From: Jens Axboe axboe@kernel.dk
[ Upstream commit ca0a26511c679a797f86589894a4523db36d833e ]
It doesn't make sense to wait for more events to come in, if we can't even flush the overflow we already have to the ring. Return -EBUSY for that condition, just like we do for attempts to submit with overflow pending.
Cc: stable@vger.kernel.org # 5.11 Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- fs/io_uring.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 7621978e9fc8..cab380a337e4 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1823,18 +1823,22 @@ static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, return all_flushed; }
-static void io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, +static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, struct task_struct *tsk, struct files_struct *files) { + bool ret = true; + if (test_bit(0, &ctx->cq_check_overflow)) { /* iopoll syncs against uring_lock, not completion_lock */ if (ctx->flags & IORING_SETUP_IOPOLL) mutex_lock(&ctx->uring_lock); - __io_cqring_overflow_flush(ctx, force, tsk, files); + ret = __io_cqring_overflow_flush(ctx, force, tsk, files); if (ctx->flags & IORING_SETUP_IOPOLL) mutex_unlock(&ctx->uring_lock); } + + return ret; }
static void __io_cqring_fill_event(struct io_kiocb *req, long res, long cflags) @@ -7280,11 +7284,16 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts); trace_io_uring_cqring_wait(ctx, min_events); do { - io_cqring_overflow_flush(ctx, false, NULL, NULL); + /* if we can't even flush overflow, don't wait for more */ + if (!io_cqring_overflow_flush(ctx, false, NULL, NULL)) { + ret = -EBUSY; + break; + } prepare_to_wait_exclusive(&ctx->wait, &iowq.wq, TASK_INTERRUPTIBLE); ret = io_cqring_wait_schedule(ctx, &iowq, &timeout); finish_wait(&ctx->wait, &iowq.wq); + cond_resched(); } while (ret > 0);
restore_saved_sigmask_unless(ret == -EINTR);