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From: Jens Axboe <axboe@kernel.dk>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [PATCH] pipe: read/write_iter() handler should check for IOCB_NOWAIT
Date: Thu, 30 Apr 2020 10:24:46 -0600	[thread overview]
Message-ID: <273d8294-2508-a4c2-f96e-a6a394f94166@kernel.dk> (raw)

Pipe read/write only checks for the file O_NONBLOCK flag, but we should
also check for IOCB_NOWAIT for whether or not we should handle this read
or write in a non-blocking fashion. If we don't, then we will block on
data or space for iocbs that explicitly asked for non-blocking
operation. This messes up callers that explicitly ask for non-blocking
operations.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/fs/pipe.c b/fs/pipe.c
index 16fb72e9abf7..5711e6bca12d 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -363,7 +363,8 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to)
 			break;
 		if (ret)
 			break;
-		if (filp->f_flags & O_NONBLOCK) {
+		if ((filp->f_flags & O_NONBLOCK) ||
+		    (iocb->ki_flags & IOCB_NOWAIT)) {
 			ret = -EAGAIN;
 			break;
 		}
@@ -566,7 +567,8 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
 			continue;
 
 		/* Wait for buffer space to become available. */
-		if (filp->f_flags & O_NONBLOCK) {
+		if ((filp->f_flags & O_NONBLOCK) ||
+		    (iocb->ki_flags & IOCB_NOWAIT)) {
 			if (!ret)
 				ret = -EAGAIN;
 			break;

-- 
Jens Axboe


             reply	other threads:[~2020-04-30 16:24 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-30 16:24 Jens Axboe [this message]
2020-04-30 17:58 ` [PATCH] pipe: read/write_iter() handler should check for IOCB_NOWAIT Matthew Wilcox
2020-04-30 18:47   ` Jens Axboe
2020-04-30 19:51     ` Jens Axboe
2020-04-30 19:56       ` Jens Axboe
2020-05-01  3:58 ` Al Viro
2020-05-01  4:14   ` Jens Axboe
2020-05-01  4:21     ` Jens Axboe

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