diff options
Diffstat (limited to 'absl/synchronization/mutex.cc')
| -rw-r--r-- | absl/synchronization/mutex.cc | 107 |
1 files changed, 69 insertions, 38 deletions
diff --git a/absl/synchronization/mutex.cc b/absl/synchronization/mutex.cc index 6b2eb3314796..37ffff3da872 100644 --- a/absl/synchronization/mutex.cc +++ b/absl/synchronization/mutex.cc @@ -118,6 +118,10 @@ ABSL_CONST_INIT absl::base_internal::AtomicHook< } // namespace +static inline bool EvalConditionAnnotated(const Condition *cond, Mutex *mu, + bool locking, bool trylock, + bool read_lock); + void RegisterMutexProfiler(void (*fn)(int64_t wait_timestamp)) { submit_profile_data.Store(fn); } @@ -233,15 +237,14 @@ enum { // Mutex and CondVar events passed as "ev" to PostSynchEvent SYNCH_EV_SIGNALALL, }; -enum { // Event flags - SYNCH_F_R = 0x01, // reader event - SYNCH_F_LCK = 0x02, // PostSynchEvent called with mutex held - SYNCH_F_ACQ = 0x04, // event is an acquire +enum { // Event flags + SYNCH_F_R = 0x01, // reader event + SYNCH_F_LCK = 0x02, // PostSynchEvent called with mutex held + SYNCH_F_TRY = 0x04, // TryLock or ReaderTryLock + SYNCH_F_UNLOCK = 0x08, // Unlock or ReaderUnlock SYNCH_F_LCK_W = SYNCH_F_LCK, SYNCH_F_LCK_R = SYNCH_F_LCK | SYNCH_F_R, - SYNCH_F_ACQ_W = SYNCH_F_ACQ, - SYNCH_F_ACQ_R = SYNCH_F_ACQ | SYNCH_F_R, }; } // anonymous namespace @@ -250,20 +253,20 @@ static const struct { int flags; const char *msg; } event_properties[] = { - { SYNCH_F_LCK_W|SYNCH_F_ACQ_W, "TryLock succeeded " }, - { 0, "TryLock failed " }, - { SYNCH_F_LCK_R|SYNCH_F_ACQ_R, "ReaderTryLock succeeded " }, - { 0, "ReaderTryLock failed " }, - { SYNCH_F_ACQ_W, "Lock blocking " }, - { SYNCH_F_LCK_W, "Lock returning " }, - { SYNCH_F_ACQ_R, "ReaderLock blocking " }, - { SYNCH_F_LCK_R, "ReaderLock returning " }, - { SYNCH_F_LCK_W, "Unlock " }, - { SYNCH_F_LCK_R, "ReaderUnlock " }, - { 0, "Wait on " }, - { 0, "Wait unblocked " }, - { 0, "Signal on " }, - { 0, "SignalAll on " }, + {SYNCH_F_LCK_W | SYNCH_F_TRY, "TryLock succeeded "}, + {0, "TryLock failed "}, + {SYNCH_F_LCK_R | SYNCH_F_TRY, "ReaderTryLock succeeded "}, + {0, "ReaderTryLock failed "}, + {0, "Lock blocking "}, + {SYNCH_F_LCK_W, "Lock returning "}, + {0, "ReaderLock blocking "}, + {SYNCH_F_LCK_R, "ReaderLock returning "}, + {SYNCH_F_LCK_W | SYNCH_F_UNLOCK, "Unlock "}, + {SYNCH_F_LCK_R | SYNCH_F_UNLOCK, "ReaderUnlock "}, + {0, "Wait on "}, + {0, "Wait unblocked "}, + {0, "Signal on "}, + {0, "SignalAll on "}, }; static absl::base_internal::SpinLock synch_event_mu( @@ -415,9 +418,26 @@ static void PostSynchEvent(void *obj, int ev) { ABSL_RAW_LOG(INFO, "%s%p %s %s", event_properties[ev].msg, obj, (e == nullptr ? "" : e->name), buffer); } - if ((event_properties[ev].flags & SYNCH_F_LCK) != 0 && e != nullptr && - e->invariant != nullptr) { - (*e->invariant)(e->arg); + const int flags = event_properties[ev].flags; + if ((flags & SYNCH_F_LCK) != 0 && e != nullptr && e->invariant != nullptr) { + // Calling the invariant as is causes problems under ThreadSanitizer. + // We are currently inside of Mutex Lock/Unlock and are ignoring all + // memory accesses and synchronization. If the invariant transitively + // synchronizes something else and we ignore the synchronization, we will + // get false positive race reports later. + // Reuse EvalConditionAnnotated to properly call into user code. + struct local { + static bool pred(SynchEvent *ev) { + (*ev->invariant)(ev->arg); + return false; + } + }; + Condition cond(&local::pred, e); + Mutex *mu = static_cast<Mutex *>(obj); + const bool locking = (flags & SYNCH_F_UNLOCK) == 0; + const bool trylock = (flags & SYNCH_F_TRY) != 0; + const bool read_lock = (flags & SYNCH_F_R) != 0; + EvalConditionAnnotated(&cond, mu, locking, trylock, read_lock); } UnrefSynchEvent(e); } @@ -1553,7 +1573,7 @@ bool Mutex::AwaitCommon(const Condition &cond, KernelTimeout t) { ABSL_TSAN_MUTEX_PRE_LOCK(this, TsanFlags(how)); this->LockSlowLoop(&waitp, flags); bool res = waitp.cond != nullptr || // => cond known true from LockSlowLoop - cond.Eval(); + EvalConditionAnnotated(&cond, this, true, false, how == kShared); ABSL_TSAN_MUTEX_POST_LOCK(this, TsanFlags(how), 0); return res; } @@ -1731,12 +1751,17 @@ void Mutex::LockSlow(MuHow how, const Condition *cond, int flags) { // Compute cond->Eval() and tell race detectors that we do it under mutex mu. static inline bool EvalConditionAnnotated(const Condition *cond, Mutex *mu, - bool locking, Mutex::MuHow how) { + bool locking, bool trylock, + bool read_lock) { // Delicate annotation dance. // We are currently inside of read/write lock/unlock operation. // All memory accesses are ignored inside of mutex operations + for unlock // operation tsan considers that we've already released the mutex. bool res = false; +#ifdef THREAD_SANITIZER + const int flags = read_lock ? __tsan_mutex_read_lock : 0; + const int tryflags = flags | (trylock ? __tsan_mutex_try_lock : 0); +#endif if (locking) { // For lock we pretend that we have finished the operation, // evaluate the predicate, then unlock the mutex and start locking it again @@ -1744,24 +1769,26 @@ static inline bool EvalConditionAnnotated(const Condition *cond, Mutex *mu, // Note: we can't simply do POST_LOCK, Eval, PRE_LOCK, because then tsan // will think the lock acquisition is recursive which will trigger // deadlock detector. - ABSL_TSAN_MUTEX_POST_LOCK(mu, TsanFlags(how), 0); + ABSL_TSAN_MUTEX_POST_LOCK(mu, tryflags, 0); res = cond->Eval(); - ABSL_TSAN_MUTEX_PRE_UNLOCK(mu, TsanFlags(how)); - ABSL_TSAN_MUTEX_POST_UNLOCK(mu, TsanFlags(how)); - ABSL_TSAN_MUTEX_PRE_LOCK(mu, TsanFlags(how)); + // There is no "try" version of Unlock, so use flags instead of tryflags. + ABSL_TSAN_MUTEX_PRE_UNLOCK(mu, flags); + ABSL_TSAN_MUTEX_POST_UNLOCK(mu, flags); + ABSL_TSAN_MUTEX_PRE_LOCK(mu, tryflags); } else { // Similarly, for unlock we pretend that we have unlocked the mutex, // lock the mutex, evaluate the predicate, and start unlocking it again // to match the annotation at the end of outer unlock operation. - ABSL_TSAN_MUTEX_POST_UNLOCK(mu, TsanFlags(how)); - ABSL_TSAN_MUTEX_PRE_LOCK(mu, TsanFlags(how)); - ABSL_TSAN_MUTEX_POST_LOCK(mu, TsanFlags(how), 0); + ABSL_TSAN_MUTEX_POST_UNLOCK(mu, flags); + ABSL_TSAN_MUTEX_PRE_LOCK(mu, flags); + ABSL_TSAN_MUTEX_POST_LOCK(mu, flags, 0); res = cond->Eval(); - ABSL_TSAN_MUTEX_PRE_UNLOCK(mu, TsanFlags(how)); + ABSL_TSAN_MUTEX_PRE_UNLOCK(mu, flags); } // Prevent unused param warnings in non-TSAN builds. static_cast<void>(mu); - static_cast<void>(how); + static_cast<void>(trylock); + static_cast<void>(read_lock); return res; } @@ -1807,7 +1834,8 @@ bool Mutex::LockSlowWithDeadline(MuHow how, const Condition *cond, v, (how->fast_or | (v & zap_desig_waker[flags & kMuHasBlocked])) + how->fast_add, std::memory_order_acquire, std::memory_order_relaxed)) { - if (cond == nullptr || EvalConditionAnnotated(cond, this, true, how)) { + if (cond == nullptr || + EvalConditionAnnotated(cond, this, true, false, how == kShared)) { return true; } unlock = true; @@ -1825,7 +1853,8 @@ bool Mutex::LockSlowWithDeadline(MuHow how, const Condition *cond, } this->LockSlowLoop(&waitp, flags); return waitp.cond != nullptr || // => cond known true from LockSlowLoop - cond == nullptr || EvalConditionAnnotated(cond, this, true, how); + cond == nullptr || + EvalConditionAnnotated(cond, this, true, false, how == kShared); } // RAW_CHECK_FMT() takes a condition, a printf-style format string, and @@ -1881,7 +1910,8 @@ void Mutex::LockSlowLoop(SynchWaitParams *waitp, int flags) { waitp->how->fast_add, std::memory_order_acquire, std::memory_order_relaxed)) { if (waitp->cond == nullptr || - EvalConditionAnnotated(waitp->cond, this, true, waitp->how)) { + EvalConditionAnnotated(waitp->cond, this, true, false, + waitp->how == kShared)) { break; // we timed out, or condition true, so return } this->UnlockSlow(waitp); // got lock but condition false @@ -1924,7 +1954,8 @@ void Mutex::LockSlowLoop(SynchWaitParams *waitp, int flags) { std::memory_order_release, std::memory_order_relaxed)); if (waitp->cond == nullptr || - EvalConditionAnnotated(waitp->cond, this, true, waitp->how)) { + EvalConditionAnnotated(waitp->cond, this, true, false, + waitp->how == kShared)) { break; // we timed out, or condition true, so return } this->UnlockSlow(waitp); // got lock but condition false |