linux-kernel - Re: [PATCH v4 1/2] scsi: Add intermediate STARGET_REMOVE state to scsi_target

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Date:	Tue, 12 Apr 2016 21:01:53 +0800
From:	Xiong Zhou <jencce.kernel@...il.com>
To:	Johannes Thumshirn <jthumshirn@...e.de>
Cc:	"Martin K. Petersen" <martin.petersen@...cle.com>,
	"James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
	"Ewan D. Milne" <emilne@...hat.com>,
	Hannes Reinecke <hare@...e.de>,
	Christoph Hellwig <hch@...radead.org>,
	linux-scsi@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	stable@...r.kernel.org
Subject: Re: [PATCH v4 1/2] scsi: Add intermediate STARGET_REMOVE state to scsi_target_state

How about this?

drivers/scsi/scsi_scan: mark STARGET_REMOVE state before destroy

Signed-off-by: Xiong Zhou <jencce.kernel@...il.com>
---
 drivers/scsi/scsi_scan.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 27df7e7..21092e5 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -395,6 +395,8 @@ static void scsi_target_reap_ref_release(struct kref *kref)
  transport_remove_device(&starget->dev);
  device_del(&starget->dev);
  }
+
+ starget->state = STARGET_REMOVE;
  scsi_target_destroy(starget);
 }

@@ -465,6 +467,7 @@ static struct scsi_target
*scsi_alloc_target(struct device *parent,
  dev_printk(KERN_ERR, dev, "target allocation failed, error %d\n", error);
  /* don't want scsi_target_reap to do the final
  * put because it will be under the host lock */
+ starget->state = STARGET_REMOVE;
  scsi_target_destroy(starget);
  return NULL;
  }
-- 
1.8.3.1

On Tue, Apr 5, 2016 at 5:50 PM, Johannes Thumshirn <jthumshirn@...e.de> wrote:
> Add intermediate STARGET_REMOVE state to scsi_target_state to avoid
> running into the BUG_ON() in scsi_target_reap(). The STARGET_REMOVE
> state is only valid in the path from scsi_remove_target() to
> scsi_target_destroy() indicating this target is going to be removed.
>
> This re-fixes the problem introduced in commits
> bc3f02a795d3b4faa99d37390174be2a75d091bd  and
> 40998193560dab6c3ce8d25f4fa58a23e252ef38 in a more comprehensive way.
>
> Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
> Fixes: 40998193560dab6c3ce8d25f4fa58a23e252ef38
> Cc: stable@...r.kernel.org
> Reviewed-by: Ewan D. Milne <emilne@...hat.com>
> Reviewed-by: Hannes Reinecke <hare@...e.com>
> Reviewed-by: James Bottomley <jejb@...ux.vnet.ibm.com>
> ---
>  drivers/scsi/scsi_scan.c   | 2 ++
>  drivers/scsi/scsi_sysfs.c  | 2 ++
>  include/scsi/scsi_device.h | 1 +
>  3 files changed, 5 insertions(+)
>
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 6a82066..63b8bca 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -315,6 +315,8 @@ static void scsi_target_destroy(struct scsi_target *starget)
>         struct Scsi_Host *shost = dev_to_shost(dev->parent);
>         unsigned long flags;
>
> +       BUG_ON(starget->state != STARGET_REMOVE &&
> +              starget->state != STARGET_CREATED);
>         starget->state = STARGET_DEL;
>         transport_destroy_device(dev);
>         spin_lock_irqsave(shost->host_lock, flags);
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 00bc721..0df82e8 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -1279,11 +1279,13 @@ restart:
>         spin_lock_irqsave(shost->host_lock, flags);
>         list_for_each_entry(starget, &shost->__targets, siblings) {
>                 if (starget->state == STARGET_DEL ||
> +                   starget->state == STARGET_REMOVE ||
>                     starget == last_target)
>                         continue;
>                 if (starget->dev.parent == dev || &starget->dev == dev) {
>                         kref_get(&starget->reap_ref);
>                         last_target = starget;
> +                       starget->state = STARGET_REMOVE;
>                         spin_unlock_irqrestore(shost->host_lock, flags);
>                         __scsi_remove_target(starget);
>                         scsi_target_reap(starget);
> diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
> index f63a167..2bffaa6 100644
> --- a/include/scsi/scsi_device.h
> +++ b/include/scsi/scsi_device.h
> @@ -240,6 +240,7 @@ scmd_printk(const char *, const struct scsi_cmnd *, const char *, ...);
>  enum scsi_target_state {
>         STARGET_CREATED = 1,
>         STARGET_RUNNING,
> +       STARGET_REMOVE,
>         STARGET_DEL,
>  };
>
> --
> 1.8.5.6
>