From: Pavel Begunkov asml.silence@gmail.com
[ Upstream commit eeb60b9ab4000d20261973642dfc9fb0e4b5d073 ]
It's easy to make a mistake in io_cqring_wait() because for all break/continue clauses we need to watch for prepare/finish_wait to be used correctly. Extract all those into a new helper io_cqring_wait_schedule(), and transforming the loop into simple series of func calls: prepare(); check_and_schedule(); finish();
Signed-off-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- fs/io_uring.c | 43 ++++++++++++++++++++++--------------------- 1 file changed, 22 insertions(+), 21 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 3e610ac062a3..7621978e9fc8 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7208,6 +7208,25 @@ static int io_run_task_work_sig(void) return -EINTR; }
+/* when returns >0, the caller should retry */ +static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx, + struct io_wait_queue *iowq, + signed long *timeout) +{ + int ret; + + /* make sure we run task_work before checking for signals */ + ret = io_run_task_work_sig(); + if (ret || io_should_wake(iowq)) + return ret; + /* let the caller flush overflows, retry */ + if (test_bit(0, &ctx->cq_check_overflow)) + return 1; + + *timeout = schedule_timeout(*timeout); + return !*timeout ? -ETIME : 1; +} + /* * Wait until events become available, if we don't already have some. The * application must reap them itself, as they reside on the shared cq ring. @@ -7264,27 +7283,9 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, io_cqring_overflow_flush(ctx, false, NULL, NULL); prepare_to_wait_exclusive(&ctx->wait, &iowq.wq, TASK_INTERRUPTIBLE); - /* make sure we run task_work before checking for signals */ - ret = io_run_task_work_sig(); - if (ret > 0) { - finish_wait(&ctx->wait, &iowq.wq); - continue; - } - else if (ret < 0) - break; - if (io_should_wake(&iowq)) - break; - if (test_bit(0, &ctx->cq_check_overflow)) { - finish_wait(&ctx->wait, &iowq.wq); - continue; - } - timeout = schedule_timeout(timeout); - if (timeout == 0) { - ret = -ETIME; - break; - } - } while (1); - finish_wait(&ctx->wait, &iowq.wq); + ret = io_cqring_wait_schedule(ctx, &iowq, &timeout); + finish_wait(&ctx->wait, &iowq.wq); + } while (ret > 0);
restore_saved_sigmask_unless(ret == -EINTR);