[glibc] Use relaxed atomics since there is no MO dependence

[glibc] Use relaxed atomics since there is no MO dependence

[Wilco Dijkstra]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a30e960328fc60e066967d1224ecd5b6e173cda3

commit a30e960328fc60e066967d1224ecd5b6e173cda3
Author: Wilco Dijkstra <wdijkstr@arm.com>
Date:   Tue Sep 13 11:58:07 2022 +0100

    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>

Diff:
---
 nptl/nptl_free_tcb.c    | 3 ++-
 nptl/pthread_create.c   | 2 +-
 sysdeps/nptl/pthreadP.h | 8 +-------
 3 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/nptl/nptl_free_tcb.c b/nptl/nptl_free_tcb.c
index 0d31143ac8..86a8904898 100644
--- a/nptl/nptl_free_tcb.c
+++ b/nptl/nptl_free_tcb.c
@@ -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)
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index e7e4ede6b2..ee29cb375d 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -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.  */
diff --git a/sysdeps/nptl/pthreadP.h b/sysdeps/nptl/pthreadP.h
index 39af275c25..c8521b0b23 100644
--- a/sysdeps/nptl/pthreadP.h
+++ b/sysdeps/nptl/pthreadP.h
@@ -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));