On Tue, Oct 05, 2021 at 03:04:07AM -0400, Michael S. Tsirkin wrote: > 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.
That's a pathological case that is not "in the field" except by people who want to abuse the system as root. And they can do much worse things than that. > Fixing this comprehensively needs some thought, and new APIs. > Let's at least handle the specific case of virtio_console > removal that was reported in the field. Let's fix this correctly, don't just hack it up now. > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1786239 > Signed-off-by: Michael S. Tsirkin <[email protected]> > --- > drivers/char/virtio_console.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > index 7eaf303a7a86..c852ce0b4d56 100644 > --- a/drivers/char/virtio_console.c > +++ b/drivers/char/virtio_console.c > @@ -1956,6 +1956,12 @@ 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 */ newline before comment? thanks, greg k-h _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
