[dm-devel] [PATCH] Re: [Report] crash tool cannot resolve struct dm_table properly

[Eric Ren]

On 04/14/2017 05:53 AM, Mikulas Patocka wrote:
>
> On Thu, 13 Apr 2017, Eric Ren wrote:
>
>> Hi,
>>
>>
>> On 04/13/2017 07:28 PM, Mikulas Patocka wrote:
>>> On Thu, 13 Apr 2017, Eric Ren wrote:
>>>
>>>> Hi Mikulas,
>>>>
>>>> When inspecting on coredump with crash tool, I find that 'dm_table' cannot
>>>> be
>>>> resolved properly as follows:
>>>>
>>>> ===
>>>> crash> struct dm_table
>>>> struct dm_table {
>>>>       int undefined__;
>>>> }
>>>> SIZE: 4
>>>> ===
>>>>
>>>> Looks this issue is introduced by 83d5e5b (dm: optimize use SRCU and RCU)
>>>> with
>>>> this code:
>>>> ===
>>>> +/*
>>>> + * A dummy definition to make RCU happy.
>>>> + * struct dm_table should never be dereferenced in this file.
>>>>    + */ +struct dm_table {
>>>> + int undefined__;
>>>> +};
>>>> +
>>>> ===
>>>>
>>>> It stops me from looking into dm_table when analyzing coredump. Is there
>>>> any
>>>> workaround?
>>>> or can be fixed somehow?
>>>>
>>>> Regards,
>>>> Eric
>>> So, move dm_table definition to drivers/md/dm.h
>> Thanks. So, are your going to fix this? Or should I test on your suggestion
>> and send a patch if it works?
>>
>> Regards,
>> Eric
>>> Mikulas
>>>
> Hi
>
> It turned out that the RCU macros changed and the dummy definition is no
> longer needed. So, we can remove it.
Hi!

That's great, thanks!

Regards,
Eric
>
>
>
> From: Mikulas Patocka <mpatocka at redhat.com>
>
> dm: remove dummy dm_table definition
>
> This dummy structure definition was required for RCU macros, but it
> doesn't seem to be required anymore, so delete it.
>
> The dummy definition confuses the crash tool, see
> https://www.redhat.com/archives/dm-devel/2017-April/msg00197.html
>
> Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
>
> ---
>   drivers/md/dm-ioctl.c |    8 --------
>   1 file changed, 8 deletions(-)
>
> Index: linux-2.6/drivers/md/dm-ioctl.c
> ===================================================================
> --- linux-2.6.orig/drivers/md/dm-ioctl.c
> +++ linux-2.6/drivers/md/dm-ioctl.c
> @@ -37,14 +37,6 @@ struct hash_cell {
>   	struct dm_table *new_map;
>   };
>   
> -/*
> - * A dummy definition to make RCU happy.
> - * struct dm_table should never be dereferenced in this file.
> - */
> -struct dm_table {
> -	int undefined__;
> -};
> -
>   struct vers_iter {
>       size_t param_size;
>       struct dm_target_versions *vers, *old_vers;
>