[patch 02/13] git-scsi-misc gdth fix

[patch 02/13] git-scsi-misc gdth fix

[akpm]

From: James Bottomley <James.Bottomley@SteelEye.com>

On Sun, 2007-10-14 at 12:21 -0700, Andrew Morton wrote:
> On Sun, 14 Oct 2007 22:45:47 +0400 "Dave Milter" <davemilter@gmail.com> wrote:
>
> > I build linux-2.6.23-mm1 and try to boot it using qemu,
> > and it crashed with trace like this:
> > do_page_fault
> > error_code
> > lock_acquire
> > _spin_lock_irqsave
> > gdth_timeout
> > run_timer_softirq
> > __do_softirq
> > do_softirq
> >
> > I have screenshot, but have no idea, is it legal to include it, if I
> > sent copy to lkml.
> > config of kernel in attachment,
> > I apply all three patches from hot-fixes.
> >
>
> The screenshot is here:  http://userweb.kernel.org/~akpm/crash.png
>
> It would appear that gdth_timeout() is passing a bad pointer into
> spin_lock_irqsave().

There's a bug in the gdth rework in that the instance can be deleted
from the list before the actual timer is stopped.  This can be worked
around I think by the following patch; although we really should be
stopping the timer from firing when the list goes empty.


James said:

This is almost certainly the wrong fix for real hardware.  Although it
kills the timer when the list goes empty, nothing will ever restart it
when the list fills again.

Boaz, since you touched all of this, you get to fix it.  The correct fix
will be to control the timer along with the actual list instead of at
entry/exit time.  If you're not going to add this empty check to the
timer routine, make sure you use del_timer_sync() before removing the
last element from the list.


Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/scsi/gdth.c |    3 +++
 1 file changed, 3 insertions(+)

diff -puN drivers/scsi/gdth.c~git-scsi-misc-gdth-fix drivers/scsi/gdth.c
--- a/drivers/scsi/gdth.c~git-scsi-misc-gdth-fix
+++ a/drivers/scsi/gdth.c
@@ -3791,6 +3791,9 @@ static void gdth_timeout(ulong data)
     gdth_ha_str *ha;
     ulong flags;
 
+    if (list_empty(&gdth_instances))
+	return;
+
     ha = list_first_entry(&gdth_instances, gdth_ha_str, list);
     spin_lock_irqsave(&ha->smp_lock, flags);
 
_

Re: [patch 02/13] git-scsi-misc gdth fix

[Boaz Harrosh]

On Tue, Feb 05 2008 at 9:53 +0200, akpm@linux-foundation.org wrote:
> From: James Bottomley <James.Bottomley@SteelEye.com>
> 
> On Sun, 2007-10-14 at 12:21 -0700, Andrew Morton wrote:
>> On Sun, 14 Oct 2007 22:45:47 +0400 "Dave Milter" <davemilter@gmail.com> wrote:
>>
>>> I build linux-2.6.23-mm1 and try to boot it using qemu,
>>> and it crashed with trace like this:
>>> do_page_fault
>>> error_code
>>> lock_acquire
>>> _spin_lock_irqsave
>>> gdth_timeout
>>> run_timer_softirq
>>> __do_softirq
>>> do_softirq
>>>
>>> I have screenshot, but have no idea, is it legal to include it, if I
>>> sent copy to lkml.
>>> config of kernel in attachment,
>>> I apply all three patches from hot-fixes.
>>>
>> The screenshot is here:  http://userweb.kernel.org/~akpm/crash.png
>>
>> It would appear that gdth_timeout() is passing a bad pointer into
>> spin_lock_irqsave().
> 
> There's a bug in the gdth rework in that the instance can be deleted
> from the list before the actual timer is stopped.  This can be worked
> around I think by the following patch; although we really should be
> stopping the timer from firing when the list goes empty.
> 
> 
> James said:
> 
> This is almost certainly the wrong fix for real hardware.  Although it
> kills the timer when the list goes empty, nothing will ever restart it
> when the list fills again.
> 
> Boaz, since you touched all of this, you get to fix it.  The correct fix
> will be to control the timer along with the actual list instead of at
> entry/exit time.  If you're not going to add this empty check to the
> timer routine, make sure you use del_timer_sync() before removing the
> last element from the list.
> 
> 
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  drivers/scsi/gdth.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff -puN drivers/scsi/gdth.c~git-scsi-misc-gdth-fix drivers/scsi/gdth.c
> --- a/drivers/scsi/gdth.c~git-scsi-misc-gdth-fix
> +++ a/drivers/scsi/gdth.c
> @@ -3791,6 +3791,9 @@ static void gdth_timeout(ulong data)
>      gdth_ha_str *ha;
>      ulong flags;
>  
> +    if (list_empty(&gdth_instances))
> +	return;
> +
>      ha = list_first_entry(&gdth_instances, gdth_ha_str, list);
>      spin_lock_irqsave(&ha->smp_lock, flags);
>  
> _
Hello dear Andrew

Do you perhaps remember who as reported this problem, and if he can
test patches?

Boaz

---
gdth: Try to fix the Timer at exit problem

Remove_sync the timer before we delete the cards.

Testing-patches: Boaz Harrosh <bharrosh@panasas.com>

---
git-diff --stat -p v2.6.24
 drivers/scsi/gdth.c |   19 ++++++++++++-------
 1 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/gdth.c b/drivers/scsi/gdth.c
index b253b8c..57fa756 100644
--- a/drivers/scsi/gdth.c
+++ b/drivers/scsi/gdth.c
@@ -5102,6 +5105,9 @@ static int __init gdth_pci_probe_one(gdth_pci_str *pcistr, int ctr)
 	if (error)
 		goto out_free_coal_stat;
 	list_add_tail(&ha->list, &gdth_instances);
+
+	scsi_scan_host(shp);
+
 	return 0;
 
  out_free_coal_stat:
@@ -5137,8 +5143,6 @@ static void gdth_remove_one(gdth_ha_str *ha)
 		ha->sdev = NULL;
 	}
 
-	gdth_flush(ha);
-
 	if (shp->irq)
 		free_irq(shp->irq,ha);
 
@@ -5236,14 +5240,15 @@ static void __exit gdth_exit(void)
 {
 	gdth_ha_str *ha;
 
-	list_for_each_entry(ha, &gdth_instances, list)
-		gdth_remove_one(ha);
+	unregister_chrdev(major,"gdth");
+	unregister_reboot_notifier(&gdth_notifier);
 
 #ifdef GDTH_STATISTICS
-	del_timer(&gdth_timer);
+	del_timer_sync(&gdth_timer);
 #endif
-	unregister_chrdev(major,"gdth");
-	unregister_reboot_notifier(&gdth_notifier);
+
+	list_for_each_entry(ha, &gdth_instances, list)
+		gdth_remove_one(ha);
 }
 
 module_init(gdth_init);

Re: [patch 02/13] git-scsi-misc gdth fix

[Andrew Morton]

On Tue, 12 Feb 2008 17:27:33 +0200
Boaz Harrosh <bharrosh@panasas.com> wrote:

> On Tue, Feb 05 2008 at 9:53 +0200, akpm@linux-foundation.org wrote:
> > From: James Bottomley <James.Bottomley@SteelEye.com>
> > 
> > On Sun, 2007-10-14 at 12:21 -0700, Andrew Morton wrote:
> >> On Sun, 14 Oct 2007 22:45:47 +0400 "Dave Milter" <davemilter@gmail.com> wrote:
> >>
> >>> I build linux-2.6.23-mm1 and try to boot it using qemu,
> >>> and it crashed with trace like this:
> >>> do_page_fault
> >>> error_code
> >>> lock_acquire
> >>> _spin_lock_irqsave
> >>> gdth_timeout
> >>> run_timer_softirq
> >>> __do_softirq
> >>> do_softirq
> >>>
> >>> I have screenshot, but have no idea, is it legal to include it, if I
> >>> sent copy to lkml.
> >>> config of kernel in attachment,
> >>> I apply all three patches from hot-fixes.
> >>>
> >> The screenshot is here:  http://userweb.kernel.org/~akpm/crash.png
> >>
> >> It would appear that gdth_timeout() is passing a bad pointer into
> >> spin_lock_irqsave().
> > 
> > There's a bug in the gdth rework in that the instance can be deleted
> > from the list before the actual timer is stopped.  This can be worked
> > around I think by the following patch; although we really should be
> > stopping the timer from firing when the list goes empty.
> > 
> > 
> > James said:
> > 
> > This is almost certainly the wrong fix for real hardware.  Although it
> > kills the timer when the list goes empty, nothing will ever restart it
> > when the list fills again.
> > 
> > Boaz, since you touched all of this, you get to fix it.  The correct fix
> > will be to control the timer along with the actual list instead of at
> > entry/exit time.  If you're not going to add this empty check to the
> > timer routine, make sure you use del_timer_sync() before removing the
> > last element from the list.
> > 
> > 
> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> > ---
> > 
> >  drivers/scsi/gdth.c |    3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff -puN drivers/scsi/gdth.c~git-scsi-misc-gdth-fix drivers/scsi/gdth.c
> > --- a/drivers/scsi/gdth.c~git-scsi-misc-gdth-fix
> > +++ a/drivers/scsi/gdth.c
> > @@ -3791,6 +3791,9 @@ static void gdth_timeout(ulong data)
> >      gdth_ha_str *ha;
> >      ulong flags;
> >  
> > +    if (list_empty(&gdth_instances))
> > +	return;
> > +
> >      ha = list_first_entry(&gdth_instances, gdth_ha_str, list);
> >      spin_lock_irqsave(&ha->smp_lock, flags);
> >  
> > _
> Hello dear Andrew
> 
> Do you perhaps remember who as reported this problem, and if he can
> test patches?
> 

It was Dave Milter, who has been cc'ed on all of this.

> and if he can test patches?

Don't know.  Dave, would it be a possibility?

Thanks.

> 
> ---
> gdth: Try to fix the Timer at exit problem
> 
> Remove_sync the timer before we delete the cards.
> 
> Testing-patches: Boaz Harrosh <bharrosh@panasas.com>
> 
> ---
> git-diff --stat -p v2.6.24
>  drivers/scsi/gdth.c |   19 ++++++++++++-------
>  1 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/scsi/gdth.c b/drivers/scsi/gdth.c
> index b253b8c..57fa756 100644
> --- a/drivers/scsi/gdth.c
> +++ b/drivers/scsi/gdth.c
> @@ -5102,6 +5105,9 @@ static int __init gdth_pci_probe_one(gdth_pci_str *pcistr, int ctr)
>  	if (error)
>  		goto out_free_coal_stat;
>  	list_add_tail(&ha->list, &gdth_instances);
> +
> +	scsi_scan_host(shp);
> +
>  	return 0;
>  
>   out_free_coal_stat:
> @@ -5137,8 +5143,6 @@ static void gdth_remove_one(gdth_ha_str *ha)
>  		ha->sdev = NULL;
>  	}
>  
> -	gdth_flush(ha);
> -
>  	if (shp->irq)
>  		free_irq(shp->irq,ha);
>  
> @@ -5236,14 +5240,15 @@ static void __exit gdth_exit(void)
>  {
>  	gdth_ha_str *ha;
>  
> -	list_for_each_entry(ha, &gdth_instances, list)
> -		gdth_remove_one(ha);
> +	unregister_chrdev(major,"gdth");
> +	unregister_reboot_notifier(&gdth_notifier);
>  
>  #ifdef GDTH_STATISTICS
> -	del_timer(&gdth_timer);
> +	del_timer_sync(&gdth_timer);
>  #endif
> -	unregister_chrdev(major,"gdth");
> -	unregister_reboot_notifier(&gdth_notifier);
> +
> +	list_for_each_entry(ha, &gdth_instances, list)
> +		gdth_remove_one(ha);
>  }
>  
>  module_init(gdth_init);
> 
> 
> 
>