Re: Cell multi-arch broken (Re: [PATCH 2/2] GNU/Linux: Stop using libthread_db/td_ta_thr_iter)

[Doug Evans <xdje42@gmail.com>]

Doug Evans <xdje42@gmail.com> writes:
> "Ulrich Weigand" <uweigand@de.ibm.com> writes:
>> Ah, indeed that works for me.  The attached patch also fixes the
>> problem for me.
>>
>> Bye,
>> Ulrich
>>
>> Index: binutils-gdb/gdb/linux-thread-db.c
>> ===================================================================
>> --- binutils-gdb.orig/gdb/linux-thread-db.c
>> +++ binutils-gdb/gdb/linux-thread-db.c
>> @@ -1851,13 +1851,16 @@ thread_db_get_thread_local_address (stru
>>    struct thread_info *thread_info;
>>    struct target_ops *beneath;
>>  
>> -  /* If we have not discovered any threads yet, check now.  */
>> -  if (!have_threads (ptid))
>> -    thread_db_find_new_threads_1 (ptid);
>> -
>>    /* Find the matching thread.  */
>>    thread_info = find_thread_ptid (ptid);
>>  
>> +  /* We may not have discovered the thread yet.  */
>> +  if (thread_info != NULL && thread_info->priv == NULL)
>> +    {
>> +      thread_from_lwp (ptid);
>> +      thread_info = find_thread_ptid (ptid);
>> +    }
>> +
>>    if (thread_info != NULL && thread_info->priv != NULL)
>>      {
>>        td_err_e err;
>
> Hi.
>
> Just a thought.
>
> It's kinda clumsy that thread_from_lwp ends with this:
>
>   /* Fill the cache.  */
>   tp = find_thread_ptid (ptid);
>   record_thread (info, tp, ptid, &th, &ti);
>
> and then we just call find_thread_ptid again after it returns:
>
>> +      thread_from_lwp (ptid);
>> +      thread_info = find_thread_ptid (ptid);
>
> One might ask "Why doesn't thread_from_lwp just return thread_info?"
>
> From record_thread things seem to be a be more subtle.
> Even if we pass in a non-NULL TP we may still create a new one.
>
>   /* Add the thread to GDB's thread list.  If we already know about a
>      thread with this PTID, but it's marked exited, then the kernel
>      reused the tid of an old thread.  */
>   if (tp == NULL || tp->state == THREAD_EXITED)
>     tp = add_thread_with_info (ptid, priv);
>   else
>     tp->priv = priv;
>
> So it'd be helpful if record_thread also returned tp.
> Sound about right?
>
> 2015-08-27  Doug Evans  <xdje42@gmail.com>
>
> 	* linux-thread-db.c (record_thread): Return the created thread.
> 	(thread_from_lwp): Likewise.
> 	(thread_db_get_thread_local_address): Update.

Committed.