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

[Steffen Maier]

On 04/13/2017 12:22 PM, Steffen Maier wrote:
> On 04/13/2017 04:01 AM, 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?
>
> Does this help somewhat?:
>
> https://www.redhat.com/archives/dm-devel/2015-December/msg00042.html
>
> As workaround for eppic scripts in crash, we currently re-define struct
> dm_table in eppic scripts, because "set scope dm_table_create" has not
> always worked as we liked. Sometimes "whatis dm_table_create" and again
> "set scope dm_table_create" worked and we put this in .crashrc, but
> eventually gave up and kept our struct re-define.

Before we wrote above posting, we tried this; maybe it helps in your case:

crash> set gdb on
gdb: on
gdb> ptype struct dm_table
type = struct dm_table {
     int undefined__;
}
gdb> ptype 'drivers/md/dm-table.c'::dm_table
No symbol "dm_table" in specified context.
gdb: gdb request failed: ptype 'drivers/md/dm-table.c'::dm_table
gdb> ptype struct dm_table
type = struct dm_table {
     uint64_t features;
     struct mapped_device *md;
     unsigned int type;
...

-- 
Mit freundlichen Grüßen / Kind regards
Steffen Maier

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