Re: [PATCH] Fix sporadic XFAILs in, gdb.threads/attach-many-short-lived-threads.exp

[Thiago Jung Bauermann <thiago.bauermann@linaro.org>]

Hello again,

Sorry, one more comment that occurred to me today.

Thiago Jung Bauermann <thiago.bauermann@linaro.org> writes:

> Bernd Edlinger <bernd.edlinger@hotmail.de> writes:
>
>> diff --git a/gdb/nat/linux-procfs.c b/gdb/nat/linux-procfs.c
>> index e2086952ce6..36e0f5bf16a 100644
>> --- a/gdb/nat/linux-procfs.c
>> +++ b/gdb/nat/linux-procfs.c
>> @@ -165,6 +165,9 @@ linux_proc_pid_is_gone (pid_t pid)
>>      }
>>    else if (have_state == 0)
>>      {
>> +      /* errno is ESRCH "No such process": assume thread has disappeared.  */
>> +      if (errno == ESRCH)
>> +	return 1;
>>        /* No "State:" line, assume thread is alive.  */
>>        return 0;
>>      }
>
> With this patch applied on top of my patch series fixing attach to
> zombie threads¹, I don't see these XFAILs anymore on an aarch64-linux
> machine where previously I saw them on every run of this testcase. Nice!
>
> I would even suggest removing the XFAIL from the testcase, if other
> people can confirm similar results.
>
> In any case:
>
> Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>

Actually, thinking more about it I think it would be better if
linux_proc_pid_get_state checked for errno == ESRCH itself and returned
-1 in that case (and also warn if that parameter is true), instead of
making its caller do that check.

The function documentation says:

/* Fill in STATE, a buffer with BUFFER_SIZE bytes with the 'State'
   line of /proc/PID/status.  Returns -1 on failure to open the /proc
   file, 1 if the line is found, and 0 if not found.  If WARN, warn on
   failure to open the /proc file.  */

I think that getting the ESRCH error while reading is semantically
equivalent to failing to open the /proc file. Returning 0 when the line
wasn't found because of the ESRCH error adheres to the letter of that
comment but not to its spirit. :-)

--
Thiago