Patch "fnic: Use the local variable instead of I/O flag to acquire io_req_lock in fnic_queuecommand() to avoid deadloack" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

fnic: Use the local variable instead of I/O flag to acquire io_req_lock in fnic_queuecommand() to avoid deadloack

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
fnic-use-the-local-variable-instead-of-i-o-flag-to-acquire-io_req_lock-in-fnic_queuecommand-to-avoid-deadloack.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Hiral Shah <[email protected]>
Date: Tue, 14 Jul 2015 07:08:57 -0700
Subject: fnic: Use the local variable instead of I/O flag to acquire io_req_lock in fnic_queuecommand() to avoid deadloack

From: Hiral Shah <[email protected]>

commit db196935d9562abec4510f48d887bc1f1e054fcf upstream.

We added changes in fnic driver patch 1.6.0.16 to acquire io_req_lock in fnic_queuecommand() before issuing I/O so that io completion is serialized. But when releasing the lock we check for the I/O flag and this could be modified if IO abort occurs before I/O completion. In this case we wont release the lock and causes deadlock in some scenerios. Using the local variable to check the IO lock status will resolve the problem.

---
 drivers/scsi/fnic/fnic.h      |    2 +-
 drivers/scsi/fnic/fnic_scsi.c |    4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

@@ -39,7 +39,7 @@
 
 #define DRV_NAME		"fnic"
 #define DRV_DESCRIPTION		"Cisco FCoE HBA Driver"
-#define DRV_VERSION		"1.6.0.17"
+#define DRV_VERSION		"1.6.0.17a"
 #define PFX			DRV_NAME ": "
 #define DFX                     DRV_NAME "%d: "
 

@@ -425,6 +425,7 @@ static int fnic_queuecommand_lck(struct
 	unsigned long ptr;
 	struct fc_rport_priv *rdata;
 	spinlock_t *io_lock = NULL;
+	int io_lock_acquired = 0;
 
 	if (unlikely(fnic_chk_state_flags_locked(fnic, FNIC_FLAGS_IO_BLOCKED)))
 		return SCSI_MLQUEUE_HOST_BUSY;

@@ -518,6 +519,7 @@ static int fnic_queuecommand_lck(struct
 	spin_lock_irqsave(io_lock, flags);
 
 	/* initialize rest of io_req */
+	io_lock_acquired = 1;
 	io_req->port_id = rport->port_id;
 	io_req->start_time = jiffies;
 	CMD_STATE(sc) = FNIC_IOREQ_CMD_PENDING;

@@ -571,7 +573,7 @@ out:
 		  (((u64)CMD_FLAGS(sc) >> 32) | CMD_STATE(sc)));
 
 	/* if only we issued IO, will we have the io lock */
-	if (CMD_FLAGS(sc) & FNIC_IO_INITIALIZED)
+	if (io_lock_acquired)
 		spin_unlock_irqrestore(io_lock, flags);
 
 	atomic_dec(&fnic->in_flight);

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/fnic-use-the-local-variable-instead-of-i-o-flag-to-acquire-io_req_lock-in-fnic_queuecommand-to-avoid-deadloack.patch