[lkml]   [2011]   [Mar]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[11/78] IB/cm: Bump reference count on cm_id before invoking callback
2.6.38-stable review patch.  If anyone has any objections, please let us know.

From: Sean Hefty <>

commit 29963437a48475036353b95ab142bf199adb909e upstream.

When processing a SIDR REQ, the ib_cm allocates a new cm_id. The
refcount of the cm_id is initialized to 1. However, cm_process_work
will decrement the refcount after invoking all callbacks. The result
is that the cm_id will end up with refcount set to 0 by the end of the
sidr req handler.

If a user tries to destroy the cm_id, the destruction will proceed,
under the incorrect assumption that no other threads are referencing
the cm_id. This can lead to a crash when the cm callback thread tries
to access the cm_id.

This problem was noticed as part of a larger investigation with kernel
crashes in the rdma_cm when running on a real time OS.

Signed-off-by: Sean Hefty <>
Acked-by: Doug Ledford <>
Signed-off-by: Roland Dreier <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/infiniband/core/cm.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -2989,6 +2989,7 @@ static int cm_sidr_req_handler(struct cm
goto out; /* No match. */
+ atomic_inc(&cm_id_priv->refcount);

cm_id_priv->id.cm_handler = cur_cm_id_priv->id.cm_handler;

 \ /
  Last update: 2011-03-22 00:35    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean