[PATCH] IB: Fix timeout/cancelled MAD handling

Fixes an issue processing a sent MAD after it has timed out or been canceled.
The race occurs when a response MAD matches with the send request.  The
request could time out or be canceled after the response MAD matches with the
request, but before the request completion can be processed.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Hal Rosenstock <halr@voltaire.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 12 insertions, 2 deletions

diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index d1898b30c34..7af8f7f8784 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -341,6 +341,7 @@ struct ib_mad_agent *ib_register_mad_agent(struct ib_device *device,
         spin_lock_init(&mad_agent_priv->lock);
         INIT_LIST_HEAD(&mad_agent_priv->send_list);
         INIT_LIST_HEAD(&mad_agent_priv->wait_list);
+        INIT_LIST_HEAD(&mad_agent_priv->done_list);
         INIT_WORK(&mad_agent_priv->timed_work, timeout_sends, mad_agent_priv);
         INIT_LIST_HEAD(&mad_agent_priv->local_list);
         INIT_WORK(&mad_agent_priv->local_work, local_completions,
@@ -1559,6 +1560,16 @@ find_send_req(struct ib_mad_agent_private *mad_agent_priv,
         return NULL;
 }
 
+static void ib_mark_req_done(struct ib_mad_send_wr_private *mad_send_wr)
+{
+        mad_send_wr->timeout = 0;
+        if (mad_send_wr->refcount == 1) {
+                list_del(&mad_send_wr->agent_list);
+                list_add_tail(&mad_send_wr->agent_list,
+                              &mad_send_wr->mad_agent_priv->done_list);
+        }
+}
+
 static void ib_mad_complete_recv(struct ib_mad_agent_private *mad_agent_priv,
                                  struct ib_mad_recv_wc *mad_recv_wc)
 {
@@ -1580,8 +1591,7 @@ static void ib_mad_complete_recv(struct ib_mad_agent_private *mad_agent_priv,
                                 wake_up(&mad_agent_priv->wait);
                         return;
                 }
-                /* Timeout = 0 means that we won't wait for a response */
-                mad_send_wr->timeout = 0;
+                ib_mark_req_done(mad_send_wr);
                 spin_unlock_irqrestore(&mad_agent_priv->lock, flags);
 
                 /* Defined behavior is to complete response before request */