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    SubjectRe: [PATCH] drivers/scsi: possible double spin_lock_irqsave
    Julia Lawall wrote:
    > From: Julia Lawall <julia@diku.dk>
    >
    > If both the test on rport and the call to get_device fail, then the lock is
    > already held. The re-lock is thus moved up into the two branches.
    >
    > On the other hand if kref_put should not be called with the lock held then
    > something else should be done.

    kref_put should not be called with the lock held. Updated patch below.

    Thanks,

    Brian

    --
    Brian King
    Linux on Power Virtualization
    IBM Linux Technology Center


    Fixes a potential deadlock in the ibmvfc driver in the rport
    add thread if it encounters an rport it wants to add which
    it cannot get a reference to.

    Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
    ---

    drivers/scsi/ibmvscsi/ibmvfc.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff -puN drivers/scsi/ibmvscsi/ibmvfc.c~ibmvfc_fix_add_locking drivers/scsi/ibmvscsi/ibmvfc.c
    --- linux-2.6/drivers/scsi/ibmvscsi/ibmvfc.c~ibmvfc_fix_add_locking 2009-07-20 09:49:28.000000000 -0500
    +++ linux-2.6-bjking1/drivers/scsi/ibmvscsi/ibmvfc.c 2009-07-20 09:54:54.000000000 -0500
    @@ -4283,7 +4283,8 @@ static void ibmvfc_rport_add_thread(stru
    tgt_dbg(tgt, "Setting rport roles\n");
    fc_remote_port_rolechg(rport, tgt->ids.roles);
    put_device(&rport->dev);
    - }
    + } else
    + spin_unlock_irqrestore(vhost->host->host_lock, flags);

    kref_put(&tgt->kref, ibmvfc_release_tgt);
    spin_lock_irqsave(vhost->host->host_lock, flags);
    _

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