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| author | Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> | 2020-05-20 15:35:03 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-05-20 08:41:26 -0600 |
| commit | 6b668c9b7fc6fc0c313cdaee8b75d17f4d954ab5 (patch) | |
| tree | 2e3467201427f4f9fd45ceab17077f3aa5fafa10 /fs/io_uring.c | |
| parent | 310672552f4aea2ad50704711aa3cdd45f5441e9 (diff) | |
| download | lwn-6b668c9b7fc6fc0c313cdaee8b75d17f4d954ab5.tar.gz lwn-6b668c9b7fc6fc0c313cdaee8b75d17f4d954ab5.zip | |
io_uring: don't submit sqes when ctx->refs is dying
When IORING_SETUP_SQPOLL is enabled, io_ring_ctx_wait_and_kill() will wait
for sq thread to idle by busy loop:
while (ctx->sqo_thread && !wq_has_sleeper(&ctx->sqo_wait))
cond_resched();
Above loop isn't very CPU friendly, it may introduce a short cpu burst on
the current cpu.
If ctx->refs is dying, we forbid sq_thread from submitting any further
SQEs. Instead they just get discarded when we exit.
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 13 |
1 files changed, 2 insertions, 11 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 50f079417911..0b51f21e5432 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -6175,7 +6175,8 @@ static int io_sq_thread(void *data) } mutex_lock(&ctx->uring_lock); - ret = io_submit_sqes(ctx, to_submit, NULL, -1); + if (likely(!percpu_ref_is_dying(&ctx->refs))) + ret = io_submit_sqes(ctx, to_submit, NULL, -1); mutex_unlock(&ctx->uring_lock); timeout = jiffies + ctx->sq_thread_idle; } @@ -7465,16 +7466,6 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx) percpu_ref_kill(&ctx->refs); mutex_unlock(&ctx->uring_lock); - /* - * Wait for sq thread to idle, if we have one. It won't spin on new - * work after we've killed the ctx ref above. This is important to do - * before we cancel existing commands, as the thread could otherwise - * be queueing new work post that. If that's work we need to cancel, - * it could cause shutdown to hang. - */ - while (ctx->sqo_thread && !wq_has_sleeper(&ctx->sqo_wait)) - cond_resched(); - io_kill_timeouts(ctx); io_poll_remove_all(ctx); |