@@ -136,6 +136,7 @@ init_alloc_page (void)
#endif
static gtm_cacheline_page *free_pages;
+static pthread_mutex_t free_page_lock = PTHREAD_MUTEX_INITIALIZER;
void *
gtm_cacheline_page::operator new (size_t size)
@@ -143,19 +144,14 @@ gtm_cacheline_page::operator new (size_t size)
assert (size == sizeof (gtm_cacheline_page));
assert (size <= PAGE_SIZE);
+ pthread_mutex_lock(&free_page_lock);
+
gtm_cacheline_page *r = free_pages;
- restart:
- if (r)
- {
- gtm_cacheline_page *n, *p = r->prev;
- n = __sync_val_compare_and_swap (&free_pages, r, p);
- if (n != r)
- {
- r = n;
- goto restart;
- }
- }
- else
+ free_pages = r ? r->prev : NULL;
+
+ pthread_mutex_unlock(&free_page_lock);
+
+ if (r == NULL)
r = alloc_page ();
return r;
@@ -165,7 +161,7 @@ void
gtm_cacheline_page::operator delete (void *xhead)
{
gtm_cacheline_page *head = static_cast<gtm_cacheline_page *>(xhead);
- gtm_cacheline_page *tail, *n, *p;
+ gtm_cacheline_page *tail;
if (head == 0)
return;
@@ -175,15 +171,12 @@ gtm_cacheline_page::operator delete (void *xhead)
for (tail = head; tail->prev != 0; tail = tail->prev)
continue;
- p = free_pages;
- restart:
- tail->prev = p;
- n = __sync_val_compare_and_swap (&free_pages, p, head);
- if (n != p)
- {
- p = n;
- goto restart;
- }
+ pthread_mutex_lock(&free_page_lock);
+
+ tail->prev = free_pages;
+ free_pages = head;
+
+ pthread_mutex_unlock(&free_page_lock);
}
} // namespace GTM
Patrick Marlier pointed out that there was an ABA error in managing the page free list. Fixed by not trying to be so clever. r~ * config/posix/cachepage.cc (gtm_cacheline_page::operator new): Use a mutex instead of trying a lock-free compare-and-swap on the list. (gtm_cacheline_page::operator delete): Likewise.