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

Jens Axboe
2009-07-02T08:28:19Z

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?

--
Jens Axboe