mirror of
http://git.haproxy.org/git/haproxy.git/
synced 2024-12-12 22:44:32 +00:00
2532bd2f81
[ plock commit 4c53fd3a0b2b1892817cebd0db012a52f4087850 ]
Pieter Baauw reported a build issue affecting haproxy after plock was
included. It happens that expressions of the form :
if ((const) ? (expr1) : (expr2))
do_something()
always produce code for both expr1 and expr2 on Clang when building
without optimization. The resulting asm code is even funny, basically
doing :
mov reg, 1
cmp reg, 1
...
This causes our sizeof() tests to fail to build because we purposely
dereference a fake function that reports the location and nature of the
inconsistency, but this fake function appears in the object code despite
all conditions being there to avoid it.
However the compiler is still smart enough to optimize away code doing
if (const)
do_something()
So we simply repeat the condition before do_something(), and the dummy
function is not referenced anymore unless really required.
442 lines
29 KiB
C
442 lines
29 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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/* 64 bit */
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#define PLOCK64_RL_1 0x0000000000000004ULL
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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_ANY 0xFFFFFFFC00000000ULL
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/* 32 bit */
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#define PLOCK32_RL_1 0x00000004
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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_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 = (void *)(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 = (void *)(p); *__pl_i; })
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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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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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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 */
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#define pl_take_r(lock) \
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do { \
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while (__builtin_expect(pl_try_r(lock), 1) == 0) \
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pl_cpu_relax(); \
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} while (0)
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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_sub(lock, PLOCK64_RL_1); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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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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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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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 */
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#define pl_take_s(lock) \
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do { \
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while (__builtin_expect(pl_try_s(lock), 0) == 0) \
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pl_cpu_relax(); \
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} while (0)
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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_sub(lock, PLOCK64_SL_1 + PLOCK64_RL_1); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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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_sub(lock, PLOCK64_SL_1); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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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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unsigned long __pl_r = pl_xadd((lock), PLOCK64_WL_1); \
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pl_barrier(); \
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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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}) : (sizeof(*(lock)) == 4) ? ({ \
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unsigned int __pl_r = pl_xadd((lock), PLOCK32_WL_1); \
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pl_barrier(); \
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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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}) : ({ \
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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_sub(lock, PLOCK64_WL_1); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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pl_sub(lock, PLOCK32_WL_1); \
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}) : ({ \
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void __unsupported_argument_size_for_pl_wtos__(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_wtos__(__FILE__,__LINE__); \
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}) \
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)
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/* drop the W lock and go back to the R lock */
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#define pl_wtor(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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pl_sub(lock, PLOCK64_WL_1 | PLOCK64_SL_1); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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pl_sub(lock, PLOCK32_WL_1 | PLOCK32_SL_1); \
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}) : ({ \
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void __unsupported_argument_size_for_pl_wtor__(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_wtor__(__FILE__,__LINE__); \
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}) \
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)
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/* request a write access (W), return non-zero on success, otherwise 0.
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*
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* Below there is something important : by taking both W and S, we will cause
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* an overflow of W at 4/5 of the maximum value that can be stored into W due
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* to the fact that S is 2 bits, so we're effectively adding 5 to the word
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* composed by W:S. But for all words multiple of 4 bits, the maximum value is
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* multiple of 15 thus of 5. So the largest value we can store with all bits
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* set to one will be met by adding 5, and then adding 5 again will place value
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* 1 in W and value 0 in S, so we never leave W with 0. Also, even upon such an
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* overflow, there's no risk to confuse it with an atomic lock because R is not
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* null since it will not have overflown. For 32-bit locks, this situation
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* happens when exactly 13108 threads try to grab the lock at once, W=1, S=0
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* and R=13108. For 64-bit locks, it happens at 858993460 concurrent writers
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* where W=1, S=0 and R=858993460.
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*/
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#define pl_try_w(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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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_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
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if (__builtin_expect(__pl_r & (PLOCK64_WL_ANY | PLOCK64_SL_ANY), 0)) { \
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/* a writer, seeker or atomic is present, let's leave */ \
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pl_sub((lock), PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
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__pl_r &= (PLOCK64_WL_ANY | PLOCK64_SL_ANY); /* return value */\
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} else { \
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/* wait for all other readers to leave */ \
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while (__pl_r) \
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__pl_r = pl_deref_long(lock) - \
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(PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
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__pl_r = 0; \
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} \
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} \
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!__pl_r; /* return value */ \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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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_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
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if (__builtin_expect(__pl_r & (PLOCK32_WL_ANY | PLOCK32_SL_ANY), 0)) { \
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/* a writer, seeker or atomic is present, let's leave */ \
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pl_sub((lock), PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
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__pl_r &= (PLOCK32_WL_ANY | PLOCK32_SL_ANY); /* return value */\
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} else { \
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/* wait for all other readers to leave */ \
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while (__pl_r) \
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__pl_r = pl_deref_int(lock) - \
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(PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
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__pl_r = 0; \
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} \
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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_w__(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_w__(__FILE__,__LINE__); \
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0; \
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}) \
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)
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/* request a seek access (W) and wait for it */
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#define pl_take_w(lock) \
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do { \
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while (__builtin_expect(pl_try_w(lock), 0) == 0) \
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pl_cpu_relax(); \
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} while (0)
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/* drop the write (W) lock entirely */
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#define pl_drop_w(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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pl_sub(lock, PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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pl_sub(lock, PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
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}) : ({ \
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void __unsupported_argument_size_for_pl_drop_w__(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_w__(__FILE__,__LINE__); \
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}) \
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)
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/* Try to upgrade from R to S, return non-zero on success, otherwise 0.
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* This lock will fail if S or W are already held. In case of failure to grab
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* the lock, it MUST NOT be retried without first dropping R, or it may never
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* complete due to S waiting for R to leave before upgrading to W.
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*/
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#define pl_try_rtos(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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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) & \
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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); \
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} \
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!__pl_r; /* return value */ \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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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) & \
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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); \
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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_rtos__(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_rtos__(__FILE__,__LINE__); \
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0; \
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}) \
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)
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/* request atomic write access (A), return non-zero on success, otherwise 0.
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* It's a bit tricky as we only use the W bits for this and want to distinguish
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* between other atomic users and regular lock users. We have to give up if an
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* S lock appears. It's possible that such a lock stays hidden in the W bits
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* after an overflow, but in this case R is still held, ensuring we stay in the
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* loop until we discover the conflict. The lock only return successfully if all
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* readers are gone (or converted to A).
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*/
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#define pl_try_a(lock) ( \
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(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
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unsigned long __pl_r = pl_deref_long(lock) & PLOCK64_SL_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_WL_1); \
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while (1) { \
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if (__builtin_expect(__pl_r & PLOCK64_SL_ANY, 0)) { \
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pl_sub((lock), PLOCK64_WL_1); \
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break; /* return !__pl_r */ \
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} \
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__pl_r &= PLOCK64_RL_ANY; \
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if (!__builtin_expect(__pl_r, 0)) \
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break; /* return !__pl_r */ \
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__pl_r = pl_deref_long(lock); \
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} \
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} \
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!__pl_r; /* return value */ \
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}) : (sizeof(*(lock)) == 4) ? ({ \
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unsigned int __pl_r = pl_deref_int(lock) & PLOCK32_SL_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_WL_1); \
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while (1) { \
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if (__builtin_expect(__pl_r & PLOCK32_SL_ANY, 0)) { \
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pl_sub((lock), PLOCK32_WL_1); \
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break; /* return !__pl_r */ \
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} \
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__pl_r &= PLOCK32_RL_ANY; \
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if (!__builtin_expect(__pl_r, 0)) \
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break; /* return !__pl_r */ \
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__pl_r = pl_deref_int(lock); \
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} \
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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_a__(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_a__(__FILE__,__LINE__); \
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0; \
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}) \
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)
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|
|
|
/* request atomic write access (A) and wait for it */
|
|
#define pl_take_a(lock) \
|
|
do { \
|
|
while (__builtin_expect(pl_try_a(lock), 1) == 0) \
|
|
pl_cpu_relax(); \
|
|
} while (0)
|
|
|
|
/* release atomic write access (A) lock */
|
|
#define pl_drop_a(lock) ( \
|
|
(sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
|
|
pl_sub(lock, PLOCK64_WL_1); \
|
|
}) : (sizeof(*(lock)) == 4) ? ({ \
|
|
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__); \
|
|
}) \
|
|
)
|
|
|
|
/* 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) ? ({ \
|
|
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) ? ({ \
|
|
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; \
|
|
}) \
|
|
)
|