io_uring: fix CQ waiting timeout handling

commit 12521a5d5cb7ff0ad43eadfc9c135d86e1131fa8 upstream.

Jiffy to ktime CQ waiting conversion broke how we treat timeouts, in
particular we rearm it anew every time we get into
io_cqring_wait_schedule() without adjusting the timeout. Waiting for 2
CQEs and getting a task_work in the middle may double the timeout value,
or even worse in some cases task may wait indefinitely.

Cc: stable@vger.kernel.org
Fixes: 228339662b398 ("io_uring: don't convert to jiffies for waiting on timeouts")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f7bffddd71b08f28a877d44d37ac953ddb01590d.1672915663.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index c93e988..cea5de9 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2364,7 +2364,7 @@ int io_run_task_work_sig(struct io_ring_ctx *ctx)
 /* when returns >0, the caller should retry */
 static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
                                          struct io_wait_queue *iowq,
-                                         ktime_t timeout)
+                                         ktime_t *timeout)
 {
        int ret;
        unsigned long check_cq;
@@ -2382,7 +2382,7 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
                if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT))
                        return -EBADR;
        }
-       if (!schedule_hrtimeout(&timeout, HRTIMER_MODE_ABS))
+       if (!schedule_hrtimeout(timeout, HRTIMER_MODE_ABS))
                return -ETIME;
        return 1;
 }
@@ -2452,7 +2452,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
                }
                prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
                                                TASK_INTERRUPTIBLE);
-               ret = io_cqring_wait_schedule(ctx, &iowq, timeout);
+               ret = io_cqring_wait_schedule(ctx, &iowq, &timeout);
                cond_resched();
        } while (ret > 0);