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Tsirkin" To: linux-kernel@vger.kernel.org Cc: Amit Shah , Arnd Bergmann , Greg Kroah-Hartman , virtualization@lists.linux-foundation.org Subject: [PATCH v2 2/3] virtio_console: break out of buf poll on remove Message-ID: <20220114215641.239984-3-mst@redhat.com> References: <20220114215641.239984-1-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220114215641.239984-1-mst@redhat.com> X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 2359889a35a0..e3c430539a17 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -1957,6 +1957,13 @@ 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 */ virtio_reset_device(vdev); /* Finish up work that's lined up */ -- MST