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Subject[git patch review 5/7] [IB] mthca: fix wraparound handling in mthca_cq_clean()
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Handle case where prod_index has wrapped around and become less than
cq->cons_index by checking that their difference as a signed int is
positive rather than comparing directly.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

---
drivers/infiniband/hw/mthca/mthca_cq.c | 16 ++++++----------
1 files changed, 6 insertions(+), 10 deletions(-)
applies-to: 704990abeb22a51ed2722e92536d22135f60957f
64044bcf75063cb5a6d42712886a712449df2ce3
diff --git a/drivers/infiniband/hw/mthca/mthca_cq.c b/drivers/infiniband/hw/mthca/mthca_cq.c
index f98e235..4a8adce 100644
--- a/drivers/infiniband/hw/mthca/mthca_cq.c
+++ b/drivers/infiniband/hw/mthca/mthca_cq.c
@@ -258,7 +258,7 @@ void mthca_cq_clean(struct mthca_dev *de
{
struct mthca_cq *cq;
struct mthca_cqe *cqe;
- int prod_index;
+ u32 prod_index;
int nfreed = 0;

spin_lock_irq(&dev->cq_table.lock);
@@ -293,19 +293,15 @@ void mthca_cq_clean(struct mthca_dev *de
* Now sweep backwards through the CQ, removing CQ entries
* that match our QP by copying older entries on top of them.
*/
- while (prod_index > cq->cons_index) {
- cqe = get_cqe(cq, (prod_index - 1) & cq->ibcq.cqe);
+ while ((int) --prod_index - (int) cq->cons_index >= 0) {
+ cqe = get_cqe(cq, prod_index & cq->ibcq.cqe);
if (cqe->my_qpn == cpu_to_be32(qpn)) {
if (srq)
mthca_free_srq_wqe(srq, be32_to_cpu(cqe->wqe));
++nfreed;
- }
- else if (nfreed)
- memcpy(get_cqe(cq, (prod_index - 1 + nfreed) &
- cq->ibcq.cqe),
- cqe,
- MTHCA_CQ_ENTRY_SIZE);
- --prod_index;
+ } else if (nfreed)
+ memcpy(get_cqe(cq, (prod_index + nfreed) & cq->ibcq.cqe),
+ cqe, MTHCA_CQ_ENTRY_SIZE);
}

if (nfreed) {
---
0.99.9e
-
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