details: http://hg.nginx.org/nginx/rev/657e029bac28 branches: changeset: 6517:657e029bac28 user: Maxim Dounin <mdou...@mdounin.ru> date: Tue Apr 19 17:18:28 2016 +0300 description: Thread pools: memory barriers in task completion notifications.
The ngx_thread_pool_done object isn't volatile, and at least some compilers assume that it is permitted to reorder modifications of volatile and non-volatile objects. Added appropriate ngx_memory_barrier() calls to make sure all modifications will happen before the lock is released. Reported by Mindaugas Rasiukevicius, http://mailman.nginx.org/pipermail/nginx-devel/2016-April/008160.html. diffstat: src/core/ngx_thread_pool.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diffs (21 lines): diff --git a/src/core/ngx_thread_pool.c b/src/core/ngx_thread_pool.c --- a/src/core/ngx_thread_pool.c +++ b/src/core/ngx_thread_pool.c @@ -345,6 +345,8 @@ ngx_thread_pool_cycle(void *data) *ngx_thread_pool_done.last = task; ngx_thread_pool_done.last = &task->next; + ngx_memory_barrier(); + ngx_unlock(&ngx_thread_pool_done_lock); (void) ngx_notify(ngx_thread_pool_handler); @@ -366,6 +368,8 @@ ngx_thread_pool_handler(ngx_event_t *ev) ngx_thread_pool_done.first = NULL; ngx_thread_pool_done.last = &ngx_thread_pool_done.first; + ngx_memory_barrier(); + ngx_unlock(&ngx_thread_pool_done_lock); while (task) { _______________________________________________ nginx-devel mailing list nginx-devel@nginx.org http://mailman.nginx.org/mailman/listinfo/nginx-devel