tree e6df3542a0a9dd36a8fa9939cdaeedf90f4884a5
parent 1732b0ef3b3a02e3df328086fb3018741c5476da
author Roland Dreier <rolandd@cisco.com> 1131388889 -0800
committer Roland Dreier <rolandd@cisco.com> 1131646970 -0800

[IB] umad: avoid potential deadlock when unregistering MAD agents

ib_unregister_mad_agent() completes all pending MAD sends and waits
for the agent's send_handler routine to return.  umad's send_handler()
calls queue_packet(), which does down_read() on the port mutex to look
up the agent ID.  This means that the port mutex cannot be held for
writing while calling ib_unregister_mad_agent(), or else it will
deadlock.  This patch fixes all the calls to ib_unregister_mad_agent()
in the umad module to avoid this deadlock.

Signed-off-by: Roland Dreier <rolandd@cisco.com>