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plock.h
executable file
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plock.h
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/* plock - progressive locks
*
* Copyright (C) 2012-2017 Willy Tarreau <[email protected]>
*
* 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.
*/
#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
__attribute__((unused,noinline,no_instrument_function))
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 >= 200; loops -= 10)
pl_cpu_relax();
for (; loops >= 1; loops--)
pl_barrier();
ret = pl_deref_long(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;
}
#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,noinline,no_instrument_function))
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;
}
#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_xadd((lock), PLOCK64_RL_1) & PLOCK64_WL_ANY; \
if (__builtin_expect(__pl_r, 0)) \
pl_sub((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_xadd((lock), PLOCK32_RL_1) & PLOCK32_WL_ANY; \
if (__builtin_expect(__pl_r, 0)) \
pl_sub((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; \
while (1) { \
if (__builtin_expect(pl_deref_long(__lk_r) & __msk_r, 0)) \
pl_wait_unlock_long(__lk_r, __msk_r); \
if (!__builtin_expect(pl_xadd(__lk_r, __set_r) & __msk_r, 0)) \
break; \
pl_sub(__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; \
while (1) { \
if (__builtin_expect(pl_deref_int(__lk_r) & __msk_r, 0)) \
pl_wait_unlock_int(__lk_r, __msk_r); \
if (!__builtin_expect(pl_xadd(__lk_r, __set_r) & __msk_r, 0)) \
break; \
pl_sub(__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(lock, PLOCK64_RL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub(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_xadd((lock), PLOCK64_SL_1 | PLOCK64_RL_1) & \
(PLOCK64_WL_ANY | PLOCK64_SL_ANY); \
if (__builtin_expect(__pl_r, 0)) \
pl_sub((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_xadd((lock), PLOCK32_SL_1 | PLOCK32_RL_1) & \
(PLOCK32_WL_ANY | PLOCK32_SL_ANY); \
if (__builtin_expect(__pl_r, 0)) \
pl_sub((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_xadd(__lk_r, __set_r) & __msk_r, 0)) \
break; \
pl_sub(__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_xadd(__lk_r, __set_r) & __msk_r, 0)) \
break; \
pl_sub(__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(lock, PLOCK64_SL_1 + PLOCK64_RL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub(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(lock, PLOCK64_SL_1); \
}) : (sizeof(*(lock)) == 4) ? ({ \
pl_barrier(); \
pl_sub(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_xadd((lock), PLOCK64_WL_1); \
while ((__pl_r & PLOCK64_RL_ANY) != PLOCK64_RL_1) \
__pl_r = pl_deref_long(lock); \
pl_barrier(); \
}) : (sizeof(*(lock)) == 4) ? ({ \
register unsigned int __pl_r = pl_xadd((lock), PLOCK32_WL_1); \
while ((__pl_r & PLOCK32_RL_ANY) != PLOCK32_RL_1) \
__pl_r = pl_deref_int(lock); \
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(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(); \