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| -rw-r--r-- | ChangeLog | 6 | ||||
| -rw-r--r-- | sysdeps/nptl/lowlevellock.h | 13 |
2 files changed, 14 insertions, 5 deletions
diff --git a/ChangeLog b/ChangeLog index 1f1cf0a049..a081ea4195 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2018-05-04 Stefan Liebler <stli@linux.vnet.ibm.com> + + [BZ #23137] + * sysdeps/nptl/lowlevellock.h (lll_wait_tid): + Use atomic_load_acquire to load __tid. + 2018-05-02 H.J. Lu <hongjiu.lu@intel.com> * sysdeps/unix/sysv/linux/x86_64/swapcontext.S (__swapcontext): diff --git a/sysdeps/nptl/lowlevellock.h b/sysdeps/nptl/lowlevellock.h index 8326e2805c..bfbda99940 100644 --- a/sysdeps/nptl/lowlevellock.h +++ b/sysdeps/nptl/lowlevellock.h @@ -181,11 +181,14 @@ extern int __lll_timedlock_wait (int *futex, const struct timespec *, thread ID while the clone is running and is reset to zero by the kernel afterwards. The kernel up to version 3.16.3 does not use the private futex operations for futex wake-up when the clone terminates. */ -#define lll_wait_tid(tid) \ - do { \ - __typeof (tid) __tid; \ - while ((__tid = (tid)) != 0) \ - lll_futex_wait (&(tid), __tid, LLL_SHARED);\ +#define lll_wait_tid(tid) \ + do { \ + __typeof (tid) __tid; \ + /* We need acquire MO here so that we synchronize \ + with the kernel's store to 0 when the clone \ + terminates. (see above) */ \ + while ((__tid = atomic_load_acquire (&(tid))) != 0) \ + lll_futex_wait (&(tid), __tid, LLL_SHARED); \ } while (0) extern int __lll_timedwait_tid (int *, const struct timespec *) |