[openib-general] APM support in openib stack

[Venkatesh Babu]

I see your point. With my ULP module this was not the case, since this
was the only module which was registering during the module init and
unregistering during module exit. From the generic OFED stack's
perspective, you are right. This condition needs to be addressed. This
possibility exists in other interfaces of sa_query.c also.

 VBabu

Sean Hefty wrote:

 > Venkatesh Babu wrote:
 >
 >> The patch for ib_sa_serv_notice_hdlr() handles multiple callers
 >> registering for the same event by maintaining a linked list of
 >> callback handlers. So I didn't think that the multiple user count was
 >> necessary. The actual registration with the MAD layer happens only
 >> when the ib_sa module is initialized and unregistered when it is
 >> unloaded.
 >
 >
 > Since MADs can be delivered / processed out of order, there's a race
 > if one user unregisters for events at the same time another user tries
 > to register.  The second user can be left unregistered.  Requests to
 > the SA for the same event must be serialized to ensure that we are
 > left in the proper registration state.
 >
 > The problem becomes more complex when a user cancels their request
 > while it's still being processed.
 >
 > - Sean