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Use relaxed atomics since there is no MO dependence 

Replace the 3 uses of atomic_bit_set and atomic_bit_test_set with
atomic_fetch_or_relaxed.  Using relaxed MO is correct since the
atomics are used to ensure memory is released only once.

Reviewed-by: Florian Weimer <fweimer@redhat.com>
This commit is contained in:
Wilco Dijkstra 2022-09-13 11:58:07 +01:00
parent f278835f59
commit a30e960328
3 changed files with 4 additions and 9 deletions
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3
nptl/nptl_free_tcb.c
View File

@ -24,7 +24,8 @@ void
__nptl_free_tcb (struct pthread *pd)
{
/* The thread is exiting now. */
if (atomic_bit_test_set (&pd->cancelhandling, TERMINATED_BIT) == 0)
if ((atomic_fetch_or_relaxed (&pd->cancelhandling, TERMINATED_BITMASK)
& TERMINATED_BITMASK) == 0)
{
/* Free TPP data. */
if (pd->tpp != NULL)

2
nptl/pthread_create.c
View File

@ -487,7 +487,7 @@ start_thread (void *arg)
/* The thread is exiting now. Don't set this bit until after we've hit
the event-reporting breakpoint, so that td_thr_get_info on us while at
the breakpoint reports TD_THR_RUN state rather than TD_THR_ZOMBIE. */
atomic_bit_set (&pd->cancelhandling, EXITING_BIT);
atomic_fetch_or_relaxed (&pd->cancelhandling, EXITING_BITMASK);
if (__glibc_unlikely (atomic_decrement_and_test (&__nptl_nthreads)))
/* This was the last thread. */

8
sysdeps/nptl/pthreadP.h
View File

@ -43,12 +43,6 @@
atomic_compare_and_exchange_val_acq (&(descr)->member, new, old)
#endif
#ifndef THREAD_ATOMIC_BIT_SET
# define THREAD_ATOMIC_BIT_SET(descr, member, bit) \
atomic_bit_set (&(descr)->member, bit)
#endif
static inline short max_adaptive_count (void)
{
#if HAVE_TUNABLES
@ -276,7 +270,7 @@ __do_cancel (void)
struct pthread *self = THREAD_SELF;
/* Make sure we get no more cancellations. */
atomic_bit_set (&self->cancelhandling, EXITING_BIT);
atomic_fetch_or_relaxed (&self->cancelhandling, EXITING_BITMASK);
__pthread_unwind ((__pthread_unwind_buf_t *)
THREAD_GETMEM (self, cleanup_jmp_buf));