Re: [PATCH] Warn users about mismatched PID namespaces

[Pedro Alves <palves@redhat.com>]

On 10/30/2014 12:51 PM, Daniel Colascione wrote:
> On 10/30/2014 12:49 PM, Pedro Alves wrote:
>> On 10/30/2014 12:32 PM, Daniel Colascione wrote:
>>> On 10/30/2014 12:23 PM, Pedro Alves wrote:
>>>> On 10/30/2014 03:07 AM, Daniel Colascione wrote:
>>>>
>>>>> diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
>>>>> index 352fac1..4089417 100644
>>>>> - --- a/gdb/linux-thread-db.c
>>>>> +++ b/gdb/linux-thread-db.c
>>>>> @@ -1223,6 +1223,25 @@ thread_db_new_objfile (struct objfile *objfile)
>>>>>  static void
>>>>>  thread_db_inferior_created (struct target_ops *target, int from_tty)
>>>>>  {
>>>>> +  /* If the child is in a different PID namespace, its idea of its PID
>>>>> +     will differ from our idea of its PID.  When we scan the child's
>>>>> +     thread list, we'll mistakenly think it has no threads since the
>>>>> +     thread PID fields won't match the PID we give to
>>>>> +     libthread_db.  */
>>>>
>>>> Why not give libthread_db the right PID then?
>>>
>>> How do you suggest find it? 
>>
>> Isn't it visible somewhere in /proc ?
> 
> Not AFAICT, but maybe I overlooked something.

Oh well...  Fine with me to add a warning then.  I'd appreciate
that the comment in the code mentioned that that's no way to
retrieve the right PID.  I see a couple minor formatting issues in
the patch, but nothing major.  Do you have your copyright assignment
for GDB on file?  Seems you're only covered for emacs atm,
unfortunately.

> 
>>
>>> There's some talk on LKML of adding the necessary system call, but it's not in-tree yet.
>>
>> Do you have a url handy?
> 
> https://lwn.net/Articles/602987/

Thanks.

Thanks,
Pedro Alves