[Mesa-dev] [PATCH] llvmpipe: Check thread creation errors

[Nathan Kidd]

Thanks.  I'll have to rely on someone with a commit bit to push this.

On 2019-11-10 4:55 p.m., Roland Scheidegger wrote:
> Looks great to me.
> Reviewed-by: Roland Scheidegger <sroland at vmware.com>
> 
> Am 08.11.19 um 23:05 schrieb Nathan Kidd:
>> In the case of glibc, pthread_t is internally a pointer.  If
>> lp_rast_destroy() passes a 0-value pthread_t to pthread_join(), the
>> latter will SEGV dereferencing it.
>>
>> pthread_create() can fail if either the user's ulimit -u or Linux
>> kernel's /proc/sys/kernel/threads-max is reached.
>>
>> Choosing to continue, rather than fail, on theory that it is better to
>> run with the one main thread, than not run at all.
>>
>> Keeping as many threads as we got, since lack of threads severely
>> degrades llvmpipe performance.
>>
>> Signed-off-by: Nathan Kidd <nkidd at opentext.com>
>> ---
>>  src/gallium/drivers/llvmpipe/lp_rast.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/src/gallium/drivers/llvmpipe/lp_rast.c
>> b/src/gallium/drivers/llvmpipe/lp_rast.c
>> index d50e92b..ef783ea 100644
>> --- a/src/gallium/drivers/llvmpipe/lp_rast.c
>> +++ b/src/gallium/drivers/llvmpipe/lp_rast.c
>> @@ -867,6 +867,10 @@ create_rast_threads(struct lp_rasterizer *rast)
>>        pipe_semaphore_init(&rast->tasks[i].work_done, 0);
>>        rast->threads[i] = u_thread_create(thread_function,
>>                                              (void *) &rast->tasks[i]);
>> +      if (!rast->threads[i]) {
>> +         rast->num_threads = i; /* previous thread is max */
>> +         break;
>> +      }
>>     }
>>  }
>>  -- 1.8.3.1
>>
>>
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> 
>