Commit 55c8bafb authored by Chris Leech's avatar Chris Leech Committed by James Bottomley
Browse files

[SCSI] fcoe: fix handling of pending queue, prevent out of order frames (v3) 



In fcoe_check_wait_queue() the queue length could temporarily drop to 0,
before the last frame was successfully sent.  This resulted in out of order
data frames within a single sequence, leading to IO timeout errors.

This builds on the approach from Vasu Dev to only fix the queue management in
fcoe_check_wait_queue, where my first patch added locking to the transmit
path even when the pending queue was not in use.

This patch continues to use fcoe_pending_queue.qlen instead of introducing a
new length counter, but takes precautions to ensure it never drops to 0 before
the final frame in the queue has successfully been passed to the netdev qdisc
layer.  It also includes some cleanup of fcoe_check_wait_queue and removes the
fcoe_insert_wait_queue(_head) wrapper functions.

Signed-off-by: default avatarChris Leech <christopher.leech@intel.com>
Signed-off-by: default avatarRobert Love <robert.w.love@intel.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent c826a314

drivers/scsi/fcoe/libfcoe.c

+24 −57
Original line number Diff line number Diff line
@@ -70,8 +70,6 @@ struct fcoe_percpu_s *fcoe_percpu[NR_CPUS]; 


/* Function Prototyes */

static int fcoe_check_wait_queue(struct fc_lport *);

static void fcoe_insert_wait_queue_head(struct fc_lport *, struct sk_buff *);

static void fcoe_insert_wait_queue(struct fc_lport *, struct sk_buff *);

static void fcoe_recv_flogi(struct fcoe_softc *, struct fc_frame *, u8 *);

#ifdef CONFIG_HOTPLUG_CPU

static int fcoe_cpu_callback(struct notifier_block *, ulong, void *);
@@ -501,7 +499,9 @@ int fcoe_xmit(struct fc_lport *lp, struct fc_frame *fp) 
		rc = fcoe_start_io(skb);



	if (rc) {

		fcoe_insert_wait_queue(lp, skb);

		spin_lock_bh(&fc->fcoe_pending_queue.lock);

		__skb_queue_tail(&fc->fcoe_pending_queue, skb);

		spin_unlock_bh(&fc->fcoe_pending_queue.lock);

		if (fc->fcoe_pending_queue.qlen > FCOE_MAX_QUEUE_DEPTH)

			lp->qfull = 1;

	}
@@ -756,33 +756,36 @@ void fcoe_watchdog(ulong vp) 
 */

static int fcoe_check_wait_queue(struct fc_lport *lp)

{

	struct fcoe_softc *fc = lport_priv(lp);

	struct sk_buff *skb;

	struct fcoe_softc *fc;

	int rc = -1;



	fc = lport_priv(lp);

	spin_lock_bh(&fc->fcoe_pending_queue.lock);



	if (fc->fcoe_pending_queue_active)

		goto out;

	fc->fcoe_pending_queue_active = 1;

	if (fc->fcoe_pending_queue.qlen) {

		while ((skb = __skb_dequeue(&fc->fcoe_pending_queue)) != NULL) {



	while (fc->fcoe_pending_queue.qlen) {

		/* keep qlen > 0 until fcoe_start_io succeeds */

		fc->fcoe_pending_queue.qlen++;

		skb = __skb_dequeue(&fc->fcoe_pending_queue);



		spin_unlock_bh(&fc->fcoe_pending_queue.lock);

		rc = fcoe_start_io(skb);

			if (rc)

				fcoe_insert_wait_queue_head(lp, skb);

		spin_lock_bh(&fc->fcoe_pending_queue.lock);

			if (rc)



		if (rc) {

			__skb_queue_head(&fc->fcoe_pending_queue, skb);

			/* undo temporary increment above */

			fc->fcoe_pending_queue.qlen--;

			break;

		}

		/*

		 * if interface pending queue is below FCOE_LOW_QUEUE_DEPTH

		 * then clear qfull flag.

		 */

		/* undo temporary increment above */

		fc->fcoe_pending_queue.qlen--;

	}



	if (fc->fcoe_pending_queue.qlen < FCOE_LOW_QUEUE_DEPTH)

		lp->qfull = 0;

	}

	fc->fcoe_pending_queue_active = 0;

	rc = fc->fcoe_pending_queue.qlen;

out:
@@ -790,42 +793,6 @@ out: 
	return rc;

}



/**

 * fcoe_insert_wait_queue_head() - puts skb to fcoe pending queue head

 * @lp: the fc_port for this skb

 * @skb: the associated skb to be xmitted

 *

 * Returns: none

 */

static void fcoe_insert_wait_queue_head(struct fc_lport *lp,

					struct sk_buff *skb)

{

	struct fcoe_softc *fc;



	fc = lport_priv(lp);

	spin_lock_bh(&fc->fcoe_pending_queue.lock);

	__skb_queue_head(&fc->fcoe_pending_queue, skb);

	spin_unlock_bh(&fc->fcoe_pending_queue.lock);

}



/**

 * fcoe_insert_wait_queue() - put the skb into fcoe pending queue tail

 * @lp: the fc_port for this skb

 * @skb: the associated skb to be xmitted

 *

 * Returns: none

 */

static void fcoe_insert_wait_queue(struct fc_lport *lp,

				   struct sk_buff *skb)

{

	struct fcoe_softc *fc;



	fc = lport_priv(lp);

	spin_lock_bh(&fc->fcoe_pending_queue.lock);

	__skb_queue_tail(&fc->fcoe_pending_queue, skb);

	spin_unlock_bh(&fc->fcoe_pending_queue.lock);

}



/**

 * fcoe_dev_setup() - setup link change notification interface

 */

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