[SCSI] fcoe: Out of order tx frames was causing several check condition SCSI status
frames followed by these errors in log.
[sdp] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE,SUGGEST_OK
[sdp] Sense Key : Aborted Command [current]
[sdp] Add. Sense: Data phase error
This was causing some test apps to exit due to write failure under heavy
load.
This was due to a race around adding and removing tx frame skb in
fcoe_pending_queue, Chris Leech helped me to find that brief unlocking
period when pulling skb from fcoe_pending_queue in various contexts
(fcoe_watchdog and fcoe_xmit) and then adding skb back into fcoe_pending_queue
up on a failed fcoe_start_io could change skb/tx frame order in
fcoe_pending_queue. Thanks Chris.
This patch allows only single context to pull skb from fcoe_pending_queue
at any time to prevent above described ordering issue/race by use of
fcoe_pending_queue_active flag.
This patch simplified fcoe_watchdog with modified fcoe_check_wait_queue by
use of FCOE_LOW_QUEUE_DEPTH instead previously used several conditionals
to clear and set lp->qfull.
I think FCOE_MAX_QUEUE_DEPTH with FCOE_LOW_QUEUE_DEPTH will work better
in re/setting lp->qfull and these could be fine tuned for performance.
Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/fcoe/libfcoe.c b/drivers/scsi/fcoe/libfcoe.c
index 7265e09..14dd8a0 100644
--- a/drivers/scsi/fcoe/libfcoe.c
+++ b/drivers/scsi/fcoe/libfcoe.c
@@ -49,6 +49,7 @@
static int debug_fcoe;
#define FCOE_MAX_QUEUE_DEPTH 256
+#define FCOE_LOW_QUEUE_DEPTH 32
/* destination address mode */
#define FCOE_GW_ADDR_MODE 0x00
@@ -723,21 +724,12 @@
*/
void fcoe_watchdog(ulong vp)
{
- struct fc_lport *lp;
struct fcoe_softc *fc;
- int qfilled = 0;
read_lock(&fcoe_hostlist_lock);
list_for_each_entry(fc, &fcoe_hostlist, list) {
- lp = fc->lp;
- if (lp) {
- if (fc->fcoe_pending_queue.qlen > FCOE_MAX_QUEUE_DEPTH)
- qfilled = 1;
- if (fcoe_check_wait_queue(lp) < FCOE_MAX_QUEUE_DEPTH) {
- if (qfilled)
- lp->qfull = 0;
- }
- }
+ if (fc->lp)
+ fcoe_check_wait_queue(fc->lp);
}
read_unlock(&fcoe_hostlist_lock);
@@ -753,8 +745,8 @@
*
* This empties the wait_queue, dequeue the head of the wait_queue queue
* and calls fcoe_start_io() for each packet, if all skb have been
- * transmitted, return 0 if a error occurs, then restore wait_queue and
- * try again later.
+ * transmitted, return qlen or -1 if a error occurs, then restore
+ * wait_queue and try again later.
*
* The wait_queue is used when the skb transmit fails. skb will go
* in the wait_queue which will be emptied by the time function OR
@@ -764,33 +756,38 @@
*/
static int fcoe_check_wait_queue(struct fc_lport *lp)
{
- int rc;
struct sk_buff *skb;
struct fcoe_softc *fc;
+ int rc = -1;
fc = lport_priv(lp);
spin_lock_bh(&fc->fcoe_pending_queue.lock);
- /*
- * if interface pending queue full then set qfull in lport.
- */
- if (fc->fcoe_pending_queue.qlen > FCOE_MAX_QUEUE_DEPTH)
- lp->qfull = 1;
+ 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) {
+ if (rc)
fcoe_insert_wait_queue_head(lp, skb);
- return rc;
- }
spin_lock_bh(&fc->fcoe_pending_queue.lock);
+ if (rc)
+ break;
}
- if (fc->fcoe_pending_queue.qlen < FCOE_MAX_QUEUE_DEPTH)
+ /*
+ * 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;
}
+ fc->fcoe_pending_queue_active = 0;
+ rc = fc->fcoe_pending_queue.qlen;
+out:
spin_unlock_bh(&fc->fcoe_pending_queue.lock);
- return fc->fcoe_pending_queue.qlen;
+ return rc;
}
/**