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    Subject[PATCH AUTOSEL for 4.4 135/162] ntb_transport: Fix bug with max_mw_size parameter
    Date
    From: Logan Gunthorpe <logang@deltatee.com>

    [ Upstream commit cbd27448faff4843ac4b66cc71445a10623ff48d ]

    When using the max_mw_size parameter of ntb_transport to limit the size of
    the Memory windows, communication cannot be established and the queues
    freeze.

    This is because the mw_size that's reported to the peer is correctly
    limited but the size used locally is not. So the MW is initialized
    with a buffer smaller than the window but the TX side is using the
    full window. This means the TX side will be writing to a region of the
    window that points nowhere.

    This is easily fixed by applying the same limit to tx_size in
    ntb_transport_init_queue().

    Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
    Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
    Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>
    Cc: Dave Jiang <dave.jiang@intel.com>
    Signed-off-by: Jon Mason <jdmason@kudzu.us>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    ---
    drivers/ntb/ntb_transport.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
    index 3bbdf60f8908..49f3fba75f4d 100644
    --- a/drivers/ntb/ntb_transport.c
    +++ b/drivers/ntb/ntb_transport.c
    @@ -955,6 +955,9 @@ static int ntb_transport_init_queue(struct ntb_transport_ctx *nt,
    mw_base = nt->mw_vec[mw_num].phys_addr;
    mw_size = nt->mw_vec[mw_num].phys_size;

    + if (max_mw_size && mw_size > max_mw_size)
    + mw_size = max_mw_size;
    +
    tx_size = (unsigned int)mw_size / num_qps_mw;
    qp_offset = tx_size * (qp_num / mw_count);

    --
    2.15.1
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