Re: [PATCH, libgomp] Fix deadlock in acc_set_device_type (ping x3)

[Chung-Lin Tang <cltang at codesourcery dot com>]

Ping x3

On 2016/4/19 10:30 PM, Chung-Lin Tang wrote:
> Ping x2.
> 
> Hi Jakub,
> This patch is fairly straightforward, and solves a easily encountered
> deadlock. Please approve for trunk and gcc-6-branch.
> 
> Thanks,
> Chung-Lin
> 
> On 2016/4/16 03:39 PM, Chung-Lin Tang wrote:
>> Ping.
>>
>> On 2016/3/28 05:45 PM, Chung-Lin Tang wrote:
>>> Hi Jakub, there's a path for deadlock on acc_device_lock when going
>>> through the acc_set_device_type() OpenACC library function.
>>> Basically, the gomp_init_targets_once() function should not be
>>> called with that held. The attached patch moves it appropriately.
>>>
>>> Also in this patch, there are several cases in acc_* functions
>>> where gomp_init_targets_once() is guarded by a test of
>>> !cached_base_dev. Since that function already uses pthread_once() to
>>> call gomp_target_init(), and technically cached_base_dev
>>> is protected by acc_device_lock, the cleanest way should be to
>>> simply drop those "if(!cached_base_dev)" tests.
>>>
>>> Tested libgomp without regressions on an nvptx offloaded system,
>>> is this okay for trunk?
>>>
>>> Thanks,
>>> Chung-Lin
>>>
>>> 2016-03-28  Chung-Lin Tang  <cltang@codesourcery.com>
>>>
>>>         * oacc-init.c (acc_init): Remove !cached_base_dev condition on call to
>>>         gomp_init_targets_once().
>>>         (acc_set_device_type): Remove !cached_base_dev condition on call to
>>>         gomp_init_targets_once(), move call to before acc_device_lock acquire,
>>>         to avoid deadlock.
>>>         (acc_get_device_num): Remove !cached_base_dev condition on call to
>>>         gomp_init_targets_once().
>>>         (acc_set_device_num): Likewise.
>>>
>>
>