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1660901840
On s390 (31bit) if glibc is build with -Os, pthread_join sometimes blocks indefinitely. This is e.g. observable with testcase intl/tst-gettext6. pthread_join is calling lll_wait_tid(tid), which performs the futex-wait syscall in a loop as long as tid != 0 (thread is alive). On s390 (and build with -Os), tid is loaded from memory before comparing against zero and then the tid is loaded a second time in order to pass it to the futex-wait-syscall. If the thread exits in between, then the futex-wait-syscall is called with the value zero and it waits until a futex-wake occurs. As the thread is already exited, there won't be a futex-wake. In lll_wait_tid, the tid is stored to the local variable __tid, which is then used as argument for the futex-wait-syscall. But unfortunately the compiler is allowed to reload the value from memory. With this patch, the tid is loaded with atomic_load_acquire. Then the compiler is not allowed to reload the value for __tid from memory. ChangeLog: [BZ #23137] * sysdeps/nptl/lowlevellock.h (lll_wait_tid): Use atomic_load_acquire to load __tid. |
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| .. | ||
| bits | ||
| sys | ||
| aio_misc.h | ||
| allocrtsig.c | ||
| fork.c | ||
| fork.h | ||
| futex-internal.h | ||
| gai_misc.h | ||
| Implies | ||
| internaltypes.h | ||
| jmp-unwind.c | ||
| libc-lock.h | ||
| libc-lockP.h | ||
| librt-cancellation.c | ||
| lowlevellock-futex.h | ||
| lowlevellock.h | ||
| Makeconfig | ||
| Makefile | ||
| malloc-machine.h | ||
| pthread-functions.h | ||
| pthread.h | ||
| setxid.h | ||
| shm-directory.h | ||
| stdio-lock.h | ||
| Subdirs | ||
| tcb-offsets.h | ||
| timer_routines.h | ||
| tst-mqueue8x.c | ||
| unwind-forcedunwind.c | ||