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haproxy/include/import/plock.h

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/* plock - progressive locks
*
* Copyright (C) 2012-2017 Willy Tarreau <w@1wt.eu>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef PL_PLOCK_H
#define PL_PLOCK_H
#include "atomic-ops.h"
#ifdef _POSIX_PRIORITY_SCHEDULING
#include <sched.h>
#endif
/* 64 bit */
#define PLOCK64_RL_1 0x0000000000000004ULL
#define PLOCK64_RL_2PL 0x00000000FFFFFFF8ULL
#define PLOCK64_RL_ANY 0x00000000FFFFFFFCULL
#define PLOCK64_SL_1 0x0000000100000000ULL
#define PLOCK64_SL_ANY 0x0000000300000000ULL
#define PLOCK64_WL_1 0x0000000400000000ULL
#define PLOCK64_WL_2PL 0xFFFFFFF800000000ULL
#define PLOCK64_WL_ANY 0xFFFFFFFC00000000ULL
/* 32 bit */
#define PLOCK32_RL_1 0x00000004
#define PLOCK32_RL_2PL 0x0000FFF8
#define PLOCK32_RL_ANY 0x0000FFFC
#define PLOCK32_SL_1 0x00010000
#define PLOCK32_SL_ANY 0x00030000
#define PLOCK32_WL_1 0x00040000
#define PLOCK32_WL_2PL 0xFFF80000
#define PLOCK32_WL_ANY 0xFFFC0000
/* dereferences <*p> as unsigned long without causing aliasing issues */
#define pl_deref_long(p) ({ volatile unsigned long *__pl_l = (unsigned long *)(p); *__pl_l; })
/* dereferences <*p> as unsigned int without causing aliasing issues */
#define pl_deref_int(p) ({ volatile unsigned int *__pl_i = (unsigned int *)(p); *__pl_i; })
/* This function waits for <lock> to release all bits covered by <mask>, and
* enforces an exponential backoff using CPU pauses to limit the pollution to
* the other threads' caches. The progression follows (1.5^N)-1, limited to
* 16384 iterations, which is way sufficient even for very large numbers of
* threads. It's possible to disable exponential backoff (EBO) for debugging
* purposes by setting PLOCK_DISABLE_EBO, in which case the function will be
* replaced with a simpler macro. This may for example be useful to more
* easily track callers' CPU usage. The macro was not designed to be used
* outside of the functions defined here.
*/
#if defined(PLOCK_DISABLE_EBO)
#define pl_wait_unlock_long(lock, mask) \
({ \
unsigned long _r; \
do { \
pl_cpu_relax(); \
_r = pl_deref_long(lock); \
} while (_r & mask); \
_r; /* return value */ \
})
#else /* not PLOCK_DISABLE_EBO */
__attribute__((unused,always_inline,no_instrument_function)) inline
static unsigned long __pl_wait_unlock_long(const unsigned long *lock, const unsigned long mask)
{
unsigned long ret;
unsigned int m = 0;
do {
unsigned int loops = m;
#ifdef _POSIX_PRIORITY_SCHEDULING
if (loops >= 65536) {
sched_yield();
loops -= 32768;
}
#endif
for (; loops >= 60; loops --)
pl_cpu_relax();
for (; loops >= 1; loops--)
pl_barrier();
ret = pl_load(lock);
if (__builtin_expect(ret & mask, 0) == 0)
break;
/* the below produces an exponential growth with loops to lower
* values and still growing. This allows competing threads to
* wait different times once the threshold is reached.
*/
m = ((m + (m >> 1)) + 2) & 0x3ffff;
} while (1);
return ret;
}
# if defined(PLOCK_INLINE_EBO)
__attribute__((unused,always_inline,no_instrument_function)) inline
# else
__attribute__((unused,noinline,no_instrument_function))
# endif
static unsigned long pl_wait_unlock_long(const unsigned long *lock, const unsigned long mask)
{
return __pl_wait_unlock_long(lock, mask);
}
#endif /* PLOCK_DISABLE_EBO */
/* This function waits for <lock> to release all bits covered by <mask>, and
* enforces an exponential backoff using CPU pauses to limit the pollution to
* the other threads' caches. The progression follows (2^N)-1, limited to 255
* iterations, which is way sufficient even for very large numbers of threads.
* The function slightly benefits from size optimization under gcc, but Clang
* cannot do it, so it's not done here, as it doesn't make a big difference.
* It is possible to disable exponential backoff (EBO) for debugging purposes
* by setting PLOCK_DISABLE_EBO, in which case the function will be replaced
* with a simpler macro. This may for example be useful to more easily track
* callers' CPU usage. The macro was not designed to be used outside of the
* functions defined here.
*/
#if defined(PLOCK_DISABLE_EBO)
#define pl_wait_unlock_int(lock, mask) \
({ \
unsigned int _r; \
do { \
pl_cpu_relax(); \
_r = pl_deref_int(lock); \
} while (_r & mask); \
_r; /* return value */ \
})
#else
__attribute__((unused,always_inline,no_instrument_function)) inline
static unsigned int __pl_wait_unlock_int(const unsigned int *lock, const unsigned int mask)
{
unsigned int ret;
unsigned int m = 0;
do {
unsigned int loops = m;
#ifdef _POSIX_PRIORITY_SCHEDULING
if (loops >= 65536) {
sched_yield();
loops -= 32768;
}
#endif
for (; loops >= 200; loops -= 10)
pl_cpu_relax();
for (; loops >= 1; loops--)
pl_barrier();
ret = pl_deref_int(lock);
if (__builtin_expect(ret & mask, 0) == 0)
break;
/* the below produces an exponential growth with loops to lower
* values and still growing. This allows competing threads to
* wait different times once the threshold is reached.
*/
m = ((m + (m >> 1)) + 2) & 0x3ffff;
} while (1);
return ret;
}
# if defined(PLOCK_INLINE_EBO)
__attribute__((unused,always_inline,no_instrument_function)) inline
# else
__attribute__((unused,noinline,no_instrument_function))
# endif
static unsigned int pl_wait_unlock_int(const unsigned int *lock, const unsigned int mask)
{
return __pl_wait_unlock_int(lock, mask);
}
#endif /* PLOCK_DISABLE_EBO */
/* This function waits for <lock> to change from value <prev> and returns the
* new value. It enforces an exponential backoff using CPU pauses to limit the
* pollution to the other threads' caches. The progression follows (2^N)-1,
* limited to 255 iterations, which is way sufficient even for very large
* numbers of threads. It is designed to be called after a first test which
* retrieves the previous value, so it starts by waiting. The function slightly
* benefits from size optimization under gcc, but Clang cannot do it, so it's
* not done here, as it doesn't make a big difference.
*/
__attribute__((unused,noinline,no_instrument_function))
static unsigned long pl_wait_new_long(const unsigned long *lock, const unsigned long prev)
{
unsigned char m = 0;
unsigned long curr;
do {
unsigned char loops = m + 1;
m = (m << 1) + 1;
do {
pl_cpu_relax();
} while (__builtin_expect(--loops, 0));
curr = pl_deref_long(lock);
} while (__builtin_expect(curr == prev, 0));
return curr;
}
/* This function waits for <lock> to change from value <prev> and returns the
* new value. It enforces an exponential backoff using CPU pauses to limit the
* pollution to the other threads' caches. The progression follows (2^N)-1,
* limited to 255 iterations, which is way sufficient even for very large
* numbers of threads. It is designed to be called after a first test which
* retrieves the previous value, so it starts by waiting. The function slightly
* benefits from size optimization under gcc, but Clang cannot do it, so it's
* not done here, as it doesn't make a big difference.
*/
__attribute__((unused,noinline,no_instrument_function))
static unsigned int pl_wait_new_int(const unsigned int *lock, const unsigned int prev)
{
unsigned char m = 0;
unsigned int curr;
do {
unsigned char loops = m + 1;
m = (m << 1) + 1;
do {
pl_cpu_relax();
} while (__builtin_expect(--loops, 0));
curr = pl_deref_int(lock);
} while (__builtin_expect(curr == prev, 0));
return curr;
}
/* request shared read access (R), return non-zero on success, otherwise 0 */
#define pl_try_r(lock) ( \
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
register unsigned long __pl_r = pl_deref_long(lock) & PLOCK64_WL_ANY; \
pl_barrier(); \
if (!__builtin_expect(__pl_r, 0)) { \
__pl_r = pl_ldadd_acq((lock), PLOCK64_RL_1) & PLOCK64_WL_ANY; \
if (__builtin_expect(__pl_r, 0)) \
pl_sub_noret((lock), PLOCK64_RL_1); \
} \
!__pl_r; /* return value */ \
}) : (sizeof(*(lock)) == 4) ? ({ \
register unsigned int __pl_r = pl_deref_int(lock) & PLOCK32_WL_ANY; \
pl_barrier(); \
if (!__builtin_expect(__pl_r, 0)) { \
__pl_r = pl_ldadd_acq((lock), PLOCK32_RL_1) & PLOCK32_WL_ANY; \
if (__builtin_expect(__pl_r, 0)) \
pl_sub_noret((lock), PLOCK32_RL_1); \
} \
!__pl_r; /* return value */ \
}) : ({ \
void __unsupported_argument_size_for_pl_try_r__(char *,int); \
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
__unsupported_argument_size_for_pl_try_r__(__FILE__,__LINE__); \
0; \
}) \
)
/* request shared read access (R) and wait for it. In order not to disturb a W
* lock waiting for all readers to leave, we first check if a W lock is held
* before trying to claim the R lock.
*/
#define pl_take_r(lock) \
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
register unsigned long *__lk_r = (unsigned long *)(lock); \
register unsigned long __set_r = PLOCK64_RL_1; \
register unsigned long __msk_r = PLOCK64_WL_ANY; \
register unsigned long __old_r = pl_cmpxchg(__lk_r, 0, __set_r); \
if (__old_r) { \
while (1) { \
if (__old_r & __msk_r) \
pl_wait_unlock_long(__lk_r, __msk_r); \
if (!(pl_ldadd_acq(__lk_r, __set_r) & __msk_r)) \
break; \
__old_r = pl_sub_lax(__lk_r, __set_r); \
} \
} \
pl_barrier(); \
0; \
}) : (sizeof(*(lock)) == 4) ? ({ \
register unsigned int *__lk_r = (unsigned int *)(lock); \
register unsigned int __set_r = PLOCK32_RL_1; \
register unsigned int __msk_r = PLOCK32_WL_ANY; \
register unsigned int __old_r = pl_cmpxchg(__lk_r, 0, __set_r); \
if (__old_r) { \
while (1) { \
if (__old_r & __msk_r) \
pl_wait_unlock_int(__lk_r, __msk_r); \
if (!(pl_ldadd_acq(__lk_r, __set_r) & __msk_r)) \
break; \
__old_r = pl_sub_lax(__lk_r, __set_r); \
} \
} \
pl_barrier(); \
0; \
}) : ({ \
void __unsupported_argument_size_for_pl_take_r__(char *,int); \
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
__unsupported_argument_size_for_pl_take_r__(__FILE__,__LINE__); \
0; \
})
/* release the read access (R) lock */
#define pl_drop_r(lock) ( \
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
pl_barrier(); \
pl_sub_noret_rel(lock, PLOCK64_RL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub_noret_rel(lock, PLOCK32_RL_1); \
}) : ({ \
void __unsupported_argument_size_for_pl_drop_r__(char *,int); \
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
__unsupported_argument_size_for_pl_drop_r__(__FILE__,__LINE__); \
}) \
)
/* request a seek access (S), return non-zero on success, otherwise 0 */
#define pl_try_s(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_ldadd_acq((lock), PLOCK64_SL_1 | PLOCK64_RL_1) & \
(PLOCK64_WL_ANY | PLOCK64_SL_ANY); \
if (__builtin_expect(__pl_r, 0)) \
pl_sub_noret_lax((lock), 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_ldadd_acq((lock), PLOCK32_SL_1 | PLOCK32_RL_1) & \
(PLOCK32_WL_ANY | PLOCK32_SL_ANY); \
if (__builtin_expect(__pl_r, 0)) \
pl_sub_noret_lax((lock), PLOCK32_SL_1 | PLOCK32_RL_1); \
} \
!__pl_r; /* return value */ \
}) : ({ \
void __unsupported_argument_size_for_pl_try_s__(char *,int); \
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
__unsupported_argument_size_for_pl_try_s__(__FILE__,__LINE__); \
0; \
}) \
)
/* request a seek access (S) and wait for it. The lock is immediately claimed,
* and only upon failure an exponential backoff is used. S locks rarely compete
* with W locks so S will generally not disturb W. As the S lock may be used as
* a spinlock, it's important to grab it as fast as possible.
*/
#define pl_take_s(lock) \
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
register unsigned long *__lk_r = (unsigned long *)(lock); \
register unsigned long __set_r = PLOCK64_SL_1 | PLOCK64_RL_1; \
register unsigned long __msk_r = PLOCK64_WL_ANY | PLOCK64_SL_ANY; \
while (1) { \
if (!__builtin_expect(pl_ldadd_acq(__lk_r, __set_r) & __msk_r, 0)) \
break; \
pl_sub_noret_lax(__lk_r, __set_r); \
pl_wait_unlock_long(__lk_r, __msk_r); \
} \
pl_barrier(); \
0; \
}) : (sizeof(*(lock)) == 4) ? ({ \
register unsigned int *__lk_r = (unsigned int *)(lock); \
register unsigned int __set_r = PLOCK32_SL_1 | PLOCK32_RL_1; \
register unsigned int __msk_r = PLOCK32_WL_ANY | PLOCK32_SL_ANY; \
while (1) { \
if (!__builtin_expect(pl_ldadd_acq(__lk_r, __set_r) & __msk_r, 0)) \
break; \
pl_sub_noret_lax(__lk_r, __set_r); \
pl_wait_unlock_int(__lk_r, __msk_r); \
} \
pl_barrier(); \
0; \
}) : ({ \
void __unsupported_argument_size_for_pl_take_s__(char *,int); \
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
__unsupported_argument_size_for_pl_take_s__(__FILE__,__LINE__); \
0; \
})
/* release the seek access (S) lock */
#define pl_drop_s(lock) ( \
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
pl_barrier(); \
pl_sub_noret_rel(lock, PLOCK64_SL_1 + PLOCK64_RL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub_noret_rel(lock, PLOCK32_SL_1 + PLOCK32_RL_1); \
}) : ({ \
void __unsupported_argument_size_for_pl_drop_s__(char *,int); \
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
__unsupported_argument_size_for_pl_drop_s__(__FILE__,__LINE__); \
}) \
)
/* drop the S lock and go back to the R lock */
#define pl_stor(lock) ( \
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
pl_barrier(); \
pl_sub_noret(lock, PLOCK64_SL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub_noret(lock, PLOCK32_SL_1); \
}) : ({ \
void __unsupported_argument_size_for_pl_stor__(char *,int); \
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
__unsupported_argument_size_for_pl_stor__(__FILE__,__LINE__); \
}) \
)
/* take the W lock under the S lock */
#define pl_stow(lock) ( \
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
register unsigned long __pl_r = pl_ldadd((lock), PLOCK64_WL_1); \
if (__pl_r & (PLOCK64_RL_ANY & ~PLOCK64_RL_1)) \
__pl_r = pl_wait_unlock_long((const unsigned long*)lock, (PLOCK64_RL_ANY & ~PLOCK64_RL_1)); \
pl_barrier(); \
}) : (sizeof(*(lock)) == 4) ? ({ \
register unsigned int __pl_r = pl_ldadd((lock), PLOCK32_WL_1); \
if (__pl_r & (PLOCK32_RL_ANY & ~PLOCK32_RL_1)) \
__pl_r = pl_wait_unlock_int((const unsigned int*)lock, (PLOCK32_RL_ANY & ~PLOCK32_RL_1)); \
pl_barrier(); \
}) : ({ \
void __unsupported_argument_size_for_pl_stow__(char *,int); \
if (sizeof(*(lock)) != 4 && (sizeof(long) != 8 || sizeof(*(lock)) != 8)) \
__unsupported_argument_size_for_pl_stow__(__FILE__,__LINE__); \
}) \
)
/* drop the W lock and go back to the S lock */
#define pl_wtos(lock) ( \
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
pl_barrier(); \
pl_sub_noret(lock, PLOCK64_WL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub_noret(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_noret(lock, PLOCK64_WL_1 | PLOCK64_SL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub_noret(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_ldadd_acq((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_noret_lax((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_ldadd_acq((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_noret_lax((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_ldadd_acq(__lk_r, __set_r); \
if (!__builtin_expect(__pl_r & __msk_r, 0)) \
break; \
pl_sub_noret_lax(__lk_r, __set_r); \
__pl_r = pl_wait_unlock_long(__lk_r, __msk_r); \
} \
/* wait for all other readers to leave */ \
if (__builtin_expect(__pl_r & PLOCK64_RL_ANY, 0)) \
__pl_r = pl_wait_unlock_long(__lk_r, (PLOCK64_RL_ANY & ~PLOCK64_RL_1)) - __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_ldadd_acq(__lk_r, __set_r); \
if (!__builtin_expect(__pl_r & __msk_r, 0)) \
break; \
pl_sub_noret_lax(__lk_r, __set_r); \
__pl_r = pl_wait_unlock_int(__lk_r, __msk_r); \
} \
/* wait for all other readers to leave */ \
if (__builtin_expect(__pl_r & PLOCK32_RL_ANY, 0)) \
__pl_r = pl_wait_unlock_int(__lk_r, (PLOCK32_RL_ANY & ~PLOCK32_RL_1)) - __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_noret_rel(lock, PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub_noret_rel(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_r = pl_ldadd_acq((lock), PLOCK64_SL_1) & (PLOCK64_WL_ANY | PLOCK64_SL_ANY);\
if (__builtin_expect(__pl_r, 0)) \
pl_sub_noret_lax((lock), PLOCK64_SL_1); \
!__pl_r; /* return value */ \
}) : (sizeof(*(lock)) == 4) ? ({ \
register unsigned int __pl_r; \
__pl_r = pl_ldadd_acq((lock), PLOCK32_SL_1) & (PLOCK32_WL_ANY | PLOCK32_SL_ANY);\
if (__builtin_expect(__pl_r, 0)) \
pl_sub_noret_lax((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_ldadd_acq(__lk_r, __set_r); \
if (__builtin_expect(__pl_r & __msk_r, 0)) { \
if (pl_ldadd_lax(__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_ldadd_acq(__lk_r, __set_r); \
if (__builtin_expect(__pl_r & __msk_r, 0)) { \
if (pl_ldadd_lax(__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_ldadd_acq((lock), PLOCK64_WL_1); \
while (1) { \
if (__builtin_expect(__pl_r & PLOCK64_SL_ANY, 0)) { \
pl_sub_noret_lax((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_ldadd_acq((lock), PLOCK32_WL_1); \
while (1) { \
if (__builtin_expect(__pl_r & PLOCK32_SL_ANY, 0)) { \
pl_sub_noret_lax((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_ldadd_acq(__lk_r, __set_r); \
while (__builtin_expect(__pl_r & PLOCK64_RL_ANY, 0)) { \
if (__builtin_expect(__pl_r & __msk_r, 0)) { \
pl_sub_noret_lax(__lk_r, __set_r); \
pl_wait_unlock_long(__lk_r, __msk_r); \
__pl_r = pl_ldadd_acq(__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_ldadd_acq(__lk_r, __set_r); \
while (__builtin_expect(__pl_r & PLOCK32_RL_ANY, 0)) { \
if (__builtin_expect(__pl_r & __msk_r, 0)) { \
pl_sub_noret_lax(__lk_r, __set_r); \
pl_wait_unlock_int(__lk_r, __msk_r); \
__pl_r = pl_ldadd_acq(__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_noret_rel(lock, PLOCK64_WL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub_noret_rel(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_ldadd(__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_ldadd(__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_ldadd_acq((lock), PLOCK64_WL_1 - PLOCK64_RL_1); \
while (1) { \
if (__builtin_expect(__pl_r & PLOCK64_SL_ANY, 0)) { \
pl_sub_noret_lax((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_ldadd_acq((lock), PLOCK32_WL_1 - PLOCK32_RL_1); \
while (1) { \
if (__builtin_expect(__pl_r & PLOCK32_SL_ANY, 0)) { \
pl_sub_noret_lax((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_ldadd_acq(__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_ldadd_acq(__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_noret(__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_noret(__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_ldadd_acq(__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_noret(__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_ldadd_acq(__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_noret(__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_ldadd(__lk_r, __set_r) + __set_r; \
if (!(__pl_r & PLOCK64_RL_ANY)) \
pl_and_noret(__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_ldadd(__lk_r, __set_r) + __set_r; \
if (!(__pl_r & PLOCK32_RL_ANY)) \
pl_and_noret(__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_ldadd(__lk_r, -PLOCK64_RL_1) - PLOCK64_RL_1;\
while (__pl_r & PLOCK64_SL_ANY) { \
if (!(__pl_r & PLOCK64_RL_ANY)) { \
pl_and_noret(__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_ldadd(__lk_r, -PLOCK32_RL_1) - PLOCK32_RL_1; \
while (__pl_r & PLOCK32_SL_ANY) { \
if (!(__pl_r & PLOCK32_RL_ANY)) { \
pl_and_noret(__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_noret(lock, PLOCK64_RL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_add_noret(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_ldadd_acq(__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_noret_lax(__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_ldadd_acq(__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_noret_lax(__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_ldadd_acq(__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_noret_lax(__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_ldadd_acq(__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_noret_lax(__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_noret_rel(lock, PLOCK64_WL_1 | PLOCK64_RL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub_noret_rel(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)
#if defined(PLOCK_LORW_INLINE_WAIT) && !defined(PLOCK_DISABLE_EBO)
lk = __pl_wait_unlock_long(lock, PLOCK_LORW_WRQ_MASK);
#else
lk = pl_wait_unlock_long(lock, PLOCK_LORW_WRQ_MASK);
#endif
/* count us as visitor among others */
lk = pl_ldadd_acq(lock, PLOCK_LORW_SHR_BASE);
/* wait for end of exclusive access if any */
if (lk & PLOCK_LORW_EXC_MASK)
#if defined(PLOCK_LORW_INLINE_WAIT) && !defined(PLOCK_DISABLE_EBO)
lk = __pl_wait_unlock_long(lock, PLOCK_LORW_EXC_MASK);
#else
lk = pl_wait_unlock_long(lock, PLOCK_LORW_EXC_MASK);
#endif
}
__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))
#if defined(PLOCK_LORW_INLINE_WAIT) && !defined(PLOCK_DISABLE_EBO)
lk = __pl_wait_unlock_long(lock, PLOCK_LORW_WRQ_MASK);
#else
lk = pl_wait_unlock_long(lock, PLOCK_LORW_WRQ_MASK);
#endif
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_noret(lock, PLOCK_LORW_WRQ_BASE);
#if defined(PLOCK_LORW_INLINE_WAIT) && !defined(PLOCK_DISABLE_EBO)
lk = __pl_wait_unlock_long(lock, PLOCK_LORW_SHR_MASK);
#else
lk = pl_wait_unlock_long(lock, PLOCK_LORW_SHR_MASK);
#endif
}
/* And also wait for a previous writer to finish. */
if (lk & PLOCK_LORW_EXC_MASK)
#if defined(PLOCK_LORW_INLINE_WAIT) && !defined(PLOCK_DISABLE_EBO)
lk = __pl_wait_unlock_long(lock, PLOCK_LORW_EXC_MASK);
#else
lk = pl_wait_unlock_long(lock, PLOCK_LORW_EXC_MASK);
#endif
}
/* 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_noret_rel(lock, PLOCK_LORW_SHR_BASE);
}
__attribute__((unused,always_inline,no_instrument_function))
static inline void pl_lorw_wrunlock(unsigned long *lock)
{
pl_and_noret_rel(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);
}
#endif /* PL_PLOCK_H */
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