From: Chris Leech <christopher.leech@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Robert Love <robert.w.love@xxxxxxxxx>
---
drivers/scsi/fcoe/libfcoe.c | 81 +++++++++++++------------------------------
1 files changed, 24 insertions(+), 57 deletions(-)
diff --git a/drivers/scsi/fcoe/libfcoe.c b/drivers/scsi/fcoe/libfcoe.c
index 14dd8a0..0e0b494 100644
--- a/drivers/scsi/fcoe/libfcoe.c
+++ b/drivers/scsi/fcoe/libfcoe.c
@@ -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) {
- 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)
- break;
+
+ 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);
+ spin_lock_bh(&fc->fcoe_pending_queue.lock);
+
+ 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.
- */
- if (fc->fcoe_pending_queue.qlen < FCOE_LOW_QUEUE_DEPTH)
- lp->qfull = 0;
+ /* 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:
@@ -791,42 +794,6 @@ out:
}
/**
- * 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
*/
static void fcoe_dev_setup()
--
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