linux-kernel - [PATCH v2 3/3] vhost: Fix livepatch timeouts in vhost

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Message-Id: <f263a0feb85b1f52ad23d33c58943604c939ebb4.1676672328.git.jpoimboe@kernel.org>
Date:   Fri, 17 Feb 2023 14:22:56 -0800
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     live-patching@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Seth Forshee <sforshee@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Song Liu <song@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Miroslav Benes <mbenes@...e.cz>,
        Jiri Kosina <jikos@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Rik van Riel <riel@...riel.com>
Subject: [PATCH v2 3/3] vhost: Fix livepatch timeouts in vhost_worker()

Livepatch timeouts were reported due to busy vhost_worker() kthreads.
Now that cond_resched() can do livepatch task switching, use
cond_resched() in vhost_worker().  That's the better way to
conditionally call schedule() anyway.

Reported-by: Seth Forshee (DigitalOcean) <sforshee@...nel.org>
Link: https://lkml.kernel.org/lkml/20230120-vhost-klp-switching-v1-0-7c2b65519c43@kernel.org
Tested-by: Seth Forshee (DigitalOcean) <sforshee@...nel.org>
Reviewed-by: Petr Mladek <pmladek@...e.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 drivers/vhost/vhost.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 43c9770b86e5..87e3cf12da1c 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -363,8 +363,7 @@ static int vhost_worker(void *data)
 			kcov_remote_start_common(dev->kcov_handle);
 			work->fn(work);
 			kcov_remote_stop();
-			if (need_resched())
-				schedule();
+			cond_resched();
 		}
 	}
 	kthread_unuse_mm(dev->mm);
-- 
2.39.1