RDMA/cxgb4: Fix overflow bug in CQ arm

- wrap cq->cqidx_inc based on cq size.
- optimize t4_arm_cq logic.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 12 insertions, 19 deletions

diff --git a/drivers/infiniband/hw/cxgb4/t4.h b/drivers/infiniband/hw/cxgb4/t4.h
index 712bc5620d3e..333abd3c7264 100644
--- a/drivers/infiniband/hw/cxgb4/t4.h
+++ b/drivers/infiniband/hw/cxgb4/t4.h
@@ -449,25 +449,17 @@ struct t4_cq {
 static inline int t4_arm_cq(struct t4_cq *cq, int se)
 {
         u32 val;
-        u16 inc;
-
-        do {
-                /*
-                 * inc must be less the both the max update value -and-
-                 * the size of the CQ.
-                 */
-                inc = cq->cidx_inc <= CIDXINC_MASK ? cq->cidx_inc :
-                                                     CIDXINC_MASK;
-                inc = inc <= (cq->size - 1) ? inc : (cq->size - 1);
-                if (inc == cq->cidx_inc)
-                        val = SEINTARM(se) | CIDXINC(inc) | TIMERREG(6) |
-                              INGRESSQID(cq->cqid);
-                else
-                        val = SEINTARM(0) | CIDXINC(inc) | TIMERREG(7) |
-                              INGRESSQID(cq->cqid);
-                cq->cidx_inc -= inc;
+
+        while (cq->cidx_inc > CIDXINC_MASK) {
+                val = SEINTARM(0) | CIDXINC(CIDXINC_MASK) | TIMERREG(7) |
+                      INGRESSQID(cq->cqid);
                 writel(val, cq->gts);
-        } while (cq->cidx_inc);
+                cq->cidx_inc -= CIDXINC_MASK;
+        }
+        val = SEINTARM(se) | CIDXINC(cq->cidx_inc) | TIMERREG(6) |
+              INGRESSQID(cq->cqid);
+        writel(val, cq->gts);
+        cq->cidx_inc = 0;
         return 0;
 }
 
@@ -488,7 +480,8 @@ static inline void t4_swcq_consume(struct t4_cq *cq)
 static inline void t4_hwcq_consume(struct t4_cq *cq)
 {
         cq->bits_type_ts = cq->queue[cq->cidx].bits_type_ts;
-        cq->cidx_inc++;
+        if (++cq->cidx_inc == cq->size)
+                cq->cidx_inc = 0;
         if (++cq->cidx == cq->size) {
                 cq->cidx = 0;
                 cq->gen ^= 1;