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[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: Chris Leech <christopher.leech@intel.com> Signed-off-by: Robert Love <robert.w.love@intel.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
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parent
c826a31457
commit
55c8bafba5
1 changed files with 24 additions and 57 deletions
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@ -70,8 +70,6 @@ struct fcoe_percpu_s *fcoe_percpu[NR_CPUS];
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/* Function Prototyes */
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static int fcoe_check_wait_queue(struct fc_lport *);
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static void fcoe_insert_wait_queue_head(struct fc_lport *, struct sk_buff *);
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static void fcoe_insert_wait_queue(struct fc_lport *, struct sk_buff *);
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static void fcoe_recv_flogi(struct fcoe_softc *, struct fc_frame *, u8 *);
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#ifdef CONFIG_HOTPLUG_CPU
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static int fcoe_cpu_callback(struct notifier_block *, ulong, void *);
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@ -501,7 +499,9 @@ int fcoe_xmit(struct fc_lport *lp, struct fc_frame *fp)
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rc = fcoe_start_io(skb);
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if (rc) {
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fcoe_insert_wait_queue(lp, skb);
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spin_lock_bh(&fc->fcoe_pending_queue.lock);
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__skb_queue_tail(&fc->fcoe_pending_queue, skb);
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spin_unlock_bh(&fc->fcoe_pending_queue.lock);
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if (fc->fcoe_pending_queue.qlen > FCOE_MAX_QUEUE_DEPTH)
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lp->qfull = 1;
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}
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@ -756,33 +756,36 @@ void fcoe_watchdog(ulong vp)
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*/
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static int fcoe_check_wait_queue(struct fc_lport *lp)
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{
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struct fcoe_softc *fc = lport_priv(lp);
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struct sk_buff *skb;
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struct fcoe_softc *fc;
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int rc = -1;
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fc = lport_priv(lp);
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spin_lock_bh(&fc->fcoe_pending_queue.lock);
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if (fc->fcoe_pending_queue_active)
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goto out;
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fc->fcoe_pending_queue_active = 1;
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if (fc->fcoe_pending_queue.qlen) {
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while ((skb = __skb_dequeue(&fc->fcoe_pending_queue)) != NULL) {
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spin_unlock_bh(&fc->fcoe_pending_queue.lock);
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rc = fcoe_start_io(skb);
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if (rc)
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fcoe_insert_wait_queue_head(lp, skb);
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spin_lock_bh(&fc->fcoe_pending_queue.lock);
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if (rc)
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break;
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while (fc->fcoe_pending_queue.qlen) {
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/* keep qlen > 0 until fcoe_start_io succeeds */
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fc->fcoe_pending_queue.qlen++;
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skb = __skb_dequeue(&fc->fcoe_pending_queue);
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spin_unlock_bh(&fc->fcoe_pending_queue.lock);
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rc = fcoe_start_io(skb);
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spin_lock_bh(&fc->fcoe_pending_queue.lock);
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if (rc) {
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__skb_queue_head(&fc->fcoe_pending_queue, skb);
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/* undo temporary increment above */
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fc->fcoe_pending_queue.qlen--;
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break;
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}
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/*
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* if interface pending queue is below FCOE_LOW_QUEUE_DEPTH
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* then clear qfull flag.
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*/
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if (fc->fcoe_pending_queue.qlen < FCOE_LOW_QUEUE_DEPTH)
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lp->qfull = 0;
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/* undo temporary increment above */
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fc->fcoe_pending_queue.qlen--;
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}
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if (fc->fcoe_pending_queue.qlen < FCOE_LOW_QUEUE_DEPTH)
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lp->qfull = 0;
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fc->fcoe_pending_queue_active = 0;
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rc = fc->fcoe_pending_queue.qlen;
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out:
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@ -790,42 +793,6 @@ static int fcoe_check_wait_queue(struct fc_lport *lp)
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return rc;
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}
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/**
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* fcoe_insert_wait_queue_head() - puts skb to fcoe pending queue head
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* @lp: the fc_port for this skb
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* @skb: the associated skb to be xmitted
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*
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* Returns: none
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*/
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static void fcoe_insert_wait_queue_head(struct fc_lport *lp,
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struct sk_buff *skb)
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{
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struct fcoe_softc *fc;
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fc = lport_priv(lp);
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spin_lock_bh(&fc->fcoe_pending_queue.lock);
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__skb_queue_head(&fc->fcoe_pending_queue, skb);
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spin_unlock_bh(&fc->fcoe_pending_queue.lock);
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}
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/**
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* fcoe_insert_wait_queue() - put the skb into fcoe pending queue tail
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* @lp: the fc_port for this skb
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* @skb: the associated skb to be xmitted
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*
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* Returns: none
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*/
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static void fcoe_insert_wait_queue(struct fc_lport *lp,
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struct sk_buff *skb)
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{
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struct fcoe_softc *fc;
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fc = lport_priv(lp);
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spin_lock_bh(&fc->fcoe_pending_queue.lock);
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__skb_queue_tail(&fc->fcoe_pending_queue, skb);
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spin_unlock_bh(&fc->fcoe_pending_queue.lock);
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}
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/**
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* fcoe_dev_setup() - setup link change notification interface
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*/
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