[PATCH 5.15 287/317] io_uring: don't save/restore iowait state

Sasha Levin
2024-03-24T23:39:40Z

From: Jens Axboe <axboe@kernel.dk>

[ 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>
---
io_uring/io_uring.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 386b32e6fd9a8..a51429c0342e0 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -7815,7 +7815,7 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
struct io_wait_queue *iowq,
ktime_t *timeout)
{
- int io_wait, ret;
+ int ret;

/* make sure we run task_work before checking for signals */
ret = io_run_task_work_sig();
@@ -7830,13 +7830,12 @@ 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 = 1;
if (!schedule_hrtimeout(timeout, HRTIMER_MODE_ABS))
ret = -ETIME;
- current->in_iowait = io_wait;
+ current->in_iowait = 0;
return ret;
}

--
2.43.0