forked from pool/glibc
afe7a231ef
- pthread-rwlock-trylock-stalls.patch: nptl: Fix pthread_rwlock_try*lock stalls (BZ #23844) - arm-systemtap-probe-constraint.patch: arm: Use "nr" constraint for Systemtap probes (BZ #24164) - pthread-mutex-barrier.patch: Add compiler barriers around modifications of the robust mutex list for pthread_mutex_trylock (BZ #24180) - fork-handler-lock.patch: nptl: Avoid fork handler lock for async-signal-safe fork (BZ #24161) - pthread-join-probe.patch: nptl: Fix invalid Systemtap probe in pthread_join (BZ #24211) - riscv-clone-unwind.patch: RISC-V: Fix elfutils testsuite unwind failures (BZ #24040) OBS-URL: https://build.opensuse.org/request/show/677136 OBS-URL: https://build.opensuse.org/package/show/Base:System/glibc?expand=0&rev=518
174 lines
6.4 KiB
Diff
174 lines
6.4 KiB
Diff
2019-02-07 Stefan Liebler <stli@linux.ibm.com>
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[BZ #24180]
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* nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock):
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Add compiler barriers and comments.
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Index: glibc-2.29/nptl/pthread_mutex_trylock.c
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===================================================================
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--- glibc-2.29.orig/nptl/pthread_mutex_trylock.c
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+++ glibc-2.29/nptl/pthread_mutex_trylock.c
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@@ -94,6 +94,9 @@ __pthread_mutex_trylock (pthread_mutex_t
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case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
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&mutex->__data.__list.__next);
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+ /* We need to set op_pending before starting the operation. Also
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+ see comments at ENQUEUE_MUTEX. */
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+ __asm ("" ::: "memory");
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oldval = mutex->__data.__lock;
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do
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@@ -119,7 +122,12 @@ __pthread_mutex_trylock (pthread_mutex_t
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/* But it is inconsistent unless marked otherwise. */
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mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
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+ /* We must not enqueue the mutex before we have acquired it.
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+ Also see comments at ENQUEUE_MUTEX. */
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+ __asm ("" ::: "memory");
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ENQUEUE_MUTEX (mutex);
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+ /* We need to clear op_pending after we enqueue the mutex. */
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+ __asm ("" ::: "memory");
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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/* Note that we deliberately exist here. If we fall
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@@ -135,6 +143,8 @@ __pthread_mutex_trylock (pthread_mutex_t
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int kind = PTHREAD_MUTEX_TYPE (mutex);
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if (kind == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
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{
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+ /* We do not need to ensure ordering wrt another memory
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+ access. Also see comments at ENQUEUE_MUTEX. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
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NULL);
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return EDEADLK;
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@@ -142,6 +152,8 @@ __pthread_mutex_trylock (pthread_mutex_t
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if (kind == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
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{
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+ /* We do not need to ensure ordering wrt another memory
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+ access. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
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NULL);
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@@ -160,6 +172,9 @@ __pthread_mutex_trylock (pthread_mutex_t
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id, 0);
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if (oldval != 0 && (oldval & FUTEX_OWNER_DIED) == 0)
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{
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+ /* We haven't acquired the lock as it is already acquired by
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+ another owner. We do not need to ensure ordering wrt another
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+ memory access. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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return EBUSY;
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@@ -173,13 +188,20 @@ __pthread_mutex_trylock (pthread_mutex_t
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if (oldval == id)
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lll_unlock (mutex->__data.__lock,
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PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
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+ /* FIXME This violates the mutex destruction requirements. See
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+ __pthread_mutex_unlock_full. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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return ENOTRECOVERABLE;
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}
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}
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while ((oldval & FUTEX_OWNER_DIED) != 0);
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+ /* We must not enqueue the mutex before we have acquired it.
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+ Also see comments at ENQUEUE_MUTEX. */
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+ __asm ("" ::: "memory");
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ENQUEUE_MUTEX (mutex);
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+ /* We need to clear op_pending after we enqueue the mutex. */
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+ __asm ("" ::: "memory");
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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mutex->__data.__owner = id;
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@@ -211,10 +233,15 @@ __pthread_mutex_trylock (pthread_mutex_t
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}
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if (robust)
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- /* Note: robust PI futexes are signaled by setting bit 0. */
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- THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
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- (void *) (((uintptr_t) &mutex->__data.__list.__next)
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- | 1));
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+ {
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+ /* Note: robust PI futexes are signaled by setting bit 0. */
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+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
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+ (void *) (((uintptr_t) &mutex->__data.__list.__next)
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+ | 1));
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+ /* We need to set op_pending before starting the operation. Also
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+ see comments at ENQUEUE_MUTEX. */
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+ __asm ("" ::: "memory");
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+ }
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oldval = mutex->__data.__lock;
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@@ -223,12 +250,16 @@ __pthread_mutex_trylock (pthread_mutex_t
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{
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if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
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{
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+ /* We do not need to ensure ordering wrt another memory
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+ access. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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return EDEADLK;
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}
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if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
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{
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+ /* We do not need to ensure ordering wrt another memory
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+ access. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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/* Just bump the counter. */
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@@ -250,6 +281,9 @@ __pthread_mutex_trylock (pthread_mutex_t
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{
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if ((oldval & FUTEX_OWNER_DIED) == 0)
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{
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+ /* We haven't acquired the lock as it is already acquired by
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+ another owner. We do not need to ensure ordering wrt another
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+ memory access. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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return EBUSY;
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@@ -270,6 +304,9 @@ __pthread_mutex_trylock (pthread_mutex_t
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if (INTERNAL_SYSCALL_ERROR_P (e, __err)
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&& INTERNAL_SYSCALL_ERRNO (e, __err) == EWOULDBLOCK)
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{
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+ /* The kernel has not yet finished the mutex owner death.
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+ We do not need to ensure ordering wrt another memory
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+ access. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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return EBUSY;
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@@ -287,7 +324,12 @@ __pthread_mutex_trylock (pthread_mutex_t
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/* But it is inconsistent unless marked otherwise. */
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mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
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+ /* We must not enqueue the mutex before we have acquired it.
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+ Also see comments at ENQUEUE_MUTEX. */
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+ __asm ("" ::: "memory");
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ENQUEUE_MUTEX (mutex);
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+ /* We need to clear op_pending after we enqueue the mutex. */
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+ __asm ("" ::: "memory");
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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/* Note that we deliberately exit here. If we fall
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@@ -310,13 +352,20 @@ __pthread_mutex_trylock (pthread_mutex_t
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PTHREAD_ROBUST_MUTEX_PSHARED (mutex)),
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0, 0);
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+ /* To the kernel, this will be visible after the kernel has
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+ acquired the mutex in the syscall. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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return ENOTRECOVERABLE;
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}
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if (robust)
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{
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+ /* We must not enqueue the mutex before we have acquired it.
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+ Also see comments at ENQUEUE_MUTEX. */
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+ __asm ("" ::: "memory");
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ENQUEUE_MUTEX_PI (mutex);
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+ /* We need to clear op_pending after we enqueue the mutex. */
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+ __asm ("" ::: "memory");
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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}
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