io_uring: don't save/restore iowait state

[ Upstream commit 6f0974eccbf78baead1735722c4f1ee3eb9422cd ]

This kind of state is per-syscall, and since we're doing the waiting off
entering the io_uring_enter(2) syscall, there's no way that iowait can
already be set for this case. Simplify it by setting it if we need to,
and always clearing it to 0 when done.

Fixes: 7b72d661f1f2 ("io_uring: gate iowait schedule on having pending requests")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index b658ba6703cc20f05a429d53462746e685016058..205dad96037331f5c5e6929149cee147fb1c4f09 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2508,7 +2508,7 @@ static bool current_pending_io(void)
 static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
                                          struct io_wait_queue *iowq)
 {
-       int io_wait, ret;
+       int ret;
 
        if (unlikely(READ_ONCE(ctx->check_cq)))
                return 1;
@@ -2526,7 +2526,6 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
         * can take into account that the task is waiting for IO - turns out
         * to be important for low QD IO.
         */
-       io_wait = current->in_iowait;
        if (current_pending_io())
                current->in_iowait = 1;
        ret = 0;
@@ -2534,7 +2533,7 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
                schedule();
        else if (!schedule_hrtimeout(&iowq->timeout, HRTIMER_MODE_ABS))
                ret = -ETIME;
-       current->in_iowait = io_wait;
+       current->in_iowait = 0;
        return ret;
 }