164ba0893c
This patch solves a race that occurs after an event occurs that causes the SA query module to flush its SM address handle (AH). When SM AH becomes invalid and needs an update it is handled by the global workqueue. On the other hand this event is also handled in the IPoIB driver by queuing work in the ipoib_workqueue that does multicast joins. Although queuing is in the right order, it is done to 2 different workqueues and so there is no guarantee that the first to be queued is the first to be executed. This causes a problem because IPoIB may end up sending an request to the old SM, which will take a long time to time out (since the old SM is gone); this leads to a much longer than necessary interruption in multicast traffer. The patch sets the SA query module's SM AH to NULL when the event occurs, and until update_sm_ah() is done, any request that needs sm_ah fails with -EAGAIN return status. For consumers, the patch doesn't make things worse. Before the patch, MADs are sent to the wrong SM so the request gets lost. Consumers can be improved if they examine the return code and respond to EAGAIN properly but even without an improvement the situation is not getting worse. Signed-off-by: Moni Levy <monil@voltaire.com> Signed-off-by: Moni Shoua <monis@voltaire.com> Signed-off-by: Roland Dreier <rolandd@cisco.com> |
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