Messages in this thread Patch in this message | | | From | Paul Gortmaker <> | Subject | [34-longterm 178/247] IB/cm: Bump reference count on cm_id before invoking callback | Date | Thu, 23 Jun 2011 13:34:06 -0400 |
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From: Sean Hefty <sean.hefty@intel.com>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. -------------------
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 <sean.hefty@intel.com> Acked-by: Doug Ledford <dledford@redhat.com> Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- drivers/infiniband/core/cm.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c index ad63b79..2422945 100644 --- a/drivers/infiniband/core/cm.c +++ b/drivers/infiniband/core/cm.c @@ -2987,6 +2987,7 @@ static int cm_sidr_req_handler(struct cm_work *work) goto out; /* No match. */ } atomic_inc(&cur_cm_id_priv->refcount); + atomic_inc(&cm_id_priv->refcount); spin_unlock_irq(&cm.lock); cm_id_priv->id.cm_handler = cur_cm_id_priv->id.cm_handler; -- 1.7.4.4
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