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    Subject[PATCH 3.16.y-ckt 165/183] IB/core: Fix deadlock on uverbs modify_qp error flow
    Date
    3.16.7-ckt8 -stable review patch.  If anyone has any objections, please let me know.

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

    From: Moshe Lazer <moshel@mellanox.com>

    commit 0fb8bcf022f19a375d7c4bd79ac513da8ae6d78b upstream.

    The deadlock occurs in __uverbs_modify_qp: we take a lock (idr_read_qp)
    and in case of failure in ib_resolve_eth_l2_attrs we don't release
    it (put_qp_read). Fix that.

    Fixes: ed4c54e5b4ba ("IB/core: Resolve Ethernet L2 addresses when modifying QP")
    Signed-off-by: Moshe Lazer <moshel@mellanox.com>
    Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
    Signed-off-by: Roland Dreier <roland@purestorage.com>
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    ---
    drivers/infiniband/core/uverbs_cmd.c | 9 +++++----
    1 file changed, 5 insertions(+), 4 deletions(-)

    diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
    index 23467a2abd62..2adc14372b94 100644
    --- a/drivers/infiniband/core/uverbs_cmd.c
    +++ b/drivers/infiniband/core/uverbs_cmd.c
    @@ -1964,20 +1964,21 @@ ssize_t ib_uverbs_modify_qp(struct ib_uverbs_file *file,
    if (qp->real_qp == qp) {
    ret = ib_resolve_eth_l2_attrs(qp, attr, &cmd.attr_mask);
    if (ret)
    - goto out;
    + goto release_qp;
    ret = qp->device->modify_qp(qp, attr,
    modify_qp_mask(qp->qp_type, cmd.attr_mask), &udata);
    } else {
    ret = ib_modify_qp(qp, attr, modify_qp_mask(qp->qp_type, cmd.attr_mask));
    }

    - put_qp_read(qp);
    -
    if (ret)
    - goto out;
    + goto release_qp;

    ret = in_len;

    +release_qp:
    + put_qp_read(qp);
    +
    out:
    kfree(attr);


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