From afed6271f5b0d78ca1a3739c1da4aa3629b26bba Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 7 Mar 2023 17:56:28 -0700 Subject: [PATCH] pipe: set FMODE_NOWAIT on pipes Pipes themselves do not hold the the pipe lock across IO, and hence are safe for RWF_NOWAIT/IOCB_NOWAIT usage. The "contract" for NOWAIT is really "should not do IO under this lock", not strictly that we cannot block or that the below code is in any way atomic. Pipes fulfil that criteria. Acked-by: Dave Chinner Reviewed-by: Christian Brauner Signed-off-by: Jens Axboe --- fs/pipe.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/pipe.c b/fs/pipe.c index 42c7ff4..ceb17d2 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -976,6 +976,9 @@ static int __do_pipe_flags(int *fd, struct file **files, int flags) audit_fd_pair(fdr, fdw); fd[0] = fdr; fd[1] = fdw; + /* pipe groks IOCB_NOWAIT */ + files[0]->f_mode |= FMODE_NOWAIT; + files[1]->f_mode |= FMODE_NOWAIT; return 0; err_fdr: -- 2.7.4