Mercurial > hg > nginx
comparison src/core/ngx_thread_pool.c @ 6517:657e029bac28
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.
| author | Maxim Dounin <mdounin@mdounin.ru> |
|---|---|
| date | Tue, 19 Apr 2016 17:18:28 +0300 |
| parents | abde398f34a7 |
| children | 33d075b9097d |
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| 6516:ab16126a06a0 | 6517:657e029bac28 |
|---|---|
| 343 ngx_spinlock(&ngx_thread_pool_done_lock, 1, 2048); | 343 ngx_spinlock(&ngx_thread_pool_done_lock, 1, 2048); |
| 344 | 344 |
| 345 *ngx_thread_pool_done.last = task; | 345 *ngx_thread_pool_done.last = task; |
| 346 ngx_thread_pool_done.last = &task->next; | 346 ngx_thread_pool_done.last = &task->next; |
| 347 | 347 |
| 348 ngx_memory_barrier(); | |
| 349 | |
| 348 ngx_unlock(&ngx_thread_pool_done_lock); | 350 ngx_unlock(&ngx_thread_pool_done_lock); |
| 349 | 351 |
| 350 (void) ngx_notify(ngx_thread_pool_handler); | 352 (void) ngx_notify(ngx_thread_pool_handler); |
| 351 } | 353 } |
| 352 } | 354 } |
| 363 ngx_spinlock(&ngx_thread_pool_done_lock, 1, 2048); | 365 ngx_spinlock(&ngx_thread_pool_done_lock, 1, 2048); |
| 364 | 366 |
| 365 task = ngx_thread_pool_done.first; | 367 task = ngx_thread_pool_done.first; |
| 366 ngx_thread_pool_done.first = NULL; | 368 ngx_thread_pool_done.first = NULL; |
| 367 ngx_thread_pool_done.last = &ngx_thread_pool_done.first; | 369 ngx_thread_pool_done.last = &ngx_thread_pool_done.first; |
| 370 | |
| 371 ngx_memory_barrier(); | |
| 368 | 372 |
| 369 ngx_unlock(&ngx_thread_pool_done_lock); | 373 ngx_unlock(&ngx_thread_pool_done_lock); |
| 370 | 374 |
| 371 while (task) { | 375 while (task) { |
| 372 ngx_log_debug1(NGX_LOG_DEBUG_CORE, ev->log, 0, | 376 ngx_log_debug1(NGX_LOG_DEBUG_CORE, ev->log, 0, |