linux-kernel - [PATCH AUTOSEL 4.14 125/170] drbd: skip spurious timeout (ping-timeo) when failing promote

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: <20190128161200.55107-125-sashal@kernel.org>
Date:   Mon, 28 Jan 2019 11:11:15 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Lars Ellenberg <lars.ellenberg@...bit.com>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>,
        drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 125/170] drbd: skip spurious timeout (ping-timeo) when failing promote

From: Lars Ellenberg <lars.ellenberg@...bit.com>

[ Upstream commit 9848b6ddd8c92305252f94592c5e278574e7a6ac ]

If you try to promote a Secondary while connected to a Primary
and allow-two-primaries is NOT set, we will wait for "ping-timeout"
to give this node a chance to detect a dead primary,
in case the cluster manager noticed faster than we did.

But if we then are *still* connected to a Primary,
we fail (after an additional timeout of ping-timout).

This change skips the spurious second timeout.

Most people won't notice really,
since "ping-timeout" by default is half a second.

But in some installations, ping-timeout may be 10 or 20 seconds or more,
and spuriously delaying the error return becomes annoying.

Signed-off-by: Lars Ellenberg <lars.ellenberg@...bit.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/block/drbd/drbd_nl.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index a12f77e6891e..ad13ec66c8e4 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -668,14 +668,15 @@ drbd_set_role(struct drbd_device *const device, enum drbd_role new_role, int for
 		if (rv == SS_TWO_PRIMARIES) {
 			/* Maybe the peer is detected as dead very soon...
 			   retry at most once more in this case. */
-			int timeo;
-			rcu_read_lock();
-			nc = rcu_dereference(connection->net_conf);
-			timeo = nc ? (nc->ping_timeo + 1) * HZ / 10 : 1;
-			rcu_read_unlock();
-			schedule_timeout_interruptible(timeo);
-			if (try < max_tries)
+			if (try < max_tries) {
+				int timeo;
 				try = max_tries - 1;
+				rcu_read_lock();
+				nc = rcu_dereference(connection->net_conf);
+				timeo = nc ? (nc->ping_timeo + 1) * HZ / 10 : 1;
+				rcu_read_unlock();
+				schedule_timeout_interruptible(timeo);
+			}
 			continue;
 		}
 		if (rv < SS_SUCCESS) {
-- 
2.19.1