linux-kernel - [PATCH v2 2/4] kernel/watch_queue: Use pipe

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Message-ID: <20250307052919.34542-3-kprateek.nayak@amd.com>
Date: Fri, 7 Mar 2025 05:29:17 +0000
From: K Prateek Nayak <kprateek.nayak@....com>
To: Linus Torvalds <torvalds@...ux-foundation.org>, Oleg Nesterov
	<oleg@...hat.com>, Alexander Viro <viro@...iv.linux.org.uk>, "Christian
 Brauner" <brauner@...nel.org>, <linux-fsdevel@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: Jan Kara <jack@...e.cz>, "Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Mateusz Guzik <mjguzik@...il.com>, Rasmus Villemoes <ravi@...vas.dk>,
	"Gautham R. Shenoy" <gautham.shenoy@....com>, <Neeraj.Upadhyay@....com>,
	<Ananth.narayan@....com>, Swapnil Sapkal <swapnil.sapkal@....com>, "K Prateek
 Nayak" <kprateek.nayak@....com>
Subject: [PATCH v2 2/4] kernel/watch_queue: Use pipe_buf() to retrieve the pipe buffer

Use pipe_buf() helper to retrieve the pipe buffer in
post_one_notification() replacing the open-coded the logic.

Suggested-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@....com>
---
Changelog:

RFC v1..v2:

o New patch.
---
 kernel/watch_queue.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
index 5267adeaa403..605129eb61a1 100644
--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -101,12 +101,11 @@ static bool post_one_notification(struct watch_queue *wqueue,
 	struct pipe_inode_info *pipe = wqueue->pipe;
 	struct pipe_buffer *buf;
 	struct page *page;
-	unsigned int head, tail, mask, note, offset, len;
+	unsigned int head, tail, note, offset, len;
 	bool done = false;
 
 	spin_lock_irq(&pipe->rd_wait.lock);
 
-	mask = pipe->ring_size - 1;
 	head = pipe->head;
 	tail = pipe->tail;
 	if (pipe_full(head, tail, pipe->ring_size))
@@ -124,7 +123,7 @@ static bool post_one_notification(struct watch_queue *wqueue,
 	memcpy(p + offset, n, len);
 	kunmap_atomic(p);
 
-	buf = &pipe->bufs[head & mask];
+	buf = pipe_buf(pipe, head);
 	buf->page = page;
 	buf->private = (unsigned long)wqueue;
 	buf->ops = &watch_queue_pipe_buf_ops;
@@ -147,7 +146,7 @@ static bool post_one_notification(struct watch_queue *wqueue,
 	return done;
 
 lost:
-	buf = &pipe->bufs[(head - 1) & mask];
+	buf = pipe_buf(pipe, head - 1);
 	buf->flags |= PIPE_BUF_FLAG_LOSS;
 	goto out;
 }
-- 
2.43.0