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Diffstat (limited to 'include/import/plock.h')
| -rw-r--r-- | include/import/plock.h | 1422 |
1 files changed, 1422 insertions, 0 deletions
diff --git a/include/import/plock.h b/include/import/plock.h new file mode 100644 index 0000000..fc001e2 --- /dev/null +++ b/include/import/plock.h @@ -0,0 +1,1422 @@ +/* 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 */ |