> I prefer the original patch, the reason is: drain_list only have one
> element, which the first of of the flush list, whenever its drain WR
> processed, it will be put in reap_list, why we need drain_list here?
Maybe I'm missing something. If we get rid of drain_list, how does
ipoib_cm_start_rx_drain() know if a drain WQE is pending or not?
I guess we can look at how many entries the flush_list has, something
like this? (compile tested only)
commit 17120d826ec4c12f71d075b69a836f0d4f5ac499
Author: Roland Dreier <[EMAIL PROTECTED]>
Date: Wed Jun 25 14:05:17 2008 -0700
IPoIB/cm: Drain receive QPs one at a time
The current handling of last WQE reached events is broken when
multiple QPs are drained at once -- for example:
1. Last WQE reached event for QP100: QP100 context is added into
flush_list, and then it is put into drain_list, and does post_send
of a drain WR.
2. Last WQE reached event for QP200: QP200 context is added into
flush_list, but not drain_list since only one drain WR will be
posted.
3. Last WQE reached event for QP300: QP300 context is added into
flush_list, but not drain_list since only one drain WR will be
posted.
So at this point, QP100 is on drain_list and QP200 and QP300 are on
flush_list.
4. QP100 drain WR CQE is handled: put QP100 into reap_list then call
ipoib_cm_start_rx_drain(), which does post_send of QP200 drain WR,
and moves both QP200 and QP300 from flush_list to drain_list.
5. QP200 drain WR CQE is polled, which will move both QP200 and QP300
from drain_list to reap_list.
6. QP200 and QP300 are both freed from reap_list.
7. A CQE for QP300 is seen, but QP300 context has been freed ---> crash.
The fundamental problem is that a last WQE reached event does not mean
all pending completions have been queued.
Fix this by flushing QPs from the flush_list one at a time, so that we
never free QPs until we really know that we are done with them. This
allows us to simplify the code by removing the drain_list completely
(since we flush one at a time, the context to move to the reap_list when
the drain WQE completes is always just the first entry in flush_list).
Debugged-by: Shirley Ma <[EMAIL PROTECTED]>
Fix-suggested-by: Eli Cohen <[EMAIL PROTECTED]>
Signed-off-by: Roland Dreier <[EMAIL PROTECTED]>
diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h
b/drivers/infiniband/ulp/ipoib/ipoib.h
index 8754b36..c02e3b0 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -224,8 +224,7 @@ struct ipoib_cm_dev_priv {
struct ib_cm_id *id;
struct list_head passive_ids; /* state: LIVE */
struct list_head rx_error_list; /* state: ERROR */
- struct list_head rx_flush_list; /* state: FLUSH, drain not
started */
- struct list_head rx_drain_list; /* state: FLUSH, drain started */
+ struct list_head rx_flush_list; /* state: FLUSHING or waiting
for FLUSH */
struct list_head rx_reap_list; /* state: FLUSH, drain done */
struct work_struct start_task;
struct work_struct reap_task;
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index 6223fc3..07939ed 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -208,21 +208,13 @@ static void ipoib_cm_start_rx_drain(struct ipoib_dev_priv
*priv)
struct ib_send_wr *bad_wr;
struct ipoib_cm_rx *p;
- /* We only reserved 1 extra slot in CQ for drain WRs, so
- * make sure we have at most 1 outstanding WR. */
- if (list_empty(&priv->cm.rx_flush_list) ||
- !list_empty(&priv->cm.rx_drain_list))
- return;
-
/*
* QPs on flush list are error state. This way, a "flush
* error" WC will be immediately generated for each WR we post.
*/
- p = list_entry(priv->cm.rx_flush_list.next, typeof(*p), list);
+ p = list_first_entry(&priv->cm.rx_flush_list, typeof(*p), list);
if (ib_post_send(p->qp, &ipoib_cm_rx_drain_wr, &bad_wr))
ipoib_warn(priv, "failed to post drain wr\n");
-
- list_splice_init(&priv->cm.rx_flush_list, &priv->cm.rx_drain_list);
}
static void ipoib_cm_rx_event_handler(struct ib_event *event, void *ctx)
@@ -235,9 +227,15 @@ static void ipoib_cm_rx_event_handler(struct ib_event
*event, void *ctx)
return;
spin_lock_irqsave(&priv->lock, flags);
- list_move(&p->list, &priv->cm.rx_flush_list);
+
+ list_move_tail(&p->list, &priv->cm.rx_flush_list);
p->state = IPOIB_CM_RX_FLUSH;
- ipoib_cm_start_rx_drain(priv);
+
+ /* We only reserved 1 extra slot in CQ for drain WRs, so
+ * make sure we have at most 1 outstanding WR. */
+ if (list_is_singular(&priv->cm.rx_flush_list))
+ ipoib_cm_start_rx_drain(priv);
+
spin_unlock_irqrestore(&priv->lock, flags);
}
@@ -531,8 +529,9 @@ void ipoib_cm_handle_rx_wc(struct net_device *dev, struct
ib_wc *wc)
if (unlikely(wr_id >= ipoib_recvq_size)) {
if (wr_id == (IPOIB_CM_RX_DRAIN_WRID & ~(IPOIB_OP_CM |
IPOIB_OP_RECV))) {
spin_lock_irqsave(&priv->lock, flags);
- list_splice_init(&priv->cm.rx_drain_list,
&priv->cm.rx_reap_list);
- ipoib_cm_start_rx_drain(priv);
+ list_move(&priv->cm.rx_flush_list,
&priv->cm.rx_reap_list);
+ if (!list_empty(&priv->cm.rx_flush_list))
+ ipoib_cm_start_rx_drain(priv);
queue_work(ipoib_workqueue, &priv->cm.rx_reap_task);
spin_unlock_irqrestore(&priv->lock, flags);
} else
@@ -867,8 +866,7 @@ void ipoib_cm_dev_stop(struct net_device *dev)
begin = jiffies;
while (!list_empty(&priv->cm.rx_error_list) ||
- !list_empty(&priv->cm.rx_flush_list) ||
- !list_empty(&priv->cm.rx_drain_list)) {
+ !list_empty(&priv->cm.rx_flush_list)) {
if (time_after(jiffies, begin + 5 * HZ)) {
ipoib_warn(priv, "RX drain timing out\n");
@@ -879,8 +877,6 @@ void ipoib_cm_dev_stop(struct net_device *dev)
&priv->cm.rx_reap_list);
list_splice_init(&priv->cm.rx_error_list,
&priv->cm.rx_reap_list);
- list_splice_init(&priv->cm.rx_drain_list,
- &priv->cm.rx_reap_list);
break;
}
spin_unlock_irq(&priv->lock);
@@ -1472,7 +1468,6 @@ int ipoib_cm_dev_init(struct net_device *dev)
INIT_LIST_HEAD(&priv->cm.start_list);
INIT_LIST_HEAD(&priv->cm.rx_error_list);
INIT_LIST_HEAD(&priv->cm.rx_flush_list);
- INIT_LIST_HEAD(&priv->cm.rx_drain_list);
INIT_LIST_HEAD(&priv->cm.rx_reap_list);
INIT_WORK(&priv->cm.start_task, ipoib_cm_tx_start);
INIT_WORK(&priv->cm.reap_task, ipoib_cm_tx_reap);
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