[PATCH v1 3/5] pipe: Add TASK_FREEZABLE to read and open sleeps

[Dai Junbing]

When a process sleeps during read on pipes or open on FIFOs,
add the TASK_FREEZABLE flag. This prevents premature wakeups during
system suspend/resume operations, avoiding unnecessary wakeup overhead.

In both the pipe read and FIFO open paths, no kernel locks are held
during sleep. Therefore, adding TASK_FREEZABLE is safe.

Signed-off-by: Dai Junbing <daijunbing@xxxxxxxx>
---
 fs/pipe.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/pipe.c b/fs/pipe.c
index 45077c37bad1..b49e382c59ba 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -385,7 +385,7 @@ anon_pipe_read(struct kiocb *iocb, struct iov_iter *to)
 		 * since we've done any required wakeups and there's no need
 		 * to mark anything accessed. And we've dropped the lock.
 		 */
-		if (wait_event_interruptible_exclusive(pipe->rd_wait, pipe_readable(pipe)) < 0)
+		if (wait_event_freezable_exclusive(pipe->rd_wait, pipe_readable(pipe)) < 0)
 			return -ERESTARTSYS;
 
 		wake_next_reader = true;
@@ -1098,7 +1098,7 @@ static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt)
 	int cur = *cnt;
 
 	while (cur == *cnt) {
-		prepare_to_wait(&pipe->rd_wait, &rdwait, TASK_INTERRUPTIBLE);
+		prepare_to_wait(&pipe->rd_wait, &rdwait, TASK_INTERRUPTIBLE | TASK_FREEZABLE);
 		pipe_unlock(pipe);
 		schedule();
 		finish_wait(&pipe->rd_wait, &rdwait);
-- 
2.25.1