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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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