IB/rxe: Add support for zero-byte operations

The last_psn algorithm fails in the zero-byte case: it calculates
first_psn = N, last_psn = N-1. This makes the operation unretryable since
the res structure will fail the (first_psn <= psn <= last_psn) test in
find_resource().

While here, use BTH_PSN_MASK to mask the calculated last_psn.

Signed-off-by: Andrew Boyer <andrew.boyer@dell.com>
Reviewed-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
index 1869152..d0faca2 100644 (file)
--- a/drivers/infiniband/sw/rxe/rxe_mr.c
+++ b/drivers/infiniband/sw/rxe/rxe_mr.c
@@ -355,6 +355,9 @@ int rxe_mem_copy(struct rxe_mem *mem, u64 iova, void *addr, int length,
        size_t                  offset;
        u32                     crc = crcp ? (*crcp) : 0;
 
+       if (length == 0)
+               return 0;
+
        if (mem->type == RXE_MEM_TYPE_DMA) {
                u8 *src, *dest;
 

diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
index cb3fd4c..a5e9ce3 100644 (file)
--- a/drivers/infiniband/sw/rxe/rxe_resp.c
+++ b/drivers/infiniband/sw/rxe/rxe_resp.c
@@ -444,6 +444,13 @@ static enum resp_states check_rkey(struct rxe_qp *qp,
                return RESPST_EXECUTE;
        }
 
+       /* A zero-byte op is not required to set an addr or rkey. */
+       if ((pkt->mask & (RXE_READ_MASK | RXE_WRITE_OR_SEND)) &&
+           (pkt->mask & RXE_RETH_MASK) &&
+           reth_len(pkt) == 0) {
+               return RESPST_EXECUTE;
+       }
+
        va      = qp->resp.va;
        rkey    = qp->resp.rkey;
        resid   = qp->resp.resid;
@@ -680,9 +687,14 @@ static enum resp_states read_reply(struct rxe_qp *qp,
                res->read.va_org        = qp->resp.va;
 
                res->first_psn          = req_pkt->psn;
-               res->last_psn           = req_pkt->psn +
-                                         (reth_len(req_pkt) + mtu - 1) /
-                                         mtu - 1;
+
+               if (reth_len(req_pkt)) {
+                       res->last_psn   = (req_pkt->psn +
+                                          (reth_len(req_pkt) + mtu - 1) /
+                                          mtu - 1) & BTH_PSN_MASK;
+               } else {
+                       res->last_psn   = res->first_psn;
+               }
                res->cur_psn            = req_pkt->psn;
 
                res->read.resid         = qp->resp.resid;