The last step of virtscsi_handle_event is to call virtscsi_kick_event, which calls INIT_WORK on it's own work item. INIT_WORK resets the work item's data bits to 0.
If this occurs while the work item is being flushed by cancel_work_sync, then kernel/workqueue.c/work_offqd_enable triggers a kernel warning, as it expects the "disable" bit to be 1: [ 21.450115] workqueue: work disable count underflowed [ 21.450117] WARNING: CPU: 1 PID: 56 at kernel/workqueue.c:4328 enable_work+0x10a/0x120 ... [ 21.450171] Call Trace: [ 21.450173] [<000003db2e5bdc3e>] enable_work+0x10e/0x120 [ 21.450176] ([<000003db2e5bdc3a>] enable_work+0x10a/0x120) [ 21.450178] [<000003db2e5bdd86>] cancel_work_sync+0x86/0xa0 [ 21.450181] [<000003daae97d9e4>] virtscsi_remove+0xb4/0xd0 [virtio_scsi] [ 21.450184] [<000003db2ef3b5ca>] virtio_dev_remove+0x6a/0xd0 [ 21.450186] [<000003db2ef9106c>] device_release_driver_internal+0x1ac/0x260 [ 21.450190] [<000003db2ef8edc8>] bus_remove_device+0xf8/0x190 [ 21.450192] [<000003db2ef88d72>] device_del+0x142/0x340 [ 21.450194] [<000003db2ef88fa0>] device_unregister+0x30/0xa0 [ 21.450196] [<000003db2ef3b2fa>] unregister_virtio_device+0x2a/0x40 This warning may occur if a controller is detached immediately following a disk detach. Move the INIT_WORK call to prevent this. Don't re-init event list work items in virtscsi_kick_event, init them only once in virtscsi_init instead. Signed-off-by: Joshua Daley <[email protected]> --- drivers/scsi/virtio_scsi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 6efbeaa30f65..fe1bf37f1317 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -240,7 +240,6 @@ static int virtscsi_kick_event(struct virtio_scsi *vscsi, struct scatterlist sg; unsigned long flags; - INIT_WORK(&event_node->work, virtscsi_handle_event); sg_init_one(&sg, event_node->event, sizeof(struct virtio_scsi_event)); spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags); @@ -896,6 +895,9 @@ static int virtscsi_init(struct virtio_device *vdev, virtscsi_config_set(vdev, cdb_size, VIRTIO_SCSI_CDB_SIZE); virtscsi_config_set(vdev, sense_size, VIRTIO_SCSI_SENSE_SIZE); + for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++) + INIT_WORK(&vscsi->event_list[i].work, virtscsi_handle_event); + err = 0; out: -- 2.34.1
