[PATCH 3.10 157/268] sd: get disk reference in sd_check_events()

Willy Tarreau
2017-06-19T18:38:08Z

From: Hannes Reinecke <hare@suse.de>

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: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
drivers/scsi/sd.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 749893e..880a300 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1354,11 +1354,15 @@ 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"));

/*
@@ -1415,6 +1419,7 @@ out:
kfree(sshdr);
retval = sdp->changed ? DISK_EVENT_MEDIA_CHANGE : 0;
sdp->changed = 0;
+ scsi_disk_put(sdkp);
return retval;
}

--
2.8.0.rc2.1.gbe9624a