sd: get disk reference in sd_check_events()

commit eb72d0bb84eee5d0dc3044fd17b75e7101dabb57 upstream.

sd_check_events() is called asynchronously, and might race
with device removal. So always take a disk reference when
processing the event to avoid the device being removed while
the event is processed.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Jinpu Wang <jinpu.wang@profitbricks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 6ee5074..78430ef 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1398,11 +1398,15 @@ static int media_not_present(struct scsi_disk *sdkp,
  **/
 static unsigned int sd_check_events(struct gendisk *disk, unsigned int clearing)
 {
-       struct scsi_disk *sdkp = scsi_disk(disk);
-       struct scsi_device *sdp = sdkp->device;
+       struct scsi_disk *sdkp = scsi_disk_get(disk);
+       struct scsi_device *sdp;
        struct scsi_sense_hdr *sshdr = NULL;
        int retval;
 
+       if (!sdkp)
+               return 0;
+
+       sdp = sdkp->device;
        SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_check_events\n"));
 
        /*
@@ -1459,6 +1463,7 @@ out:
        kfree(sshdr);
        retval = sdp->changed ? DISK_EVENT_MEDIA_CHANGE : 0;
        sdp->changed = 0;
+       scsi_disk_put(sdkp);
        return retval;
 }