netdev - [PATCH 1/1] vhost: Provide a kernel warning if mutex is held whilst clean-up in progress

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Date:   Thu,  3 Mar 2022 15:19:29 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     lee.jones@...aro.org, mst@...hat.com, jasowang@...hat.com
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Subject: [PATCH 1/1] vhost: Provide a kernel warning if mutex is held whilst clean-up in progress

All workers/users should be halted before any clean-up should take place.

Suggested-by:  Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
---
 drivers/vhost/vhost.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index bbaff6a5e21b8..d935d2506963f 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -693,6 +693,9 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
 	int i;
 
 	for (i = 0; i < dev->nvqs; ++i) {
+		/* Ideally all workers should be stopped prior to clean-up */
+		WARN_ON(mutex_is_locked(&dev->vqs[i]->mutex));
+
 		mutex_lock(&dev->vqs[i]->mutex);
 		if (dev->vqs[i]->error_ctx)
 			eventfd_ctx_put(dev->vqs[i]->error_ctx);
-- 
2.35.1.574.g5d30c73bfb-goog