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IPoIB: Fix crash when path record fails after path flush 

Commit ee1e2c82 ("IPoIB: Refresh paths instead of flushing them on SM
change events") changed how paths are flushed on an SM event.  This
change introduces a problem if the path record query triggered by
fails, causing path->ah to become NULL.  A later successful path query
will then trigger WARN_ON() in path_rec_completion(), and crash
because path->ah has already been freed, so the ipoib_put_ah() inside
the lock in path_rec_completion() may actually drop the last reference
(contrary to the comment that claims this is safe).

Fix this by updating path->ah and freeing old_ah only when the path
record query is successful.  This prevents the neighbour AH and that
path AH from getting out of sync.

This fixes <https://bugs.openfabrics.org/show_bug.cgi?id=1194>

Reported-by: Rabah Salem <ravah@mellanox.com>
Debugged-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Roland Dreier 2008-09-25 15:28:08 -07:00 committed by Linus Torvalds
parent efba91bd90
commit 6ef190cc92
1 changed files with 4 additions and 4 deletions
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8
drivers/infiniband/ulp/ipoib/ipoib_main.c
View File

@ -404,7 +404,7 @@ static void path_rec_completion(int status,
struct net_device *dev = path->dev;
struct ipoib_dev_priv *priv = netdev_priv(dev);
struct ipoib_ah *ah = NULL;
struct ipoib_ah *old_ah;
struct ipoib_ah *old_ah = NULL;
struct ipoib_neigh *neigh, *tn;
struct sk_buff_head skqueue;
struct sk_buff *skb;
@ -428,12 +428,12 @@ static void path_rec_completion(int status,
spin_lock_irqsave(&priv->lock, flags);
old_ah = path->ah;
path->ah = ah;
if (ah) {
path->pathrec = *pathrec;
old_ah = path->ah;
path->ah = ah;
ipoib_dbg(priv, "created address handle %p for LID 0x%04x, SL %d\n",
ah, be16_to_cpu(pathrec->dlid), pathrec->sl);