock> to change from value <prev> and returns the
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* new value. It enforces an exponential backoff using CPU pauses to limit the
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* pollution to the other threads' caches. The progression follows (2^N)-1,
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* limited to 255 iterations, which is way sufficient even for very large
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* numbers of threads. It is designed to be called after a first test which
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* retrieves the previous value, so it starts by waiting. The function slightly
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* benefits from size optimization under gcc, but Clang cannot do it, so it's
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* not done here, as it doesn't make a big difference.
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*/
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__attribute__((unused,noinline,no_instrument_function))
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static unsigned int pl_wait_new_int(const unsigned int *lock, const unsigned int prev)
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{
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unsigned char m = 0;
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unsigned int curr;
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do {
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unsigned char loops = m + 1;
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m = (m << 1) + 1;
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do {
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pl_cpu_relax();
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} while (__builtin_expect(--loops, 0));
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curr = pl_deref_int(lock);
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} while (__builtin_expect(curr == prev, 0));
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return curr;
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}
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/* request shared read access (R), return non-zero on success, otherwise 0 */
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#define pl_try_r(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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register unsigned long __pl_r = pl_deref_long(lock) & PLOCK64_WL_ANY; \
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pl_barrier(); \
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if (!__builtin_expect(__pl_r, 0)) { \
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__pl_r = pl_xadd((lock), PLOCK64_RL_1) & PLOCK64_WL_ANY; \
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if (__builtin_expect(__pl_r, 0)) \
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pl_sub((lock), PLOCK64_RL_1); \
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} \
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!__pl_r; /* return value */ \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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register unsigned int __pl_r = pl_deref_int(lock) & PLOCK32_WL_ANY; \
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pl_barrier(); \
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if (!__builtin_expect(__pl_r, 0)) { \
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__pl_r = pl_xadd((lock), PLOCK32_RL_1) & PLOCK32_WL_ANY; \
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if (__builtin_expect(__pl_r, 0)) \
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pl_sub((lock), PLOCK32_RL_1); \
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} \
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!__pl_r; /* return value */ \
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}) : ({ \
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void __unsupported_argument_size_for_pl_try_r__(char *,int); \
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if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
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__unsupported_argument_size_for_pl_try_r__(__FILE__,__LINE__); \
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0; \
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}) \
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)
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/* request shared read access (R) and wait for it. In order not to disturb a W
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* lock waiting for all readers to leave, we first check if a W lock is held
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* before trying to claim the R lock.
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*/
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#define pl_take_r(lock) \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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register unsigned long *__lk_r = (unsigned long *)(lock); \
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register unsigned long __set_r = PLOCK64_RL_1; \
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register unsigned long __msk_r = PLOCK64_WL_ANY; \
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while (1) { \
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if (__builtin_expect(pl_deref_long(__lk_r) & __msk_r, 0)) \
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pl_wait_unlock_long(__lk_r, __msk_r); \
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if (!__builtin_expect(pl_xadd(__lk_r, __set_r) & __msk_r, 0)) \
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break; \
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pl_sub(__lk_r, __set_r); \
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} \
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pl_barrier(); \
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0; \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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register unsigned int *__lk_r = (unsigned int *)(lock); \
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register unsigned int __set_r = PLOCK32_RL_1; \
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register unsigned int __msk_r = PLOCK32_WL_ANY; \
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while (1) { \
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if (__builtin_expect(pl_deref_int(__lk_r) & __msk_r, 0)) \
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pl_wait_unlock_int(__lk_r, __msk_r); \
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if (!__builtin_expect(pl_xadd(__lk_r, __set_r) & __msk_r, 0)) \
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break; \
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pl_sub(__lk_r, __set_r); \
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} \
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pl_barrier(); \
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0; \
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}) : ({ \
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void __unsupported_argument_size_for_pl_take_r__(char *,int); \
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if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
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__unsupported_argument_size_for_pl_take_r__(__FILE__,__LINE__); \
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0; \
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})
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/* release the read access (R) lock */
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#define pl_drop_r(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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pl_barrier(); \
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pl_sub(lock, PLOCK64_RL_1); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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pl_barrier(); \
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pl_sub(lock, PLOCK32_RL_1); \
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}) : ({ \
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void __unsupported_argument_size_for_pl_drop_r__(char *,int); \
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if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
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__unsupported_argument_size_for_pl_drop_r__(__FILE__,__LINE__); \
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}) \
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)
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/* request a seek access (S), return non-zero on success, otherwise 0 */
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#define pl_try_s(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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register unsigned long __pl_r = pl_deref_long(lock); \
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pl_barrier(); \
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if (!__builtin_expect(__pl_r & (PLOCK64_WL_ANY | PLOCK64_SL_ANY), 0)) { \
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__pl_r = pl_xadd((lock), PLOCK64_SL_1 | PLOCK64_RL_1) & \
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(PLOCK64_WL_ANY | PLOCK64_SL_ANY); \
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if (__builtin_expect(__pl_r, 0)) \
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pl_sub((lock), PLOCK64_SL_1 | PLOCK64_RL_1); \
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} \
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!__pl_r; /* return value */ \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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register unsigned int __pl_r = pl_deref_int(lock); \
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pl_barrier(); \
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if (!__builtin_expect(__pl_r & (PLOCK32_WL_ANY | PLOCK32_SL_ANY), 0)) { \
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__pl_r = pl_xadd((lock), PLOCK32_SL_1 | PLOCK32_RL_1) & \
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(PLOCK32_WL_ANY | PLOCK32_SL_ANY); \
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if (__builtin_expect(__pl_r, 0)) \
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pl_sub((lock), PLOCK32_SL_1 | PLOCK32_RL_1); \
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} \
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!__pl_r; /* return value */ \
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}) : ({ \
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void __unsupported_argument_size_for_pl_try_s__(char *,int); \
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if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
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__unsupported_argument_size_for_pl_try_s__(__FILE__,__LINE__); \
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0; \
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}) \
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)
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/* request a seek access (S) and wait for it. The lock is immediately claimed,
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* and only upon failure an exponential backoff is used. S locks rarely compete
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* with W locks so S will generally not disturb W. As the S lock may be used as
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* a spinlock, it's important to grab it as fast as possible.
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*/
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#define pl_take_s(lock) \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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register unsigned long *__lk_r = (unsigned long *)(lock); \
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register unsigned long __set_r = PLOCK64_SL_1 | PLOCK64_RL_1; \
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register unsigned long __msk_r = PLOCK64_WL_ANY | PLOCK64_SL_ANY; \
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while (1) { \
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if (!__builtin_expect(pl_xadd(__lk_r, __set_r) & __msk_r, 0)) \
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break; \
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pl_sub(__lk_r, __set_r); \
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pl_wait_unlock_long(__lk_r, __msk_r); \
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} \
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pl_barrier(); \
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0; \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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register unsigned int *__lk_r = (unsigned int *)(lock); \
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register unsigned int __set_r = PLOCK32_SL_1 | PLOCK32_RL_1; \
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register unsigned int __msk_r = PLOCK32_WL_ANY | PLOCK32_SL_ANY; \
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while (1) { \
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if (!__builtin_expect(pl_xadd(__lk_r, __set_r) & __msk_r, 0)) \
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break; \
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pl_sub(__lk_r, __set_r); \
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pl_wait_unlock_int(__lk_r, __msk_r); \
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} \
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pl_barrier(); \
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0; \
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}) : ({ \
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void __unsupported_argument_size_for_pl_take_s__(char *,int); \
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if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
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__unsupported_argument_size_for_pl_take_s__(__FILE__,__LINE__); \
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0; \
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})
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/* release the seek access (S) lock */
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#define pl_drop_s(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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pl_barrier(); \
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pl_sub(lock, PLOCK64_SL_1 + PLOCK64_RL_1); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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pl_barrier(); \
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pl_sub(lock, PLOCK32_SL_1 + PLOCK32_RL_1); \
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}) : ({ \
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void __unsupported_argument_size_for_pl_drop_s__(char *,int); \
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if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
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__unsupported_argument_size_for_pl_drop_s__(__FILE__,__LINE__); \
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}) \
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)
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/* drop the S lock and go back to the R lock */
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#define pl_stor(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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pl_barrier(); \
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pl_sub(lock, PLOCK64_SL_1); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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pl_barrier(); \
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pl_sub(lock, PLOCK32_SL_1); \
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}) : ({ \
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void __unsupported_argument_size_for_pl_stor__(char *,int); \
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if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
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__unsupported_argument_size_for_pl_stor__(__FILE__,__LINE__); \
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}) \
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)
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/* take the W lock under the S lock */
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#define pl_stow(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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register unsigned long __pl_r = pl_xadd((lock), PLOCK64_WL_1); \
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while ((__pl_r & PLOCK64_RL_ANY) != PLOCK64_RL_1) \
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__pl_r = pl_deref_long(lock); \
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pl_barrier(); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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register unsigned int __pl_r = pl_xadd((lock), PLOCK32_WL_1); \
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while ((__pl_r & PLOCK32_RL_ANY) != PLOCK32_RL_1) \
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__pl_r = pl_deref_int(lock); \
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pl_barrier(); \
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}) : ({ \
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void __unsupported_argument_size_for_pl_stow__(char *,int); \
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if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
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__unsupported_argument_size_for_pl_stow__(__FILE__,__LINE__); \
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}) \
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)
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/* drop the W lock and go back to the S lock */
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#define pl_wtos(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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pl_barrier(); \
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pl_sub(lock, PLOCK64_WL_1); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
pl_barrier(); \
|
|
pl_sub(lock, PLOCK32_WL_1); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_wtos__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_wtos__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* drop the W lock and go back to the R lock */
|
|
#define pl_wtor(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
pl_barrier(); \
|
|
pl_sub(lock, PLOCK64_WL_1 | PLOCK64_SL_1); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
pl_barrier(); \
|
|
pl_sub(lock, PLOCK32_WL_1 | PLOCK32_SL_1); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_wtor__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_wtor__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* request a write access (W), return non-zero on success, otherwise 0.
|
|
*
|
|
* Below there is something important : by taking both W and S, we will cause
|
|
* an overflow of W at 4/5 of the maximum value that can be stored into W due
|
|
* to the fact that S is 2 bits, so we're effectively adding 5 to the word
|
|
* composed by W:S. But for all words multiple of 4 bits, the maximum value is
|
|
* multiple of 15 thus of 5. So the largest value we can store with all bits
|
|
* set to one will be met by adding 5, and then adding 5 again will place value
|
|
* 1 in W and value 0 in S, so we never leave W with 0. Also, even upon such an
|
|
* overflow, there's no risk to confuse it with an atomic lock because R is not
|
|
* null since it will not have overflown. For 32-bit locks, this situation
|
|
* happens when exactly 13108 threads try to grab the lock at once, W=1, S=0
|
|
* and R=13108. For 64-bit locks, it happens at 858993460 concurrent writers
|
|
* where W=1, S=0 and R=858993460.
|
|
*/
|
|
#define pl_try_w(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long __pl_r = pl_deref_long(lock); \
|
|
pl_barrier(); \
|
|
if (!__builtin_expect(__pl_r & (PLOCK64_WL_ANY | PLOCK64_SL_ANY), 0)) { \
|
|
__pl_r = pl_xadd((lock), PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
|
|
if (__builtin_expect(__pl_r & (PLOCK64_WL_ANY | PLOCK64_SL_ANY), 0)) { \
|
|
/* a writer, seeker or atomic is present, let's leave */ \
|
|
pl_sub((lock), PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
|
|
__pl_r &= (PLOCK64_WL_ANY | PLOCK64_SL_ANY); /* return value */\
|
|
} else { \
|
|
/* wait for all other readers to leave */ \
|
|
while (__pl_r) \
|
|
__pl_r = pl_deref_long(lock) - \
|
|
(PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
|
|
} \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int __pl_r = pl_deref_int(lock); \
|
|
pl_barrier(); \
|
|
if (!__builtin_expect(__pl_r & (PLOCK32_WL_ANY | PLOCK32_SL_ANY), 0)) { \
|
|
__pl_r = pl_xadd((lock), PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
|
|
if (__builtin_expect(__pl_r & (PLOCK32_WL_ANY | PLOCK32_SL_ANY), 0)) { \
|
|
/* a writer, seeker or atomic is present, let's leave */ \
|
|
pl_sub((lock), PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
|
|
__pl_r &= (PLOCK32_WL_ANY | PLOCK32_SL_ANY); /* return value */\
|
|
} else { \
|
|
/* wait for all other readers to leave */ \
|
|
while (__pl_r) \
|
|
__pl_r = pl_deref_int(lock) - \
|
|
(PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
|
|
} \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_try_w__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_try_w__(__FILE__,__LINE__); \
|
|
0; \
|
|
}) \
|
|
)
|
|
|
|
/* request a write access (W) and wait for it. The lock is immediately claimed,
|
|
* and only upon failure an exponential backoff is used.
|
|
*/
|
|
#define pl_take_w(lock) \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __set_r = PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1; \
|
|
register unsigned long __msk_r = PLOCK64_WL_ANY | PLOCK64_SL_ANY; \
|
|
register unsigned long __pl_r; \
|
|
while (1) { \
|
|
__pl_r = pl_xadd(__lk_r, __set_r); \
|
|
if (!__builtin_expect(__pl_r & __msk_r, 0)) \
|
|
break; \
|
|
pl_sub(__lk_r, __set_r); \
|
|
__pl_r = pl_wait_unlock_long(__lk_r, __msk_r); \
|
|
} \
|
|
/* wait for all other readers to leave */ \
|
|
while (__builtin_expect(__pl_r, 0)) \
|
|
__pl_r = pl_deref_long(__lk_r) - __set_r; \
|
|
pl_barrier(); \
|
|
0; \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __set_r = PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1; \
|
|
register unsigned int __msk_r = PLOCK32_WL_ANY | PLOCK32_SL_ANY; \
|
|
register unsigned int __pl_r; \
|
|
while (1) { \
|
|
__pl_r = pl_xadd(__lk_r, __set_r); \
|
|
if (!__builtin_expect(__pl_r & __msk_r, 0)) \
|
|
break; \
|
|
pl_sub(__lk_r, __set_r); \
|
|
__pl_r = pl_wait_unlock_int(__lk_r, __msk_r); \
|
|
} \
|
|
/* wait for all other readers to leave */ \
|
|
while (__builtin_expect(__pl_r, 0)) \
|
|
__pl_r = pl_deref_int(__lk_r) - __set_r; \
|
|
pl_barrier(); \
|
|
0; \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_take_w__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_take_w__(__FILE__,__LINE__); \
|
|
0; \
|
|
})
|
|
|
|
/* drop the write (W) lock entirely */
|
|
#define pl_drop_w(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
pl_barrier(); \
|
|
pl_sub(lock, PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
pl_barrier(); \
|
|
pl_sub(lock, PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_drop_w__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_drop_w__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* Try to upgrade from R to S, return non-zero on success, otherwise 0.
|
|
* This lock will fail if S or W are already held. In case of failure to grab
|
|
* the lock, it MUST NOT be retried without first dropping R, or it may never
|
|
* complete due to S waiting for R to leave before upgrading to W.
|
|
*/
|
|
#define pl_try_rtos(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long __pl_r = pl_deref_long(lock); \
|
|
pl_barrier(); \
|
|
if (!__builtin_expect(__pl_r & (PLOCK64_WL_ANY | PLOCK64_SL_ANY), 0)) { \
|
|
__pl_r = pl_xadd((lock), PLOCK64_SL_1) & \
|
|
(PLOCK64_WL_ANY | PLOCK64_SL_ANY); \
|
|
if (__builtin_expect(__pl_r, 0)) \
|
|
pl_sub((lock), PLOCK64_SL_1); \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int __pl_r = pl_deref_int(lock); \
|
|
pl_barrier(); \
|
|
if (!__builtin_expect(__pl_r & (PLOCK32_WL_ANY | PLOCK32_SL_ANY), 0)) { \
|
|
__pl_r = pl_xadd((lock), PLOCK32_SL_1) & \
|
|
(PLOCK32_WL_ANY | PLOCK32_SL_ANY); \
|
|
if (__builtin_expect(__pl_r, 0)) \
|
|
pl_sub((lock), PLOCK32_SL_1); \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_try_rtos__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_try_rtos__(__FILE__,__LINE__); \
|
|
0; \
|
|
}) \
|
|
)
|
|
|
|
|
|
/* Try to upgrade from R to W, return non-zero on success, otherwise 0.
|
|
* This lock will fail if S or W are already held. In case of failure to grab
|
|
* the lock, it MUST NOT be retried without first dropping R, or it may never
|
|
* complete due to S waiting for R to leave before upgrading to W. It waits for
|
|
* the last readers to leave.
|
|
*/
|
|
#define pl_try_rtow(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __set_r = PLOCK64_WL_1 | PLOCK64_SL_1; \
|
|
register unsigned long __msk_r = PLOCK64_WL_ANY | PLOCK64_SL_ANY; \
|
|
register unsigned long __pl_r; \
|
|
pl_barrier(); \
|
|
while (1) { \
|
|
__pl_r = pl_xadd(__lk_r, __set_r); \
|
|
if (__builtin_expect(__pl_r & __msk_r, 0)) { \
|
|
if (pl_xadd(__lk_r, - __set_r)) \
|
|
break; /* the caller needs to drop the lock now */ \
|
|
continue; /* lock was released, try again */ \
|
|
} \
|
|
/* ok we're the only writer, wait for readers to leave */ \
|
|
while (__builtin_expect(__pl_r, 0)) \
|
|
__pl_r = pl_deref_long(__lk_r) - (PLOCK64_WL_1|PLOCK64_SL_1|PLOCK64_RL_1); \
|
|
/* now return with __pl_r = 0 */ \
|
|
break; \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __set_r = PLOCK32_WL_1 | PLOCK32_SL_1; \
|
|
register unsigned int __msk_r = PLOCK32_WL_ANY | PLOCK32_SL_ANY; \
|
|
register unsigned int __pl_r; \
|
|
pl_barrier(); \
|
|
while (1) { \
|
|
__pl_r = pl_xadd(__lk_r, __set_r); \
|
|
if (__builtin_expect(__pl_r & __msk_r, 0)) { \
|
|
if (pl_xadd(__lk_r, - __set_r)) \
|
|
break; /* the caller needs to drop the lock now */ \
|
|
continue; /* lock was released, try again */ \
|
|
} \
|
|
/* ok we're the only writer, wait for readers to leave */ \
|
|
while (__builtin_expect(__pl_r, 0)) \
|
|
__pl_r = pl_deref_int(__lk_r) - (PLOCK32_WL_1|PLOCK32_SL_1|PLOCK32_RL_1); \
|
|
/* now return with __pl_r = 0 */ \
|
|
break; \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_try_rtow__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_try_rtow__(__FILE__,__LINE__); \
|
|
0; \
|
|
}) \
|
|
)
|
|
|
|
|
|
/* request atomic write access (A), return non-zero on success, otherwise 0.
|
|
* It's a bit tricky as we only use the W bits for this and want to distinguish
|
|
* between other atomic users and regular lock users. We have to give up if an
|
|
* S lock appears. It's possible that such a lock stays hidden in the W bits
|
|
* after an overflow, but in this case R is still held, ensuring we stay in the
|
|
* loop until we discover the conflict. The lock only return successfully if all
|
|
* readers are gone (or converted to A).
|
|
*/
|
|
#define pl_try_a(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long __pl_r = pl_deref_long(lock) & PLOCK64_SL_ANY; \
|
|
pl_barrier(); \
|
|
if (!__builtin_expect(__pl_r, 0)) { \
|
|
__pl_r = pl_xadd((lock), PLOCK64_WL_1); \
|
|
while (1) { \
|
|
if (__builtin_expect(__pl_r & PLOCK64_SL_ANY, 0)) { \
|
|
pl_sub((lock), PLOCK64_WL_1); \
|
|
break; /* return !__pl_r */ \
|
|
} \
|
|
__pl_r &= PLOCK64_RL_ANY; \
|
|
if (!__builtin_expect(__pl_r, 0)) \
|
|
break; /* return !__pl_r */ \
|
|
__pl_r = pl_deref_long(lock); \
|
|
} \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int __pl_r = pl_deref_int(lock) & PLOCK32_SL_ANY; \
|
|
pl_barrier(); \
|
|
if (!__builtin_expect(__pl_r, 0)) { \
|
|
__pl_r = pl_xadd((lock), PLOCK32_WL_1); \
|
|
while (1) { \
|
|
if (__builtin_expect(__pl_r & PLOCK32_SL_ANY, 0)) { \
|
|
pl_sub((lock), PLOCK32_WL_1); \
|
|
break; /* return !__pl_r */ \
|
|
} \
|
|
__pl_r &= PLOCK32_RL_ANY; \
|
|
if (!__builtin_expect(__pl_r, 0)) \
|
|
break; /* return !__pl_r */ \
|
|
__pl_r = pl_deref_int(lock); \
|
|
} \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_try_a__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_try_a__(__FILE__,__LINE__); \
|
|
0; \
|
|
}) \
|
|
)
|
|
|
|
/* request atomic write access (A) and wait for it. See comments in pl_try_a() for
|
|
* explanations.
|
|
*/
|
|
#define pl_take_a(lock) \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __set_r = PLOCK64_WL_1; \
|
|
register unsigned long __msk_r = PLOCK64_SL_ANY; \
|
|
register unsigned long __pl_r; \
|
|
__pl_r = pl_xadd(__lk_r, __set_r); \
|
|
while (__builtin_expect(__pl_r & PLOCK64_RL_ANY, 0)) { \
|
|
if (__builtin_expect(__pl_r & __msk_r, 0)) { \
|
|
pl_sub(__lk_r, __set_r); \
|
|
pl_wait_unlock_long(__lk_r, __msk_r); \
|
|
__pl_r = pl_xadd(__lk_r, __set_r); \
|
|
continue; \
|
|
} \
|
|
/* wait for all readers to leave or upgrade */ \
|
|
pl_cpu_relax(); pl_cpu_relax(); pl_cpu_relax(); \
|
|
__pl_r = pl_deref_long(lock); \
|
|
} \
|
|
pl_barrier(); \
|
|
0; \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __set_r = PLOCK32_WL_1; \
|
|
register unsigned int __msk_r = PLOCK32_SL_ANY; \
|
|
register unsigned int __pl_r; \
|
|
__pl_r = pl_xadd(__lk_r, __set_r); \
|
|
while (__builtin_expect(__pl_r & PLOCK32_RL_ANY, 0)) { \
|
|
if (__builtin_expect(__pl_r & __msk_r, 0)) { \
|
|
pl_sub(__lk_r, __set_r); \
|
|
pl_wait_unlock_int(__lk_r, __msk_r); \
|
|
__pl_r = pl_xadd(__lk_r, __set_r); \
|
|
continue; \
|
|
} \
|
|
/* wait for all readers to leave or upgrade */ \
|
|
pl_cpu_relax(); pl_cpu_relax(); pl_cpu_relax(); \
|
|
__pl_r = pl_deref_int(lock); \
|
|
} \
|
|
pl_barrier(); \
|
|
0; \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_take_a__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_take_a__(__FILE__,__LINE__); \
|
|
0; \
|
|
})
|
|
|
|
/* release atomic write access (A) lock */
|
|
#define pl_drop_a(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
pl_barrier(); \
|
|
pl_sub(lock, PLOCK64_WL_1); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
pl_barrier(); \
|
|
pl_sub(lock, PLOCK32_WL_1); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_drop_a__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_drop_a__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* Downgrade A to R. Inc(R), dec(W) then wait for W==0 */
|
|
#define pl_ator(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __set_r = PLOCK64_RL_1 - PLOCK64_WL_1; \
|
|
register unsigned long __msk_r = PLOCK64_WL_ANY; \
|
|
register unsigned long __pl_r = pl_xadd(__lk_r, __set_r) + __set_r; \
|
|
while (__builtin_expect(__pl_r & __msk_r, 0)) { \
|
|
__pl_r = pl_wait_unlock_long(__lk_r, __msk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __set_r = PLOCK32_RL_1 - PLOCK32_WL_1; \
|
|
register unsigned int __msk_r = PLOCK32_WL_ANY; \
|
|
register unsigned int __pl_r = pl_xadd(__lk_r, __set_r) + __set_r; \
|
|
while (__builtin_expect(__pl_r & __msk_r, 0)) { \
|
|
__pl_r = pl_wait_unlock_int(__lk_r, __msk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_ator__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_ator__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* Try to upgrade from R to A, return non-zero on success, otherwise 0.
|
|
* This lock will fail if S is held or appears while waiting (typically due to
|
|
* a previous grab that was disguised as a W due to an overflow). In case of
|
|
* failure to grab the lock, it MUST NOT be retried without first dropping R,
|
|
* or it may never complete due to S waiting for R to leave before upgrading
|
|
* to W. The lock succeeds once there's no more R (ie all of them have either
|
|
* completed or were turned to A).
|
|
*/
|
|
#define pl_try_rtoa(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long __pl_r = pl_deref_long(lock) & PLOCK64_SL_ANY; \
|
|
pl_barrier(); \
|
|
if (!__builtin_expect(__pl_r, 0)) { \
|
|
__pl_r = pl_xadd((lock), PLOCK64_WL_1 - PLOCK64_RL_1); \
|
|
while (1) { \
|
|
if (__builtin_expect(__pl_r & PLOCK64_SL_ANY, 0)) { \
|
|
pl_sub((lock), PLOCK64_WL_1 - PLOCK64_RL_1); \
|
|
break; /* return !__pl_r */ \
|
|
} \
|
|
__pl_r &= PLOCK64_RL_ANY; \
|
|
if (!__builtin_expect(__pl_r, 0)) \
|
|
break; /* return !__pl_r */ \
|
|
__pl_r = pl_deref_long(lock); \
|
|
} \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int __pl_r = pl_deref_int(lock) & PLOCK32_SL_ANY; \
|
|
pl_barrier(); \
|
|
if (!__builtin_expect(__pl_r, 0)) { \
|
|
__pl_r = pl_xadd((lock), PLOCK32_WL_1 - PLOCK32_RL_1); \
|
|
while (1) { \
|
|
if (__builtin_expect(__pl_r & PLOCK32_SL_ANY, 0)) { \
|
|
pl_sub((lock), PLOCK32_WL_1 - PLOCK32_RL_1); \
|
|
break; /* return !__pl_r */ \
|
|
} \
|
|
__pl_r &= PLOCK32_RL_ANY; \
|
|
if (!__builtin_expect(__pl_r, 0)) \
|
|
break; /* return !__pl_r */ \
|
|
__pl_r = pl_deref_int(lock); \
|
|
} \
|
|
} \
|
|
!__pl_r; /* return value */ \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_try_rtoa__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_try_rtoa__(__FILE__,__LINE__); \
|
|
0; \
|
|
}) \
|
|
)
|
|
|
|
|
|
/*
|
|
* The following operations cover the multiple writers model : U->R->J->C->A
|
|
*/
|
|
|
|
|
|
/* Upgrade R to J. Inc(W) then wait for R==W or S != 0 */
|
|
#define pl_rtoj(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __pl_r = pl_xadd(__lk_r, PLOCK64_WL_1) + PLOCK64_WL_1; \
|
|
register unsigned char __m = 0; \
|
|
while (!(__pl_r & PLOCK64_SL_ANY) && \
|
|
(__pl_r / PLOCK64_WL_1 != (__pl_r & PLOCK64_RL_ANY) / PLOCK64_RL_1)) { \
|
|
unsigned char __loops = __m + 1; \
|
|
__m = (__m << 1) + 1; \
|
|
do { \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
} while (--__loops); \
|
|
__pl_r = pl_deref_long(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __pl_r = pl_xadd(__lk_r, PLOCK32_WL_1) + PLOCK32_WL_1; \
|
|
register unsigned char __m = 0; \
|
|
while (!(__pl_r & PLOCK32_SL_ANY) && \
|
|
(__pl_r / PLOCK32_WL_1 != (__pl_r & PLOCK32_RL_ANY) / PLOCK32_RL_1)) { \
|
|
unsigned char __loops = __m + 1; \
|
|
__m = (__m << 1) + 1; \
|
|
do { \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
} while (--__loops); \
|
|
__pl_r = pl_deref_int(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_rtoj__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_rtoj__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* Upgrade J to C. Set S. Only one thread needs to do it though it's idempotent */
|
|
#define pl_jtoc(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __pl_r = pl_deref_long(__lk_r); \
|
|
if (!(__pl_r & PLOCK64_SL_ANY)) \
|
|
pl_or(__lk_r, PLOCK64_SL_1); \
|
|
pl_barrier(); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __pl_r = pl_deref_int(__lk_r); \
|
|
if (!(__pl_r & PLOCK32_SL_ANY)) \
|
|
pl_or(__lk_r, PLOCK32_SL_1); \
|
|
pl_barrier(); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_jtoc__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_jtoc__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* Upgrade R to C. Inc(W) then wait for R==W or S != 0 */
|
|
#define pl_rtoc(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __pl_r = pl_xadd(__lk_r, PLOCK64_WL_1) + PLOCK64_WL_1; \
|
|
register unsigned char __m = 0; \
|
|
while (__builtin_expect(!(__pl_r & PLOCK64_SL_ANY), 0)) { \
|
|
unsigned char __loops; \
|
|
if (__pl_r / PLOCK64_WL_1 == (__pl_r & PLOCK64_RL_ANY) / PLOCK64_RL_1) { \
|
|
pl_or(__lk_r, PLOCK64_SL_1); \
|
|
break; \
|
|
} \
|
|
__loops = __m + 1; \
|
|
__m = (__m << 1) + 1; \
|
|
do { \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
} while (--__loops); \
|
|
__pl_r = pl_deref_long(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __pl_r = pl_xadd(__lk_r, PLOCK32_WL_1) + PLOCK32_WL_1; \
|
|
register unsigned char __m = 0; \
|
|
while (__builtin_expect(!(__pl_r & PLOCK32_SL_ANY), 0)) { \
|
|
unsigned char __loops; \
|
|
if (__pl_r / PLOCK32_WL_1 == (__pl_r & PLOCK32_RL_ANY) / PLOCK32_RL_1) { \
|
|
pl_or(__lk_r, PLOCK32_SL_1); \
|
|
break; \
|
|
} \
|
|
__loops = __m + 1; \
|
|
__m = (__m << 1) + 1; \
|
|
do { \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
} while (--__loops); \
|
|
__pl_r = pl_deref_int(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_rtoj__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_rtoj__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* Drop the claim (C) lock : R--,W-- then clear S if !R */
|
|
#define pl_drop_c(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __set_r = - PLOCK64_RL_1 - PLOCK64_WL_1; \
|
|
register unsigned long __pl_r = pl_xadd(__lk_r, __set_r) + __set_r; \
|
|
if (!(__pl_r & PLOCK64_RL_ANY)) \
|
|
pl_and(__lk_r, ~PLOCK64_SL_1); \
|
|
pl_barrier(); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __set_r = - PLOCK32_RL_1 - PLOCK32_WL_1; \
|
|
register unsigned int __pl_r = pl_xadd(__lk_r, __set_r) + __set_r; \
|
|
if (!(__pl_r & PLOCK32_RL_ANY)) \
|
|
pl_and(__lk_r, ~PLOCK32_SL_1); \
|
|
pl_barrier(); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_drop_c__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_drop_c__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* Upgrade C to A. R-- then wait for !S or clear S if !R */
|
|
#define pl_ctoa(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __pl_r = pl_xadd(__lk_r, -PLOCK64_RL_1) - PLOCK64_RL_1; \
|
|
while (__pl_r & PLOCK64_SL_ANY) { \
|
|
if (!(__pl_r & PLOCK64_RL_ANY)) { \
|
|
pl_and(__lk_r, ~PLOCK64_SL_1); \
|
|
break; \
|
|
} \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
__pl_r = pl_deref_long(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __pl_r = pl_xadd(__lk_r, -PLOCK32_RL_1) - PLOCK32_RL_1; \
|
|
while (__pl_r & PLOCK32_SL_ANY) { \
|
|
if (!(__pl_r & PLOCK32_RL_ANY)) { \
|
|
pl_and(__lk_r, ~PLOCK32_SL_1); \
|
|
break; \
|
|
} \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
__pl_r = pl_deref_int(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_ctoa__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_ctoa__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* downgrade the atomic write access lock (A) to join (J) */
|
|
#define pl_atoj(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
pl_barrier(); \
|
|
pl_add(lock, PLOCK64_RL_1); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
pl_barrier(); \
|
|
pl_add(lock, PLOCK32_RL_1); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_atoj__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_atoj__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/* Returns non-zero if the thread calling it is the last writer, otherwise zero. It is
|
|
* designed to be called before pl_drop_j(), pl_drop_c() or pl_drop_a() for operations
|
|
* which need to be called only once.
|
|
*/
|
|
#define pl_last_writer(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
!(pl_deref_long(lock) & PLOCK64_WL_2PL); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
!(pl_deref_int(lock) & PLOCK32_WL_2PL); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_last_j__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_last_j__(__FILE__,__LINE__); \
|
|
0; \
|
|
}) \
|
|
)
|
|
|
|
/* attempt to get an exclusive write access via the J lock and wait for it.
|
|
* Only one thread may succeed in this operation. It will not conflict with
|
|
* other users and will first wait for all writers to leave, then for all
|
|
* readers to leave before starting. This offers a solution to obtain an
|
|
* exclusive access to a shared resource in the R/J/C/A model. A concurrent
|
|
* take_a() will wait for this one to finish first. Using a CAS instead of XADD
|
|
* should make the operation converge slightly faster. Returns non-zero on
|
|
* success otherwise 0.
|
|
*/
|
|
#define pl_try_j(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __set_r = PLOCK64_WL_1 | PLOCK64_RL_1; \
|
|
register unsigned long __msk_r = PLOCK64_WL_ANY; \
|
|
register unsigned long __pl_r; \
|
|
register unsigned char __m; \
|
|
pl_wait_unlock_long(__lk_r, __msk_r); \
|
|
__pl_r = pl_xadd(__lk_r, __set_r) + __set_r; \
|
|
/* wait for all other readers to leave */ \
|
|
__m = 0; \
|
|
while (__builtin_expect(__pl_r & PLOCK64_RL_2PL, 0)) { \
|
|
unsigned char __loops; \
|
|
/* give up on other writers */ \
|
|
if (__builtin_expect(__pl_r & PLOCK64_WL_2PL, 0)) { \
|
|
pl_sub(__lk_r, __set_r); \
|
|
__pl_r = 0; /* failed to get the lock */ \
|
|
break; \
|
|
} \
|
|
__loops = __m + 1; \
|
|
__m = (__m << 1) + 1; \
|
|
do { \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
} while (--__loops); \
|
|
__pl_r = pl_deref_long(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
__pl_r; /* return value, cannot be null on success */ \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __set_r = PLOCK32_WL_1 | PLOCK32_RL_1; \
|
|
register unsigned int __msk_r = PLOCK32_WL_ANY; \
|
|
register unsigned int __pl_r; \
|
|
register unsigned char __m; \
|
|
pl_wait_unlock_int(__lk_r, __msk_r); \
|
|
__pl_r = pl_xadd(__lk_r, __set_r) + __set_r; \
|
|
/* wait for all other readers to leave */ \
|
|
__m = 0; \
|
|
while (__builtin_expect(__pl_r & PLOCK32_RL_2PL, 0)) { \
|
|
unsigned char __loops; \
|
|
/* but rollback on other writers */ \
|
|
if (__builtin_expect(__pl_r & PLOCK32_WL_2PL, 0)) { \
|
|
pl_sub(__lk_r, __set_r); \
|
|
__pl_r = 0; /* failed to get the lock */ \
|
|
break; \
|
|
} \
|
|
__loops = __m + 1; \
|
|
__m = (__m << 1) + 1; \
|
|
do { \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
} while (--__loops); \
|
|
__pl_r = pl_deref_int(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
__pl_r; /* return value, cannot be null on success */ \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_try_j__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_try_j__(__FILE__,__LINE__); \
|
|
0; \
|
|
}) \
|
|
)
|
|
|
|
/* request an exclusive write access via the J lock and wait for it. Only one
|
|
* thread may succeed in this operation. It will not conflict with other users
|
|
* and will first wait for all writers to leave, then for all readers to leave
|
|
* before starting. This offers a solution to obtain an exclusive access to a
|
|
* shared resource in the R/J/C/A model. A concurrent take_a() will wait for
|
|
* this one to finish first. Using a CAS instead of XADD should make the
|
|
* operation converge slightly faster.
|
|
*/
|
|
#define pl_take_j(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
__label__ __retry; \
|
|
register unsigned long *__lk_r = (unsigned long *)(lock); \
|
|
register unsigned long __set_r = PLOCK64_WL_1 | PLOCK64_RL_1; \
|
|
register unsigned long __msk_r = PLOCK64_WL_ANY; \
|
|
register unsigned long __pl_r; \
|
|
register unsigned char __m; \
|
|
__retry: \
|
|
pl_wait_unlock_long(__lk_r, __msk_r); \
|
|
__pl_r = pl_xadd(__lk_r, __set_r) + __set_r; \
|
|
/* wait for all other readers to leave */ \
|
|
__m = 0; \
|
|
while (__builtin_expect(__pl_r & PLOCK64_RL_2PL, 0)) { \
|
|
unsigned char __loops; \
|
|
/* but rollback on other writers */ \
|
|
if (__builtin_expect(__pl_r & PLOCK64_WL_2PL, 0)) { \
|
|
pl_sub(__lk_r, __set_r); \
|
|
goto __retry; \
|
|
} \
|
|
__loops = __m + 1; \
|
|
__m = (__m << 1) + 1; \
|
|
do { \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
} while (--__loops); \
|
|
__pl_r = pl_deref_long(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
0; \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
__label__ __retry; \
|
|
register unsigned int *__lk_r = (unsigned int *)(lock); \
|
|
register unsigned int __set_r = PLOCK32_WL_1 | PLOCK32_RL_1; \
|
|
register unsigned int __msk_r = PLOCK32_WL_ANY; \
|
|
register unsigned int __pl_r; \
|
|
register unsigned char __m; \
|
|
__retry: \
|
|
pl_wait_unlock_int(__lk_r, __msk_r); \
|
|
__pl_r = pl_xadd(__lk_r, __set_r) + __set_r; \
|
|
/* wait for all other readers to leave */ \
|
|
__m = 0; \
|
|
while (__builtin_expect(__pl_r & PLOCK32_RL_2PL, 0)) { \
|
|
unsigned char __loops; \
|
|
/* but rollback on other writers */ \
|
|
if (__builtin_expect(__pl_r & PLOCK32_WL_2PL, 0)) { \
|
|
pl_sub(__lk_r, __set_r); \
|
|
goto __retry; \
|
|
} \
|
|
__loops = __m + 1; \
|
|
__m = (__m << 1) + 1; \
|
|
do { \
|
|
pl_cpu_relax(); \
|
|
pl_cpu_relax(); \
|
|
} while (--__loops); \
|
|
__pl_r = pl_deref_int(__lk_r); \
|
|
} \
|
|
pl_barrier(); \
|
|
0; \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_take_j__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_take_j__(__FILE__,__LINE__); \
|
|
0; \
|
|
}) \
|
|
)
|
|
|
|
/* drop the join (J) lock entirely */
|
|
#define pl_drop_j(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
pl_barrier(); \
|
|
pl_sub(lock, PLOCK64_WL_1 | PLOCK64_RL_1); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
pl_barrier(); \
|
|
pl_sub(lock, PLOCK32_WL_1 | PLOCK32_RL_1); \
|
|
}) : ({ \
|
|
void __unsupported_argument_size_for_pl_drop_j__(char *,int); \
|
|
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
|
|
__unsupported_argument_size_for_pl_drop_j__(__FILE__,__LINE__); \
|
|
}) \
|
|
)
|
|
|
|
/*
|
|
* The part below is for Low Overhead R/W locks (LORW). These ones are not
|
|
* upgradable and not necessarily fair but they try to be fast when uncontended
|
|
* and to limit the cost and perturbation during contention. Writers always
|
|
* have precedence over readers to preserve latency as much as possible.
|
|
*
|
|
* The principle is to offer a fast no-contention path and a limited total
|
|
* number of writes for the contended path. Since R/W locks are expected to be
|
|
* used in situations where there is a benefit in separating reads from writes,
|
|
* it is expected that reads are common (typ >= 50%) and that there is often at
|
|
* least one reader (otherwise a spinlock wouldn't be a problem). As such, a
|
|
* reader will try to pass instantly, detect contention and immediately retract
|
|
* and wait in the queue in case there is contention. A writer will first also
|
|
* try to pass instantly, and if it fails due to pending readers, it will mark
|
|
* that it's waiting so that readers stop entering. This will leave the writer
|
|
* waiting as close as possible to the point of being granted access. New
|
|
* writers will also notice this previous contention and will wait outside.
|
|
* This means that a successful access for a reader or a writer requires a
|
|
* single CAS, and a contended attempt will require one failed CAS and one
|
|
* successful XADD for a reader, or an optional OR and a N+1 CAS for the
|
|
* writer.
|
|
*
|
|
* A counter of shared users indicates the number of active readers, while a
|
|
* (single-bit) counter of exclusive writers indicates whether the lock is
|
|
* currently held for writes. This distinction also permits to use a single
|
|
* function to release the lock if desired, since the exclusive bit indicates
|
|
* the state of the caller of unlock(). The WRQ bit is cleared during the
|
|
* unlock.
|
|
*
|
|
* Layout: (32/64 bit):
|
|
* 31 2 1 0
|
|
* +-----------+--------------+-----+-----+
|
|
* | | SHR | WRQ | EXC |
|
|
* +-----------+--------------+-----+-----+
|
|
*
|
|
* In order to minimize operations, the WRQ bit is held during EXC so that the
|
|
* write waiter that had to fight for EXC doesn't have to release WRQ during
|
|
* its operations, and will just drop it along with EXC upon unlock.
|
|
*
|
|
* This means the following costs:
|
|
* reader:
|
|
* success: 1 CAS
|
|
* failure: 1 CAS + 1 XADD
|
|
* unlock: 1 SUB
|
|
* writer:
|
|
* success: 1 RD + 1 CAS
|
|
* failure: 1 RD + 1 CAS + 0/1 OR + N CAS
|
|
* unlock: 1 AND
|
|
*/
|
|
|
|
#define PLOCK_LORW_EXC_BIT ((sizeof(long) == 8) ? 0 : 0)
|
|
#define PLOCK_LORW_EXC_SIZE ((sizeof(long) == 8) ? 1 : 1)
|
|
#define PLOCK_LORW_EXC_BASE (1UL << PLOCK_LORW_EXC_BIT)
|
|
#define PLOCK_LORW_EXC_MASK (((1UL << PLOCK_LORW_EXC_SIZE) - 1UL) << PLOCK_LORW_EXC_BIT)
|
|
|
|
#define PLOCK_LORW_WRQ_BIT ((sizeof(long) == 8) ? 1 : 1)
|
|
#define PLOCK_LORW_WRQ_SIZE ((sizeof(long) == 8) ? 1 : 1)
|
|
#define PLOCK_LORW_WRQ_BASE (1UL << PLOCK_LORW_WRQ_BIT)
|
|
#define PLOCK_LORW_WRQ_MASK (((1UL << PLOCK_LORW_WRQ_SIZE) - 1UL) << PLOCK_LORW_WRQ_BIT)
|
|
|
|
#define PLOCK_LORW_SHR_BIT ((sizeof(long) == 8) ? 2 : 2)
|
|
#define PLOCK_LORW_SHR_SIZE ((sizeof(long) == 8) ? 30 : 30)
|
|
#define PLOCK_LORW_SHR_BASE (1UL << PLOCK_LORW_SHR_BIT)
|
|
#define PLOCK_LORW_SHR_MASK (((1UL << PLOCK_LORW_SHR_SIZE) - 1UL) << PLOCK_LORW_SHR_BIT)
|
|
|
|
__attribute__((unused,always_inline,no_instrument_function))
|
|
static inline void pl_lorw_rdlock(unsigned long *lock)
|
|
{
|
|
unsigned long lk = 0;
|
|
|
|
/* First, assume we're alone and try to get the read lock (fast path).
|
|
* It often works because read locks are often used on low-contention
|
|
* structs.
|
|
*/
|
|
lk = pl_cmpxchg(lock, 0, PLOCK_LORW_SHR_BASE);
|
|
if (!lk)
|
|
return;
|
|
|
|
/* so we were not alone, make sure there's no writer waiting for the
|
|
* lock to be empty of visitors.
|
|
*/
|
|
if (lk & PLOCK_LORW_WRQ_MASK)
|
|
lk = pl_wait_unlock_long(lock, PLOCK_LORW_WRQ_MASK);
|
|
|
|
/* count us as visitor among others */
|
|
lk = pl_xadd(lock, PLOCK_LORW_SHR_BASE);
|
|
|
|
/* wait for end of exclusive access if any */
|
|
if (lk & PLOCK_LORW_EXC_MASK)
|
|
lk = pl_wait_unlock_long(lock, PLOCK_LORW_EXC_MASK);
|
|
}
|
|
|
|
|
|
__attribute__((unused,always_inline,no_instrument_function))
|
|
static inline void pl_lorw_wrlock(unsigned long *lock)
|
|
{
|
|
unsigned long lk = 0;
|
|
unsigned long old = 0;
|
|
|
|
/* first, make sure another writer is not already blocked waiting for
|
|
* readers to leave. Note that tests have shown that it can be even
|
|
* faster to avoid the first check and to unconditionally wait.
|
|
*/
|
|
lk = pl_deref_long(lock);
|
|
if (__builtin_expect(lk & PLOCK_LORW_WRQ_MASK, 1))
|
|
lk = pl_wait_unlock_long(lock, PLOCK_LORW_WRQ_MASK);
|
|
|
|
do {
|
|
/* let's check for the two sources of contention at once */
|
|
|
|
if (__builtin_expect(lk & (PLOCK_LORW_SHR_MASK | PLOCK_LORW_EXC_MASK), 1)) {
|
|
/* check if there are still readers coming. If so, close the door and
|
|
* wait for them to leave.
|
|
*/
|
|
if (lk & PLOCK_LORW_SHR_MASK) {
|
|
/* note below, an OR is significantly cheaper than BTS or XADD */
|
|
if (!(lk & PLOCK_LORW_WRQ_MASK))
|
|
pl_or(lock, PLOCK_LORW_WRQ_BASE);
|
|
lk = pl_wait_unlock_long(lock, PLOCK_LORW_SHR_MASK);
|
|
}
|
|
|
|
/* And also wait for a previous writer to finish. */
|
|
if (lk & PLOCK_LORW_EXC_MASK)
|
|
lk = pl_wait_unlock_long(lock, PLOCK_LORW_EXC_MASK);
|
|
}
|
|
|
|
/* A fresh new reader may appear right now if there were none
|
|
* above and we didn't close the door.
|
|
*/
|
|
old = lk & ~PLOCK_LORW_SHR_MASK & ~PLOCK_LORW_EXC_MASK;
|
|
lk = pl_cmpxchg(lock, old, old | PLOCK_LORW_EXC_BASE);
|
|
} while (lk != old);
|
|
|
|
/* done, not waiting anymore, the WRQ bit if any, will be dropped by the
|
|
* unlock
|
|
*/
|
|
}
|
|
|
|
|
|
__attribute__((unused,always_inline,no_instrument_function))
|
|
static inline void pl_lorw_rdunlock(unsigned long *lock)
|
|
{
|
|
pl_sub(lock, PLOCK_LORW_SHR_BASE);
|
|
}
|
|
|
|
__attribute__((unused,always_inline,no_instrument_function))
|
|
static inline void pl_lorw_wrunlock(unsigned long *lock)
|
|
{
|
|
pl_and(lock, ~(PLOCK_LORW_WRQ_MASK | PLOCK_LORW_EXC_MASK));
|
|
}
|
|
|
|
__attribute__((unused,always_inline,no_instrument_function))
|
|
static inline void pl_lorw_unlock(unsigned long *lock)
|
|
{
|
|
if (pl_deref_long(lock) & PLOCK_LORW_EXC_MASK)
|
|
pl_lorw_wrunlock(lock);
|
|
else
|
|
pl_lorw_rdunlock(lock);
|
|
}
|