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    SubjectRe: [PATCH 14/14] fnic: reject device resets without assigned tags for the blk-mq case
    On 06/25/2014 06:52 PM, Christoph Hellwig wrote:
    > Current the midlayer fakes up a struct request for the explicit reset
    > ioctls, and those don't have a tag allocated to them. The fnic driver pokes
    > into midlayer structures to paper over this design issue, but that won't
    > work for the blk-mq case.
    >
    > Either someone who can actually test the hardware will have to come up with
    > a similar hack for the blk-mq case, or we'll have to bite the bullet and fix
    > the way the EH ioctls work for real, but until that happens we fail these
    > explicit requests here.
    >
    > Signed-off-by: Christoph Hellwig <hch@lst.de>
    > Cc: Hiral Patel <hiralpat@cisco.com>
    > Cc: Suma Ramars <sramars@cisco.com>
    > Cc: Brian Uchino <buchino@cisco.com>
    > ---
    > drivers/scsi/fnic/fnic_scsi.c | 16 ++++++++++++++++
    > 1 file changed, 16 insertions(+)
    >
    > diff --git a/drivers/scsi/fnic/fnic_scsi.c b/drivers/scsi/fnic/fnic_scsi.c
    > index 3f88f56..961bdf5 100644
    > --- a/drivers/scsi/fnic/fnic_scsi.c
    > +++ b/drivers/scsi/fnic/fnic_scsi.c
    > @@ -2224,6 +2224,22 @@ int fnic_device_reset(struct scsi_cmnd *sc)
    >
    > tag = sc->request->tag;
    > if (unlikely(tag < 0)) {
    > + /*
    > + * XXX(hch): current the midlayer fakes up a struct
    > + * request for the explicit reset ioctls, and those
    > + * don't have a tag allocated to them. The below
    > + * code pokes into midlayer structures to paper over
    > + * this design issue, but that won't work for blk-mq.
    > + *
    > + * Either someone who can actually test the hardware
    > + * will have to come up with a similar hack for the
    > + * blk-mq case, or we'll have to bite the bullet and
    > + * fix the way the EH ioctls work for real, but until
    > + * that happens we fail these explicit requests here.
    > + */
    > + if (shost_use_blk_mq(sc->device->host))
    > + goto fnic_device_reset_end;
    > +
    > tag = fnic_scsi_host_start_tag(fnic, sc);
    > if (unlikely(tag == SCSI_NO_TAG))
    > goto fnic_device_reset_end;
    >
    The correct fix will be part of my EH redesign.
    Plan is to allocate a real command/request for EH, which then can be
    used to send down EH TMFs and related commands.

    Reviewed-by: Hannes Reinecke <hare@suse.de>

    Cheers,

    Hannes
    --
    Dr. Hannes Reinecke zSeries & Storage
    hare@suse.de +49 911 74053 688
    SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
    GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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