Revert "scsi: make 'state' device attribute pollable"

This reverts commit 8a97712.

This commit added a call to sysfs_notify() from within
scsi_device_set_state(), which in turn turns out to make libata very
unhappy, because ata_eh_detach_dev() does

        spin_lock_irqsave(ap->lock, flags);
        ..
        if (ata_scsi_offline_dev(dev)) {
                dev->flags |= ATA_DFLAG_DETACHED;
                ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
        }

and ata_scsi_offline_dev() then does that scsi_device_set_state() to set
it offline.

So now we called sysfs_notify() from within a spinlocked region, which
really doesn't work.  The 0day robot reported this as:

   BUG: sleeping function called from invalid context at kernel/locking/mutex.c:238

because sysfs_notify() ends up calling kernfs_find_and_get_ns() which
then does mutex_lock(&kernfs_mutex)..

The pollability of the device state isn't critical, so revert this all
for now, and maybe we'll do it differently in the future.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/scsi/scsi_lib.c

@@ -2685,7 +2685,6 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
 
 	}
 	sdev->sdev_state = state;
-	sysfs_notify(&sdev->sdev_gendev.kobj, NULL, "state");
 	return 0;
 
  illegal:
@@ -3109,15 +3108,13 @@ int scsi_internal_device_unblock_nowait(struct scsi_device *sdev,
 	case SDEV_BLOCK:
 	case SDEV_TRANSPORT_OFFLINE:
 		sdev->sdev_state = new_state;
-		sysfs_notify(&sdev->sdev_gendev.kobj, NULL, "state");
 		break;
 	case SDEV_CREATED_BLOCK:
 		if (new_state == SDEV_TRANSPORT_OFFLINE ||
 		    new_state == SDEV_OFFLINE)
 			sdev->sdev_state = new_state;
 		else
 			sdev->sdev_state = SDEV_CREATED;
-		sysfs_notify(&sdev->sdev_gendev.kobj, NULL, "state");
 		break;
 	case SDEV_CANCEL:
 	case SDEV_OFFLINE:

drivers/scsi/scsi_transport_srp.c

@@ -556,11 +556,8 @@ int srp_reconnect_rport(struct srp_rport *rport)
 		 */
 		shost_for_each_device(sdev, shost) {
 			mutex_lock(&sdev->state_mutex);
-			if (sdev->sdev_state == SDEV_OFFLINE) {
+			if (sdev->sdev_state == SDEV_OFFLINE)
 				sdev->sdev_state = SDEV_RUNNING;
-				sysfs_notify(&sdev->sdev_gendev.kobj,
-					     NULL, "state");
-			}
 			mutex_unlock(&sdev->state_mutex);
 		}
 	} else if (rport->state == SRP_RPORT_RUNNING) {