[mvapich-discuss] Mutex in mv2_get_path_rec_sl

[Alexander Melnikov]

The mv2_get_path_rec_sl function can be called simultaneously from two
different threads (main and cm_completion_handler), therefore it is
necessary to use a mutex in it to access shared resources (SL cache,
read/write buffer).
Call chains that lead to conflicts:
-
PMPI_Init->MPIR_Init_thread->MPID_Init->MPIDI_CH3_Init->MPIDI_CH3I_CM_Init->MPIDI_CH3I_Exchange_Init_Info->MPIDI_CH3I_Ring_Exchange_Init_Info->rdma_setup_startup_ring->mv2_get_path_rec_sl
- cm_completion_handler->cm_handle_msg->cm_qp_move_to_rtr->mv2_get_path_rec_sl

In the MPI application we will see the following messages:
- No response from SA
And in the opensm log the following message may appear:
osm_vendor_send: ERR 5430: Send p_madw = 0x7f5ec8001c30 of size 120, Class
0x3, Method 0x81, Attr 0x35, TID 0x234103ca1200efbe failed -5 (Invalid
argument)

The simplest solution is to use mutex as in the attached patch.
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