Re: [PATCH] cciss: Ignore stale commands after reboot

Hannes Reinecke
2009-07-02T09:37:18Z

Jens Axboe wrote:
> On Thu, Jul 02 2009, Hannes Reinecke wrote:
>> Jens Axboe wrote:
>>> On Thu, Jul 02 2009, Hannes Reinecke wrote:
>>>> When doing an unexpected shutdown like kexec the cciss
>>>> firmware might still have some commands in flight, which
>>>> it is trying to complete.
>>>> The driver is doing it's best on resetting the HBA,
>>>> but sadly there's a firmware issue causing the firmware
>>>> _not_ to abort or drop old commands.
>>>> So the firmware will send us commands which we haven't
>>>> accounted for, causing the driver to panic.
>>>>
>>>> With this patch we're just ignoring these commands as
>>>> there is nothing we could be doing with them anyway.
>>>>
>>>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>>>> ---
>>>> drivers/block/cciss.c | 14 ++++++++++++--
>>>> drivers/block/cciss_cmd.h | 1 +
>>>> 2 files changed, 13 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
>>>> index c7a527c..8dd4c0d 100644
>>>> --- a/drivers/block/cciss.c
>>>> +++ b/drivers/block/cciss.c
>>>> @@ -226,7 +226,16 @@ static inline void addQ(struct hlist_head *list, CommandList_struct *c)
>>>>
>>>> static inline void removeQ(CommandList_struct *c)
>>>> {
>>>> - if (WARN_ON(hlist_unhashed(&c->list)))
>>>> + /*
>>>> + * After kexec/dump some commands might still
>>>> + * be in flight, which the firmware will try
>>>> + * to complete. Resetting the firmware doesn't work
>>>> + * with old fw revisions, so we have to mark
>>>> + * them off as 'stale' to prevent the driver from
>>>> + * falling over.
>>>> + */
>>>> + if (unlikely(hlist_unhashed(&c->list))) {
>>>> + c->cmd_type = CMD_MSG_STALE;
>>>> return;
>>>>
>>>> hlist_del_init(&c->list);
>>> Ehm, that looks rather dangerous. What's the level of testing this patch
>>> received?
>>>
>> Where is the danger here?
>
> The danger is that the patch doesn't even compile :-)
> At least it had the { at the end of the if, otherwise it would have been
> insta-hang.
>
Bah. Should've said so.
That's what you get when you cut-n-paste from a different version.

OK, resending.

Cheers,

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