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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Sasha Levin <sashal@kernel.org>,
	gregkh@linuxfoundation.org, amit@kernel.org,
	virtualization@lists.linux-foundation.org,
	"Michael S. Tsirkin" <mst@redhat.com>
Subject: [PATCH AUTOSEL 4.9 1/2] virtio_console: break out of buf poll on remove
Date: Wed, 16 Mar 2022 10:19:07 -0400	[thread overview]
Message-ID: <20220316141908.248848-1-sashal@kernel.org> (raw)

From: "Michael S. Tsirkin" <mst@redhat.com>

[ Upstream commit 0e7174b9d5877130fec41fb4a16e0c2ee4958d44 ]

A common pattern for device reset is currently:
vdev->config->reset(vdev);
.. cleanup ..

reset prevents new interrupts from arriving and waits for interrupt
handlers to finish.

However if - as is common - the handler queues a work request which is
flushed during the cleanup stage, we have code adding buffers / trying
to get buffers while device is reset. Not good.

This was reproduced by running
	modprobe virtio_console
	modprobe -r virtio_console
in a loop.

Fix this up by calling virtio_break_device + flush before reset.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1786239
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/char/virtio_console.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 2632b0fdb1b5..a6b6dc204c1f 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -2004,6 +2004,13 @@ static void virtcons_remove(struct virtio_device *vdev)
 	list_del(&portdev->list);
 	spin_unlock_irq(&pdrvdata_lock);
 
+	/* Device is going away, exit any polling for buffers */
+	virtio_break_device(vdev);
+	if (use_multiport(portdev))
+		flush_work(&portdev->control_work);
+	else
+		flush_work(&portdev->config_work);
+
 	/* Disable interrupts for vqs */
 	vdev->config->reset(vdev);
 	/* Finish up work that's lined up */
-- 
2.34.1

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Virtualization@lists.linux-foundation.org
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WARNING: multiple messages have this Message-ID (diff)
From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	Sasha Levin <sashal@kernel.org>,
	amit@kernel.org, gregkh@linuxfoundation.org,
	virtualization@lists.linux-foundation.org
Subject: [PATCH AUTOSEL 4.9 1/2] virtio_console: break out of buf poll on remove
Date: Wed, 16 Mar 2022 10:19:07 -0400	[thread overview]
Message-ID: <20220316141908.248848-1-sashal@kernel.org> (raw)

From: "Michael S. Tsirkin" <mst@redhat.com>

[ Upstream commit 0e7174b9d5877130fec41fb4a16e0c2ee4958d44 ]

A common pattern for device reset is currently:
vdev->config->reset(vdev);
.. cleanup ..

reset prevents new interrupts from arriving and waits for interrupt
handlers to finish.

However if - as is common - the handler queues a work request which is
flushed during the cleanup stage, we have code adding buffers / trying
to get buffers while device is reset. Not good.

This was reproduced by running
	modprobe virtio_console
	modprobe -r virtio_console
in a loop.

Fix this up by calling virtio_break_device + flush before reset.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1786239
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/char/virtio_console.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 2632b0fdb1b5..a6b6dc204c1f 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -2004,6 +2004,13 @@ static void virtcons_remove(struct virtio_device *vdev)
 	list_del(&portdev->list);
 	spin_unlock_irq(&pdrvdata_lock);
 
+	/* Device is going away, exit any polling for buffers */
+	virtio_break_device(vdev);
+	if (use_multiport(portdev))
+		flush_work(&portdev->control_work);
+	else
+		flush_work(&portdev->config_work);
+
 	/* Disable interrupts for vqs */
 	vdev->config->reset(vdev);
 	/* Finish up work that's lined up */
-- 
2.34.1


             reply	other threads:[~2022-03-16 14:19 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-16 14:19 Sasha Levin [this message]
2022-03-16 14:19 ` [PATCH AUTOSEL 4.9 1/2] virtio_console: break out of buf poll on remove Sasha Levin
2022-03-16 14:19 ` [PATCH AUTOSEL 4.9 2/2] ethernet: sun: Free the coherent when failing in probing Sasha Levin

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