diff options
| author | Hao Xu <haoxu@linux.alibaba.com> | 2021-04-21 23:19:11 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-04-23 08:26:41 -0600 |
| commit | 724cb4f9ec905173f32c5bd08fec26abaecc6a1d (patch) | |
| tree | 3f45081913cc810132a9b2596a0af98b87d957a3 /fs/io_uring.c | |
| parent | f2a48dd09b8e933f59570692e1382b81d4fddc49 (diff) | |
io_uring: check sqring and iopoll_list before shedule
do this to avoid race below:
userspace kernel
| check sqring and iopoll_list
submit sqe |
check IORING_SQ_NEED_WAKEUP |
(which is not set) | |
| set IORING_SQ_NEED_WAKEUP
wait cqe | schedule(never wakeup again)
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/1619018351-75883-1-git-send-email-haoxu@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 | 36 |
1 files changed, 19 insertions, 17 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 2d49197845e8..40f38256499c 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -6839,27 +6839,29 @@ static int io_sq_thread(void *data) continue; } - needs_sched = true; prepare_to_wait(&sqd->wait, &wait, TASK_INTERRUPTIBLE); - list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) { - if ((ctx->flags & IORING_SETUP_IOPOLL) && - !list_empty_careful(&ctx->iopoll_list)) { - needs_sched = false; - break; - } - if (io_sqring_entries(ctx)) { - needs_sched = false; - break; - } - } - - if (needs_sched && !test_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state)) { + if (!test_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state)) { list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) io_ring_set_wakeup_flag(ctx); - mutex_unlock(&sqd->lock); - schedule(); - mutex_lock(&sqd->lock); + needs_sched = true; + list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) { + if ((ctx->flags & IORING_SETUP_IOPOLL) && + !list_empty_careful(&ctx->iopoll_list)) { + needs_sched = false; + break; + } + if (io_sqring_entries(ctx)) { + needs_sched = false; + break; + } + } + + if (needs_sched) { + mutex_unlock(&sqd->lock); + schedule(); + mutex_lock(&sqd->lock); + } list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) io_ring_clear_wakeup_flag(ctx); } |