[rds-devel] cq event handler - using mutex

[Steve Wise]

Andy,

I think rds_ib_recv_cq_comp_handler() shouldn't be using a mutex.  If 
you turn on mutex debugging, you'll see a DEBUG_LOCKS_WARN_ON() from 
spin_lock_mutex() in kernel/mutex_debug.h because in_interrupt() is TRUE.

The RDMA kernel mode cq completion callback func is called from the 
interrupt context...


snipit from rds_ib_recv_cq_comp_handler():

------------
        if (mutex_trylock(&ic->i_recv_mutex)) {
                if (rds_ib_recv_refill(conn, GFP_ATOMIC,
                                         GFP_ATOMIC | __GFP_HIGHMEM, 0))
                        ret = -EAGAIN;
                else
                        rds_ib_stats_inc(s_ib_rx_refill_from_cq);
                mutex_unlock(&ic->i_recv_mutex);
        } else
                ret = -EAGAIN;
------------


Steve.