linux-kernel - [PATCH net-next v3 4/7] eventpoll: Trigger napi_busy_loop, if prefer_busy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20241101004846.32532-5-jdamato@fastly.com>
Date: Fri,  1 Nov 2024 00:48:31 +0000
From: Joe Damato <jdamato@...tly.com>
To: netdev@...r.kernel.org
Cc: pabeni@...hat.com,
	namangulati@...gle.com,
	edumazet@...gle.com,
	amritha.nambiar@...el.com,
	sridhar.samudrala@...el.com,
	sdf@...ichev.me,
	peter@...eblog.net,
	m2shafiei@...terloo.ca,
	bjorn@...osinc.com,
	hch@...radead.org,
	willy@...radead.org,
	willemdebruijn.kernel@...il.com,
	skhawaja@...gle.com,
	kuba@...nel.org,
	Martin Karsten <mkarsten@...terloo.ca>,
	Joe Damato <jdamato@...tly.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	Jan Kara <jack@...e.cz>,
	linux-fsdevel@...r.kernel.org (open list:FILESYSTEMS (VFS and infrastructure)),
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH net-next v3 4/7] eventpoll: Trigger napi_busy_loop, if prefer_busy_poll is set

From: Martin Karsten <mkarsten@...terloo.ca>

Setting prefer_busy_poll now leads to an effectively nonblocking
iteration though napi_busy_loop, even when busy_poll_usecs is 0.

Signed-off-by: Martin Karsten <mkarsten@...terloo.ca>
Co-developed-by: Joe Damato <jdamato@...tly.com>
Signed-off-by: Joe Damato <jdamato@...tly.com>
Tested-by: Joe Damato <jdamato@...tly.com>
Tested-by: Martin Karsten <mkarsten@...terloo.ca>
Acked-by: Stanislav Fomichev <sdf@...ichev.me>
---
 v1 -> v2:
   - Rebased to apply now that commit b9ca079dd6b0 ("eventpoll: Annotate
     data-race of busy_poll_usecs") has been picked up from VFS.

 fs/eventpoll.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 1ae4542f0bd8..f9e0d9307dad 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -420,7 +420,9 @@ static bool busy_loop_ep_timeout(unsigned long start_time,
 
 static bool ep_busy_loop_on(struct eventpoll *ep)
 {
-	return !!READ_ONCE(ep->busy_poll_usecs) || net_busy_loop_on();
+	return !!READ_ONCE(ep->busy_poll_usecs) ||
+	       READ_ONCE(ep->prefer_busy_poll) ||
+	       net_busy_loop_on();
 }
 
 static bool ep_busy_loop_end(void *p, unsigned long start_time)
-- 
2.25.1