[ofa-general] [PATCH 1/2] IB/core: handle race between elements in qork queues after event

[Roland Dreier]

I asked you to resend with the race fixed.  However I guess I never
spelled out what race I meant ... I thought I pointed this out, but
looking at the archives I don't see it.

So think about this:

What happens if someone calls ib_sa_path_rec_get() and

	@@ -663,6 +674,8 @@ int ib_sa_path_rec_get(struct ib_sa_client *client,
	 		return -ENODEV;
	 
	 	port  = &sa_dev->port[port_num - sa_dev->start_port];
	+	if (!port->sm_ah)
	+		return  -EAGAIN;

right about here (*after* the test), ib_sa_event() does "port->sm_ah = NULL;"
on another CPU.

	 	agent = port->agent;
	 
	 	query = kmalloc(sizeof *query, gfp_mask);