linux-kernel - [RESEND PATCH v2 2/2] scsi: Add intermediate STARGET_REMOVE state to scsi_target

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Date:	Wed, 30 Mar 2016 09:09:53 +0200
From:	Johannes Thumshirn <jthumshirn@...e.de>
To:	"Martin K. Petersen" <martin.petersen@...cle.com>,
	"James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>
Cc:	"Ewan D. Milne" <emilne@...hat.com>,
	Hannes Reinecke <hare@...e.de>,
	Christoph Hellwig <hch@...radead.org>,
	Johannes Thumshirn <jthumshirn@...e.de>,
	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: [RESEND PATCH v2 2/2] scsi: Add intermediate STARGET_REMOVE state to scsi_target_state

Add intermediate STARGET_REMOVE state to scsi_target_state to avoid running
into the BUG_ON() in scsi_target_reap().

This intermediate state is only valid in the path from scsi_remove_target() to
scsi_target_destroy() indicating this target is going to be removed.

Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
Fixes: 40998193560dab6c3ce8d25f4fa58a23e252ef38
Cc: stable@...r.kernel.org
Reviewed-by: Hannes Reinecke <hare@...e.com>
Reviewed-by: Ewan D. Milne <emilne@...hat.com>
---

Changes from v1:
* The state transition from STARGET_CREATED to STARGET_DEL is legitimate,
  so don't BUG() on it. Found by the 0-Day Bot.


 drivers/scsi/scsi_scan.c   | 2 ++
 drivers/scsi/scsi_sysfs.c  | 4 +++-
 include/scsi/scsi_device.h | 1 +
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 6a82066..63b8bca 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -315,6 +315,8 @@ static void scsi_target_destroy(struct scsi_target *starget)
 	struct Scsi_Host *shost = dev_to_shost(dev->parent);
 	unsigned long flags;
 
+	BUG_ON(starget->state != STARGET_REMOVE &&
+	       starget->state != STARGET_CREATED);
 	starget->state = STARGET_DEL;
 	transport_destroy_device(dev);
 	spin_lock_irqsave(shost->host_lock, flags);
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 4f18a85..9e5f893 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1278,10 +1278,12 @@ void scsi_remove_target(struct device *dev)
 restart:
 	spin_lock_irqsave(shost->host_lock, flags);
 	list_for_each_entry(starget, &shost->__targets, siblings) {
-		if (starget->state == STARGET_DEL)
+		if (starget->state == STARGET_DEL ||
+		    starget->state == STARGET_REMOVE)
 			continue;
 		if (starget->dev.parent == dev || &starget->dev == dev) {
 			kref_get(&starget->reap_ref);
+			starget->state = STARGET_REMOVE;
 			spin_unlock_irqrestore(shost->host_lock, flags);
 			__scsi_remove_target(starget);
 			scsi_target_reap(starget);
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index f63a167..2bffaa6 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -240,6 +240,7 @@ scmd_printk(const char *, const struct scsi_cmnd *, const char *, ...);
 enum scsi_target_state {
 	STARGET_CREATED = 1,
 	STARGET_RUNNING,
+	STARGET_REMOVE,
 	STARGET_DEL,
 };
 
-- 
1.8.5.6