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    Subject[PATCH] firewire: fw-sbp2: enforce read order of device generation and node ID
    Two fixes:
    - There was a small window where a login or reconnect job could use an
    already updated card generation with an outdated node ID. We better
    use the fw_device.generation here, not the fw_card.generation.
    - Insert a memory barrier to ensure that the device generation is read
    before the node ID. This is to guarantee that the generation is not
    newer than the node ID.

    A small optimization:
    - The target's and initiator's node IDs can be obtained from fw_device
    and fw_card. Dereferencing their underlying topology objects is not
    necessary.

    Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
    ---
    drivers/firewire/fw-sbp2.c | 14 ++++++++------
    1 file changed, 8 insertions(+), 6 deletions(-)

    Index: linux/drivers/firewire/fw-sbp2.c
    ===================================================================
    --- linux.orig/drivers/firewire/fw-sbp2.c
    +++ linux/drivers/firewire/fw-sbp2.c
    @@ -643,9 +643,10 @@ static void sbp2_login(struct work_struc
    struct sbp2_login_response response;
    int generation, node_id, local_node_id;

    - generation = device->card->generation;
    - node_id = device->node->node_id;
    - local_node_id = device->card->local_node->node_id;
    + generation = device->generation;
    + rmb();
    + node_id = device->node_id;
    + local_node_id = device->card->node_id;

    if (sbp2_send_management_orb(lu, node_id, generation,
    SBP2_LOGIN_REQUEST, lu->lun, &response) < 0) {
    @@ -900,9 +901,10 @@ static void sbp2_reconnect(struct work_s
    struct fw_device *device = fw_device(unit->device.parent);
    int generation, node_id, local_node_id;

    - generation = device->card->generation;
    - node_id = device->node->node_id;
    - local_node_id = device->card->local_node->node_id;
    + generation = device->generation;
    + rmb();
    + node_id = device->node_id;
    + local_node_id = device->card->node_id;

    if (sbp2_send_management_orb(lu, node_id, generation,
    SBP2_RECONNECT_REQUEST,
    --
    Stefan Richter
    -=====-=-=== =-== ----=
    http://arcgraph.de/sr/
    -
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