linux-kernel - [PATCH 4.1 73/78] fnic: Use the local variable instead of I/O flag to acquire io_req_lock in fnic

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Date:	Fri, 11 Sep 2015 15:50:14 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Hiral Shah <hishah@...co.com>,
	Sesidhar Baddela <sebaddel@...co.com>,
	Anil Chintalapati <achintal@...co.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	James Bottomley <JBottomley@...n.com>
Subject: [PATCH 4.1 73/78] fnic: Use the local variable instead of I/O flag to acquire io_req_lock in fnic_queuecommand() to avoid deadloack

4.1-stable review patch.  If anyone has any objections, please let me know.

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

From: Hiral Shah <hishah@...co.com>

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.

Fixes: 41df7b02db82cf6c14f094757bac3830d10a827f
Signed-off-by: Hiral Shah <hishah@...co.com>
Signed-off-by: Sesidhar Baddela <sebaddel@...co.com>
Signed-off-by: Anil Chintalapati <achintal@...co.com>
Reviewed-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: James Bottomley <JBottomley@...n.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/drivers/scsi/fnic/fnic.h
+++ b/drivers/scsi/fnic/fnic.h
@@ -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: "
 
--- a/drivers/scsi/fnic/fnic_scsi.c
+++ b/drivers/scsi/fnic/fnic_scsi.c
@@ -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);


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