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 <h...@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 <h...@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 *,
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
