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    Subject[PATCH 4.11 78/84] infiniband: hns: avoid gcc-7.0.1 warning for uninitialized data
    Date
    4.11-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Arnd Bergmann <arnd@arndb.de>

    commit 5b0ff9a00755d4d9c209033a77f1ed8f3186fe5c upstream.

    hns_roce_v1_cq_set_ci() calls roce_set_bit() on an uninitialized field,
    which will then change only a few of its bits, causing a warning with
    the latest gcc:

    infiniband/hw/hns/hns_roce_hw_v1.c: In function 'hns_roce_v1_cq_set_ci':
    infiniband/hw/hns/hns_roce_hw_v1.c:1854:23: error: 'doorbell[1]' is used uninitialized in this function [-Werror=uninitialized]
    roce_set_bit(doorbell[1], ROCEE_DB_OTHERS_H_ROCEE_DB_OTH_HW_SYNS_S, 1);

    The code is actually correct since we always set all bits of the
    port_vlan field, but gcc correctly points out that the first
    access does contain uninitialized data.

    This initializes the field to zero first before setting the
    individual bits.

    Fixes: 9a4435375cd1 ("IB/hns: Add driver files for hns RoCE driver")
    Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    Signed-off-by: Doug Ledford <dledford@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/infiniband/hw/hns/hns_roce_hw_v1.c | 1 +
    1 file changed, 1 insertion(+)

    --- a/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
    +++ b/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
    @@ -1851,6 +1851,7 @@ void hns_roce_v1_cq_set_ci(struct hns_ro
    u32 doorbell[2];

    doorbell[0] = cons_index & ((hr_cq->cq_depth << 1) - 1);
    + doorbell[1] = 0;
    roce_set_bit(doorbell[1], ROCEE_DB_OTHERS_H_ROCEE_DB_OTH_HW_SYNS_S, 1);
    roce_set_field(doorbell[1], ROCEE_DB_OTHERS_H_ROCEE_DB_OTH_CMD_M,
    ROCEE_DB_OTHERS_H_ROCEE_DB_OTH_CMD_S, 3);

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