Hello Don Hiatt,
The patch f8195f3b14a0: "IB/hfi1: Eliminate allocation while atomic"
from Oct 9, 2017, leads to the following static checker warning:
drivers/infiniband/hw/hfi1/verbs.c:824 build_verbs_tx_desc()
error: doing dma on the stack (trail_buf)
drivers/infiniband/hw/hfi1/verbs.c
147 /* Length of buffer to create verbs txreq cache name */
148 #define TXREQ_NAME_LEN 24
149
150 /* 16B trailing buffer */
151 static const u8 trail_buf[MAX_16B_PADDING];
^^^^^^^^^^^^^^^^^^^^^^^^^^
This used to be actually allocated on the stack but now it's here. I
believe this is still a problem. It's not a problem for most people at
runtime, but it's technically a bug. And I believe that soon we will
add a check in dma_map_single() which will generate a warning.
152
153 static uint wss_threshold = 80;
[ snip ]
801 } else {
802 ret = sdma_txinit_ahg(
803 &tx->txreq,
804 ahg_info->tx_flags,
805 length,
806 ahg_info->ahgidx,
807 ahg_info->ahgcount,
808 ahg_info->ahgdesc,
809 hdrbytes,
810 verbs_sdma_complete);
811 if (ret)
812 goto bail_txadd;
813 }
814 /* add the ulp payload - if any. tx->ss can be NULL for acks */
815 if (tx->ss) {
816 ret = build_verbs_ulp_payload(sde, length, tx);
817 if (ret)
818 goto bail_txadd;
819 }
820
821 /* add icrc, lt byte, and padding to flit */
822 if (extra_bytes)
823 ret = sdma_txadd_kvaddr(sde->dd, &tx->txreq,
824 (void *)trail_buf, extra_bytes);
^^^^^^^^^
This has to be DMAable memory.
825
826 bail_txadd:
827 return ret;
828 }
regards,
dan carpenter
