Don't wake the master task after queueing a deferred tw unless it's
currently waiting in io_cqring_wait.
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
include/linux/io_uring_types.h | 1 +
io_uring/io_uring.c | 6 +++++-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 1452ff745e5c..332a29cfe076 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -285,6 +285,7 @@ struct io_ring_ctx {
unsigned cached_cq_tail;
unsigned cq_entries;
+ bool cq_waiting;
struct io_ev_fd __rcu *io_ev_fd;
struct wait_queue_head cq_wait;
struct wait_queue_head poll_wq;
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 943032d2fd21..e436fe73becf 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1275,7 +1275,8 @@ static void io_req_local_work_add(struct io_kiocb *req)
io_eventfd_signal(ctx);
if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
- wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE);
+ if (READ_ONCE(ctx->cq_waiting))
+ wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE);
} else {
__io_cqring_wake(ctx);
}
@@ -2565,6 +2566,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
set_current_state(TASK_INTERRUPTIBLE);
+ smp_store_mb(ctx->cq_waiting, 1);
} else {
prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
TASK_INTERRUPTIBLE);
@@ -2572,6 +2574,8 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
ret = io_cqring_wait_schedule(ctx, &iowq, timeout);
__set_current_state(TASK_RUNNING);
+ WRITE_ONCE(ctx->cq_waiting, 0);
+
if (ret < 0)
break;
/*
--
2.38.1
