[PATCH v4 22/25] virtio_scsi: fix race on device removal
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2014-10-13 07:49:59
Also in:
kvm, linux-s390, linux-scsi, lkml, netdev
Subsystem:
scsi subsystem, the rest, virtio block and scsi drivers · Maintainers:
"James E.J. Bottomley", "Martin K. Petersen", Linus Torvalds, "Michael S. Tsirkin", Jason Wang
We cancel event work on device removal, but an interrupt could trigger immediately after this, and queue it again. To fix, set a flag. Loosely based on patch by Paolo Bonzini Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- drivers/scsi/virtio_scsi.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 501838d..327eba0 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c@@ -110,6 +110,9 @@ struct virtio_scsi { /* CPU hotplug notifier */ struct notifier_block nb; + /* Protected by event_vq lock */ + bool stop_events; + struct virtio_scsi_vq ctrl_vq; struct virtio_scsi_vq event_vq; struct virtio_scsi_vq req_vqs[];
@@ -303,6 +306,11 @@ static void virtscsi_cancel_event_work(struct virtio_scsi *vscsi) { int i; + /* Stop scheduling work before calling cancel_work_sync. */ + spin_lock_irq(&vscsi->event_vq.vq_lock); + vscsi->stop_events = true; + spin_unlock_irq(&vscsi->event_vq.vq_lock); + for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++) cancel_work_sync(&vscsi->event_list[i].work); }
@@ -390,7 +398,8 @@ static void virtscsi_complete_event(struct virtio_scsi *vscsi, void *buf) { struct virtio_scsi_event_node *event_node = buf; - queue_work(system_freezable_wq, &event_node->work); + if (!vscsi->stop_events) + queue_work(system_freezable_wq, &event_node->work); } static void virtscsi_event_done(struct virtqueue *vq)
--
MST