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Diffstat (limited to 'absl/synchronization/mutex.cc')
-rw-r--r--absl/synchronization/mutex.cc107
1 files changed, 69 insertions, 38 deletions
diff --git a/absl/synchronization/mutex.cc b/absl/synchronization/mutex.cc
index 6b2eb331..37ffff3d 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
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-08 20:12:27 +0000