Re: [Intel-gfx] [PATCH i-g-t 3/6] igt/core: Fix build warning

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 19/11/2021 13:53, Petri Latvala wrote:
> On Fri, Nov 19, 2021 at 12:59:42PM +0000, Tvrtko Ursulin wrote:
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> .../lib/igt_thread.c: In function ‘__igt_unique____igt_constructor_l66’:
>> .../lib/igt_thread.c:68:9: warning: ‘pthread_setspecific’ expecting 1 byte in a region of size 0 [-Wstringop-overread]
>>     68 |         pthread_setspecific(__igt_is_main_thread, (void*) 0x1);
>>        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> Cc: Petri Latvala <petri.latvala@intel.com>
>> ---
>>   lib/igt_core.c   | 6 ++++--
>>   lib/igt_thread.c | 4 +++-
>>   2 files changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/igt_core.c b/lib/igt_core.c
>> index ec05535cd56e..acb9743c4a24 100644
>> --- a/lib/igt_core.c
>> +++ b/lib/igt_core.c
>> @@ -2752,6 +2752,8 @@ void igt_vlog(const char *domain, enum igt_log_level level, const char *format,
>>   	char *line, *formatted_line;
>>   	char *thread_id;
>>   	const char *program_name;
>> +	const uintptr_t false_key = 0;
>> +	const uintptr_t true_key = 1;
>>   	const char *igt_log_level_str[] = {
>>   		"DEBUG",
>>   		"INFO",
>> @@ -2796,9 +2798,9 @@ void igt_vlog(const char *domain, enum igt_log_level level, const char *format,
>>   	}
>>   
>>   	if (line[strlen(line) - 1] == '\n')
>> -		pthread_setspecific(__vlog_line_continuation, (void*) false);
>> +		pthread_setspecific(__vlog_line_continuation, &false_key);
>>   	else
>> -		pthread_setspecific(__vlog_line_continuation, (void*) true);
>> +		pthread_setspecific(__vlog_line_continuation, &true_key);
> 
> Quoting the usage of this:
>          if (pthread_getspecific(__vlog_line_continuation)) {
> 
> That's going to give a non-null pointer in both cases.

Doh..

> 
> 
> 
>>   
>>   	/* append log buffer */
>>   	_igt_log_buffer_append(formatted_line);
>> diff --git a/lib/igt_thread.c b/lib/igt_thread.c
>> index 5bdda4102def..f5de2d57eaaa 100644
>> --- a/lib/igt_thread.c
>> +++ b/lib/igt_thread.c
>> @@ -64,6 +64,8 @@ bool igt_thread_is_main(void)
>>   }
>>   
>>   igt_constructor {
>> +	const uintptr_t key = 1;
>> +
>>   	pthread_key_create(&__igt_is_main_thread, NULL);
>> -	pthread_setspecific(__igt_is_main_thread, (void*) 0x1);
>> +	pthread_setspecific(__igt_is_main_thread, &key);
> 
> This is fine, __igt_is_main_thread key will have non-null only on the
> main thread. But still a bit sus slapping the address of a
> function-local variable to setspecific, we might just be trading a
> compiler warning for a new future one.

And this is then the same - why do you say this one is okay? :)

Okay I wasn't sufficiently focused while trying to fix this. No idea 
then apart for playing with pragmas.

Regards,

Tvrtko