[PATCH 05/31] Make __scsi_remove_device go straight from BLOCKED to DEL

Bart Van Assche
2017-05-24T00:33:54Z

If a device is blocked, make __scsi_remove_device() cause it to
transition to the DEL state. This means that all the commands
issued in .shutdown() will error in the mid-layer, thus making
the removal proceed without being stopped.

This patch is a slightly modified version of a patch from James
Bottomley. This patch avoids that the following lockup occurs:

Call Trace:
schedule+0x35/0x80
schedule_timeout+0x237/0x2d0
io_schedule_timeout+0xa6/0x110
wait_for_completion_io+0xa3/0x110
blk_execute_rq+0xdf/0x120
scsi_execute+0xce/0x150 [scsi_mod]
scsi_execute_req_flags+0x8f/0xf0 [scsi_mod]
sd_sync_cache+0xa9/0x190 [sd_mod]
sd_shutdown+0x6a/0x100 [sd_mod]
sd_remove+0x64/0xc0 [sd_mod]
__device_release_driver+0x8d/0x120
device_release_driver+0x1e/0x30
bus_remove_device+0xf9/0x170
device_del+0x127/0x240
__scsi_remove_device+0xc1/0xd0 [scsi_mod]
scsi_forget_host+0x57/0x60 [scsi_mod]
scsi_remove_host+0x72/0x110 [scsi_mod]
srp_remove_work+0x8b/0x200 [ib_srp]

Reported-by: Israel Rukshin <israelr@mellanox.com>
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Israel Rukshin <israelr@mellanox.com>
Cc: Max Gurtovoy <maxg@mellanox.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Benjamin Block <bblock@linux.vnet.ibm.com>
---
drivers/scsi/scsi_lib.c | 2 +-
drivers/scsi/scsi_sysfs.c | 13 +++++++++++++
2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 0ee5c2133e4c..5c6874cf4388 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2613,7 +2613,6 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
case SDEV_QUIESCE:
case SDEV_OFFLINE:
case SDEV_TRANSPORT_OFFLINE:
- case SDEV_BLOCK:
break;
default:
goto illegal;
@@ -2627,6 +2626,7 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
case SDEV_OFFLINE:
case SDEV_TRANSPORT_OFFLINE:
case SDEV_CANCEL:
+ case SDEV_BLOCK:
case SDEV_CREATED_BLOCK:
break;
default:
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index a91537a3abbf..1f243ac16010 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1290,7 +1290,20 @@ void __scsi_remove_device(struct scsi_device *sdev)
* wait until it has finished before changing the device state.
*/
mutex_lock(&sdev->state_mutex);
+ /*
+ * If blocked, we go straight to DEL and restart the queue so
+ * any commands issued during driver shutdown (like sync
+ * cache) are errored immediately.
+ */
res = scsi_device_set_state(sdev, SDEV_CANCEL);
+ if (res != 0) {
+ res = scsi_device_set_state(sdev, SDEV_DEL);
+ if (res == 0) {
+ scsi_start_queue(sdev);
+ sdev_printk(KERN_DEBUG, sdev,
+ "Changed state from BLOCKED to DEL\n");
+ }
+ }
mutex_unlock(&sdev->state_mutex);

if (res != 0)
--
2.12.2