Re: [dm-devel] dm-mq and end_clone_request()

[Bart Van Assche <bart.vanassche@sandisk.com>]

On 08/08/2016 08:26 AM, Laurence Oberman wrote:
> I will test this as well.
> I have lost my DDN array today (sadly:)) but I have two systems
> back to back again using ramdisk on the one to serve LUNS.
> 
> If I pull from  https://github.com/bvanassche/linux again, and
> switch branch to srp-initiator-for-next, will I get all Mikes
> latest patches from last week + this. I guess I can just check
> myself, but might as well just ask.

Hello Laurence,

Sorry but I do not yet have a fix available for the scsi_forget_host()
crash you reported in an earlier e-mail. But Mike's latest patches
including the patch below are now available at
https://github.com/bvanassche/linux in the srp-initiator-for-next
branch. Further feedback is welcome.

Thanks,

Bart.

[PATCH] Check invariants at runtime

Warn if sdev->sdev_state != SDEV_DEL when __scsi_remove_device()
returns. Check whether all __scsi_remove_device() callers hold the
scan_mutex.
---
 drivers/scsi/scsi_sysfs.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 82209ad4..a21e321 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1312,6 +1312,8 @@ void __scsi_remove_device(struct scsi_device *sdev)
 {
 	struct device *dev = &sdev->sdev_gendev, *sdp = NULL;
 
+	lockdep_assert_held(&sdev->host->scan_mutex);
+
 	/*
 	 * This cleanup path is not reentrant and while it is impossible
 	 * to get a new reference with scsi_device_get() someone can still
@@ -1321,8 +1323,11 @@ void __scsi_remove_device(struct scsi_device *sdev)
 		return;
 
 	if (sdev->is_visible) {
-		if (scsi_device_set_state(sdev, SDEV_CANCEL) != 0)
+		if (scsi_device_set_state(sdev, SDEV_CANCEL) != 0) {
+			WARN_ONCE(sdev->sdev_state != SDEV_DEL,
+				  "sdev state %d\n", sdev->sdev_state);
 			return;
+		}
 
 		bsg_unregister_queue(sdev->request_queue);
 		sdp = scsi_get_ulpdev(dev);
@@ -1339,6 +1344,8 @@ void __scsi_remove_device(struct scsi_device *sdev)
 	 * device.
 	 */
 	scsi_device_set_state(sdev, SDEV_DEL);
+	WARN_ONCE(sdev->sdev_state != SDEV_DEL, "sdev state %d\n",
+		  sdev->sdev_state);
 	blk_cleanup_queue(sdev->request_queue);
 	cancel_work_sync(&sdev->requeue_work);
 
-- 
2.9.2