linux-kernel - [PATCH 3.16 018/305] scsi: Add intermediate STARGET_REMOVE state to scsi_target

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Message-ID: <lsq.1471110171.631415838@decadent.org.uk>
Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Hannes Reinecke" <hare@...e.com>,
	"Ewan D. Milne" <emilne@...hat.com>,
	"Sergey Senozhatsky" <sergey.senozhatsky@...il.com>,
	"Johannes Thumshirn" <jthumshirn@...e.de>,
	"James Bottomley" <jejb@...ux.vnet.ibm.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>
Subject: [PATCH 3.16 018/305] scsi: Add intermediate STARGET_REMOVE state
 to scsi_target_state

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Thumshirn <jthumshirn@...e.de>

commit f05795d3d771f30a7bdc3a138bf714b06d42aa95 upstream.

Add intermediate STARGET_REMOVE state to scsi_target_state to avoid
running into the BUG_ON() in scsi_target_reap(). The STARGET_REMOVE
state is only valid in the path from scsi_remove_target() to
scsi_target_destroy() indicating this target is going to be removed.

This re-fixes the problem introduced in commits bc3f02a795d3 ("[SCSI]
scsi_remove_target: fix softlockup regression on hot remove") and
40998193560d ("scsi: restart list search after unlock in
scsi_remove_target") in a more comprehensive way.

[mkp: Included James' fix for scsi_target_destroy()]

Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
Fixes: 40998193560dab6c3ce8d25f4fa58a23e252ef38
Reported-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Reviewed-by: Ewan D. Milne <emilne@...hat.com>
Reviewed-by: Hannes Reinecke <hare@...e.com>
Reviewed-by: James Bottomley <jejb@...ux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/scsi/scsi_scan.c   | 1 +
 drivers/scsi/scsi_sysfs.c  | 2 ++
 include/scsi/scsi_device.h | 1 +
 3 files changed, 4 insertions(+)

--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -320,6 +320,7 @@ static void scsi_target_destroy(struct s
 	struct Scsi_Host *shost = dev_to_shost(dev->parent);
 	unsigned long flags;
 
+	BUG_ON(starget->state == STARGET_DEL);
 	starget->state = STARGET_DEL;
 	transport_destroy_device(dev);
 	spin_lock_irqsave(shost->host_lock, flags);
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1155,11 +1155,13 @@ restart:
 	spin_lock_irqsave(shost->host_lock, flags);
 	list_for_each_entry(starget, &shost->__targets, siblings) {
 		if (starget->state == STARGET_DEL ||
+		    starget->state == STARGET_REMOVE ||
 		    starget == last_target)
 			continue;
 		if (starget->dev.parent == dev || &starget->dev == dev) {
 			kref_get(&starget->reap_ref);
 			last_target = starget;
+			starget->state = STARGET_REMOVE;
 			spin_unlock_irqrestore(shost->host_lock, flags);
 			__scsi_remove_target(starget);
 			scsi_target_reap(starget);
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -264,6 +264,7 @@ struct scsi_dh_data {
 enum scsi_target_state {
 	STARGET_CREATED = 1,
 	STARGET_RUNNING,
+	STARGET_REMOVE,
 	STARGET_DEL,
 };