lkml.org 
[lkml]   [2014]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH 1/1] block: rework flush sequencing for blk-mq
    On Fri, Mar 14, 2014 at 02:25:19AM -0700, Christoph Hellwig wrote:
    > b) is a bit harder, but we should think hard about it when rewriting the
    > multipath code to support blk-mq. Talking about which I think trying to
    > use dm-multipath on any blk-mq device will go horribly crash and boom at
    > the moment.

    Talking abnout crashing and burning.. Hannes, did you run this patch
    past dm-devel and linux-scsi yet? Don't quite like it but the problem
    seems real..


    From: Hannes Reinecke <hare@suse.de>
    Subject: Kernel bug triggered in multipath
    References: bnc#486001
    Patch-mainline: not yet

    Starting multipath on a cciss device will cause a kernel
    warning to be triggered. Problem is that we're using the
    ->queuedata field of the request_queue to derefence the
    scsi device; however, for other (non-SCSI) devices this
    points to a totally different structure.
    So we should rather be using accessors here which make
    sure we're only returning valid SCSI device structures.

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

    ---
    drivers/scsi/device_handler/scsi_dh.c | 10 +++++-----
    drivers/scsi/scsi_lib.c | 11 +++++++++++
    include/scsi/scsi_device.h | 1 +
    3 files changed, 17 insertions(+), 5 deletions(-)

    --- a/drivers/scsi/device_handler/scsi_dh.c
    +++ b/drivers/scsi/device_handler/scsi_dh.c
    @@ -397,7 +397,7 @@ int scsi_dh_activate(struct request_queu
    struct device *dev = NULL;

    spin_lock_irqsave(q->queue_lock, flags);
    - sdev = q->queuedata;
    + sdev = scsi_device_from_queue(q);
    if (!sdev) {
    spin_unlock_irqrestore(q->queue_lock, flags);
    err = SCSI_DH_NOSYS;
    @@ -484,7 +484,7 @@ int scsi_dh_attach(struct request_queue
    return -EINVAL;

    spin_lock_irqsave(q->queue_lock, flags);
    - sdev = q->queuedata;
    + sdev = scsi_device_from_queue(q);
    if (!sdev || !get_device(&sdev->sdev_gendev))
    err = -ENODEV;
    spin_unlock_irqrestore(q->queue_lock, flags);
    @@ -512,7 +512,7 @@ void scsi_dh_detach(struct request_queue
    struct scsi_device_handler *scsi_dh = NULL;

    spin_lock_irqsave(q->queue_lock, flags);
    - sdev = q->queuedata;
    + sdev = scsi_device_from_queue(q);
    if (!sdev || !get_device(&sdev->sdev_gendev))
    sdev = NULL;
    spin_unlock_irqrestore(q->queue_lock, flags);
    --- a/drivers/scsi/scsi_lib.c
    +++ b/drivers/scsi/scsi_lib.c
    @@ -1594,6 +1594,17 @@ out:
    spin_lock_irq(q->queue_lock);
    }

    +struct scsi_device *scsi_device_from_queue(struct request_queue *q)
    +{
    + struct scsi_device *sdev = NULL;
    +
    + if (q->request_fn == scsi_request_fn)
    + sdev = q->queuedata;
    +
    + return sdev;
    +}
    +EXPORT_SYMBOL_GPL(scsi_device_from_queue);
    +
    u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
    {
    struct device *host_dev;
    --- a/include/scsi/scsi_device.h
    +++ b/include/scsi/scsi_device.h
    @@ -300,6 +300,7 @@ extern void starget_for_each_device(stru
    extern void __starget_for_each_device(struct scsi_target *, void *,
    void (*fn)(struct scsi_device *,
    void *));
    +extern struct scsi_device *scsi_device_from_queue(struct request_queue *);

    /* only exposed to implement shost_for_each_device */
    extern struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *,

    \
     
     \ /
      Last update: 2014-03-14 12:21    [W:2.321 / U:0.560 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site