[glibc] malloc: Use C11 atomics rather than atomic_exchange_and_add

[Wilco Dijkstra <wilco@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=89d40cacd0aed35e2546513ce01924b879523e46

commit 89d40cacd0aed35e2546513ce01924b879523e46
Author: Wilco Dijkstra <wdijkstr@arm.com>
Date:   Tue Sep 6 16:49:01 2022 +0100

    malloc: Use C11 atomics rather than atomic_exchange_and_add
    
    Replace a few counters using atomic_exchange_and_add with
    atomic_fetch_add_relaxed.
    
    Reviewed-by: Florian Weimer <fweimer@redhat.com>

Diff:
---
 malloc/malloc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/malloc/malloc.c b/malloc/malloc.c
index 29fa71b3b2..ecec901b14 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -2460,11 +2460,11 @@ sysmalloc_mmap (INTERNAL_SIZE_T nb, size_t pagesize, int extra_flags, mstate av)
     }
 
   /* update statistics */
-  int new = atomic_exchange_and_add (&mp_.n_mmaps, 1) + 1;
+  int new = atomic_fetch_add_relaxed (&mp_.n_mmaps, 1) + 1;
   atomic_max (&mp_.max_n_mmaps, new);
 
   unsigned long sum;
-  sum = atomic_exchange_and_add (&mp_.mmapped_mem, size) + size;
+  sum = atomic_fetch_add_relaxed (&mp_.mmapped_mem, size) + size;
   atomic_max (&mp_.max_mmapped_mem, sum);
 
   check_chunk (av, p);
@@ -3084,7 +3084,7 @@ mremap_chunk (mchunkptr p, size_t new_size)
   set_head (p, (new_size - offset) | IS_MMAPPED);
 
   INTERNAL_SIZE_T new;
-  new = atomic_exchange_and_add (&mp_.mmapped_mem, new_size - size - offset)
+  new = atomic_fetch_add_relaxed (&mp_.mmapped_mem, new_size - size - offset)
         + new_size - size - offset;
   atomic_max (&mp_.max_mmapped_mem, new);
   return p;