diff options
Diffstat (limited to 'io_uring/io_uring.c')
| -rw-r--r-- | io_uring/io_uring.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index d40c767a6216..3ab7e6a46149 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1332,6 +1332,14 @@ static inline void io_req_local_work_add(struct io_kiocb *req, unsigned flags) } while (!try_cmpxchg(&ctx->work_llist.first, &first, &req->io_task_work.node)); + /* + * cmpxchg implies a full barrier, which pairs with the barrier + * in set_current_state() on the io_cqring_wait() side. It's used + * to ensure that either we see updated ->cq_wait_nr, or waiters + * going to sleep will observe the work added to the list, which + * is similar to the wait/wawke task state sync. + */ + if (!first) { if (ctx->flags & IORING_SETUP_TASKRUN_FLAG) atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags); @@ -1346,8 +1354,6 @@ static inline void io_req_local_work_add(struct io_kiocb *req, unsigned flags) /* either not enough or the previous add has already woken it up */ if (nr_wait > nr_tw || nr_tw_prev >= nr_wait) return; - /* pairs with set_current_state() in io_cqring_wait() */ - smp_mb__after_atomic(); wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE); } |