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65810f0ef0
lll_robust_unlock on i386 and x86_64 first sets the futex word to FUTEX_WAITERS|0 before calling __lll_unlock_wake, which will set the futex word to 0. If the thread is killed between these steps, then the futex word will be FUTEX_WAITERS|0, and the kernel (at least current upstream) will not set it to FUTEX_OWNER_DIED|FUTEX_WAITERS because 0 is not equal to the TID of the crashed thread. The lll_robust_lock assembly code on i386 and x86_64 is not prepared to deal with this case because the fastpath tries to only CAS 0 to TID and not FUTEX_WAITERS|0 to TID; the slowpath simply waits until it can CAS 0 to TID or the futex_word has the FUTEX_OWNER_DIED bit set. This issue is fixed by removing the custom x86 assembly code and using the generic C code instead. However, instead of adding more duplicate code to the custom x86 lowlevellock.h, the code of the lll_robust* functions is inlined into the single call sites that exist for each of these functions in the pthread_mutex_* functions. The robust mutex paths in the latter have been slightly reorganized to make them simpler. This patch is meant to be easy to backport, so C11-style atomics are not used. [BZ #20985] * nptl/Makefile: Adapt. * nptl/pthread_mutex_cond_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove. (LLL_ROBUST_MUTEX_LOCK_MODIFIER): New. * nptl/pthread_mutex_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove. (LLL_ROBUST_MUTEX_LOCK_MODIFIER): New. (__pthread_mutex_lock_full): Inline lll_robust* functions and adapt. * nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Inline lll_robust* functions and adapt. * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise. * sysdeps/nptl/lowlevellock.h (__lll_robust_lock_wait, __lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait, __lll_robust_timedlock, __lll_robust_unlock): Remove. * sysdeps/unix/sysv/linux/i386/lowlevellock.h (lll_robust_lock, lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove. * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h (lll_robust_lock, lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove. * sysdeps/unix/sysv/linux/sparc/lowlevellock.h (__lll_robust_lock_wait, __lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait, __lll_robust_timedlock, __lll_robust_unlock): Remove. * nptl/lowlevelrobustlock.c: Remove file. * nptl/lowlevelrobustlock.sym: Likewise. * sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S: Likewise. * sysdeps/unix/sysv/linux/x86_64/lowlevelrobustlock.S: Likewise. |
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| .. | ||
| 64 | ||
| x32 | ||
| ____longjmp_chk.S | ||
| __start_context.S | ||
| arch-fork.h | ||
| brk.c | ||
| cancellation.S | ||
| clone.S | ||
| compat-timer.h | ||
| configure | ||
| configure.ac | ||
| dl-cache.h | ||
| dl-procinfo.c | ||
| dl-procinfo.h | ||
| get_clockfreq.c | ||
| getcontext.S | ||
| Implies | ||
| init-first.c | ||
| ipc_priv.h | ||
| kernel_stat.h | ||
| kernel-features.h | ||
| ldconfig.h | ||
| ldd-rewrite.sed | ||
| libc-cancellation.S | ||
| libc-lowlevellock.S | ||
| libmvec.abilist | ||
| librt-cancellation.S | ||
| lll_timedlock_wait.c | ||
| lll_timedwait_tid.c | ||
| lowlevellock.h | ||
| lowlevellock.S | ||
| makecontext.c | ||
| Makefile | ||
| profil-counter.h | ||
| pthread_setaffinity.c | ||
| readelflib.c | ||
| recv.c | ||
| register-dump.h | ||
| sched_setaffinity.c | ||
| send.c | ||
| setcontext.S | ||
| sigaction.c | ||
| sigaltstack-offsets.sym | ||
| sigcontextinfo.h | ||
| sigpending.c | ||
| sigprocmask.c | ||
| swapcontext.S | ||
| syscall.S | ||
| syscalls.list | ||
| sysdep-cancel.h | ||
| sysdep.h | ||
| sysdep.S | ||
| timer_create.c | ||
| timer_delete.c | ||
| timer_getoverr.c | ||
| timer_gettime.c | ||
| timer_settime.c | ||
| ucontext_i.sym | ||
| umount.c | ||
| Versions | ||
| vfork.S | ||