diff options
| author | Hao Xu <haoxu@linux.alibaba.com> | 2021-08-21 01:19:54 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-08-23 22:10:46 +0300 |
| commit | 99c8bc52d1321ab3a711eba2941eadbe7425230f (patch) | |
| tree | 0bbbe1f3d0adb68888e119468af7801425e136e3 /fs/io_uring.c | |
| parent | 187f08c12cd1d81f000cdc9c0119ef6e0a6f47e3 (diff) | |
| download | linux-99c8bc52d1321ab3a711eba2941eadbe7425230f.tar.xz | |
io_uring: fix lack of protection for compl_nr
coml_nr in ctx_flush_and_put() is not protected by uring_lock, this
may cause problems when accessing in parallel:
say coml_nr > 0
ctx_flush_and put other context
if (compl_nr) get mutex
coml_nr > 0
do flush
coml_nr = 0
release mutex
get mutex
do flush (*)
release mutex
in (*) place, we call io_cqring_ev_posted() and users likely get
no events there. To avoid spurious events, re-check the value when
under the lock.
Fixes: 2c32395d8111 ("io_uring: fix __tctx_task_work() ctx race")
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20210820221954.61815-1-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 | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 5d3df4f913a8..706ac8c03b95 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2007,7 +2007,8 @@ static void ctx_flush_and_put(struct io_ring_ctx *ctx) return; if (ctx->submit_state.compl_nr) { mutex_lock(&ctx->uring_lock); - io_submit_flush_completions(ctx); + if (ctx->submit_state.compl_nr) + io_submit_flush_completions(ctx); mutex_unlock(&ctx->uring_lock); } percpu_ref_put(&ctx->refs); |