From: Jens Axboe <axboe@xxxxxxxxx>
[ 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@xxxxxxxxxxxxxxx # 5.11
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
--
2.30.1
