linux-kernel - [PATCH 3.19.y-ckt 071/102] fnic: Use the local variable instead of I/O flag to acquire io_req_lock in fnic

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Message-Id: <1442944358-1248-72-git-send-email-kamal@canonical.com>
Date:	Tue, 22 Sep 2015 10:52:07 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Hiral Shah <hishah@...co.com>,
	Sesidhar Baddela <sebaddel@...co.com>,
	Anil Chintalapati <achintal@...co.com>,
	James Bottomley <JBottomley@...n.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 071/102] fnic: Use the local variable instead of I/O flag to acquire io_req_lock in fnic_queuecommand() to avoid deadloack

3.19.8-ckt7 -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: Kamal Mostafa <kamal@...onical.com>
---
 drivers/scsi/fnic/fnic.h      | 2 +-
 drivers/scsi/fnic/fnic_scsi.c | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/fnic/fnic.h b/drivers/scsi/fnic/fnic.h
index 26270c3..ce129e5 100644
--- 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: "
 
diff --git a/drivers/scsi/fnic/fnic_scsi.c b/drivers/scsi/fnic/fnic_scsi.c
index 155b286..25436cd 100644
--- a/drivers/scsi/fnic/fnic_scsi.c
+++ b/drivers/scsi/fnic/fnic_scsi.c
@@ -425,6 +425,7 @@ static int fnic_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi_
 	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 scsi_cmnd *sc, void (*done)(struct scsi_
 	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);
-- 
1.9.1

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