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    Subject[PATCH 5.15 049/148] net: mana: Add rmb after checking owner bits
    Date
    From: Haiyang Zhang <haiyangz@microsoft.com>

    commit 6fd2c68da55c552f86e401ebe40c4a619025ef69 upstream.

    Per GDMA spec, rmb is necessary after checking owner_bits, before
    reading EQ or CQ entries.

    Add rmb in these two places to comply with the specs.

    Cc: stable@vger.kernel.org
    Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)")
    Reported-by: Sinan Kaya <Sinan.Kaya@microsoft.com>
    Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
    Reviewed-by: Dexuan Cui <decui@microsoft.com>
    Link: https://lore.kernel.org/r/1662928805-15861-1-git-send-email-haiyangz@microsoft.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/net/ethernet/microsoft/mana/gdma_main.c | 10 ++++++++++
    1 file changed, 10 insertions(+)

    --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
    +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
    @@ -368,6 +368,11 @@ static void mana_gd_process_eq_events(vo
    break;
    }

    + /* Per GDMA spec, rmb is necessary after checking owner_bits, before
    + * reading eqe.
    + */
    + rmb();
    +
    mana_gd_process_eqe(eq);

    eq->head++;
    @@ -1096,6 +1101,11 @@ static int mana_gd_read_cqe(struct gdma_
    if (WARN_ON_ONCE(owner_bits != new_bits))
    return -1;

    + /* Per GDMA spec, rmb is necessary after checking owner_bits, before
    + * reading completion info
    + */
    + rmb();
    +
    comp->wq_num = cqe->cqe_info.wq_num;
    comp->is_sq = cqe->cqe_info.is_sq;
    memcpy(comp->cqe_data, cqe->cqe_data, GDMA_COMP_DATA_SIZE);

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