[Crash-utility] [PATH] crash: Fix "dev -d" for recent kernels

[Dave Anderson]

----- Original Message -----
> Hello Dave,
> 
> The following kernel commit changes the member "rq" to member
> "root_rl" in the request_queue structure:
> 
> commit a051661ca6d134c18599498b185b667859d4339b
> Author: Tejun Heo <tj at kernel.org>
> Date:   Tue Jun 26 15:05:44 2012 -0700
>     blkcg: implement per-blkg request allocation
> -       struct request_list     rq;
> +       struct request_list     root_rl;
> 
> This breaks the "dev -d" crash command:
> 
> crash> dev -d
> MAJOR GENDISK            NAME       REQUEST QUEUE      TOTAL ASYNC
>  SYNC   DRV
> dev: invalid structure member offset: request_queue_rq
>      FILE: dev.c  LINE: 3807  FUNCTION: get_diskio_1()
>   80116438: OFFSET_verify+96
>   800f55da: get_diskio_1+62
>   800f5c52: display_all_diskio+1318
>   8006ff1c: exec_command+972
> dev: invalid structure member offset: request_queue_rq
>      FILE: dev.c  LINE: 3807  FUNCTION: get_diskio_1()
> 
> The following fix just uses "root_rl" instead of "rq". Not completely sure, if
> this is sufficient.
> 
> With the fix on my s390 system I get:
> 
> crash> dev -d
> MAJOR GENDISK            NAME       REQUEST QUEUE      TOTAL ASYNC   SYNC   DRV
>    94 0x1ea144a8         dasda      0x1ebcc2b8             0     0      0     0
>     9 0x1e93d9c8         md0        0x1ebcb560             0     0      0     0
> ---

The patch works OK for me, and I suppose that there are simply no I/O's
in progress.

I wish that the authors of crash utility options would keep an eye on their
own patches, and that that this would have been caught earlier.  I'll also
remove those prepended "0x"'s from the addresses -- I'm surprised I let that
slip in when the patch was originally proposed.  (I'd actually forgotten that
the option even existed...) 

Thanks,
  Dave  

>  dev.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> --- a/dev.c
> +++ b/dev.c
> @@ -4050,7 +4050,11 @@ void diskio_init(void)
>  	MEMBER_OFFSET_INIT(request_list_count, "request_list", "count");
>  	MEMBER_OFFSET_INIT(request_queue_in_flight, "request_queue",
>  		"in_flight");
> -	MEMBER_OFFSET_INIT(request_queue_rq, "request_queue", "rq");
> +	if (MEMBER_EXISTS("request_queue", "rq"))
> +		MEMBER_OFFSET_INIT(request_queue_rq, "request_queue", "rq");
> +	else
> +		MEMBER_OFFSET_INIT(request_queue_rq,
> +				   "request_queue", "root_rl");
>  	MEMBER_OFFSET_INIT(subsys_private_klist_devices, "subsys_private",
>  		"klist_devices");
>  	MEMBER_OFFSET_INIT(subsystem_kset, "subsystem", "kset");
>