Ping x2.
On 2015/9/9 04:08 PM, Chung-Lin Tang wrote:
> Ping.
>
> On 2015/8/27 09:44 PM, Chung-Lin Tang wrote:
>> We've discovered that, for several of the libgomp plugin interface routines,
>> if the target specific routine calls exit() (usually upon a fatal condition),
>> deadlock ensues. We found this using nvptx, but it's possible on intelmic as
>> well.
>>
>> This is due to many of the plugin routines are called with the device lock
>> held,
>> and when exit() is called inside the plugin code, the GOMP_unregister_var()
>> destructor
>> tries to iterate through and acquire all device locks to cleanup. Since we
>> already hold
>> one of the device locks, this just gets stuck. Also because gomp_mutex_t is
>> a
>> simple futex based lock implementation (instead of pthreads), we don't have a
>> trylock mechanism to use either.
>>
>> So this patch tries to alleviate this problem by changing the plugin
>> interface;
>> the plugin routines that are called while holding the device lock are
>> adjusted
>> to assume to never fatal exit, but return a value back to libgomp proper to
>> indicate execution results. The core libgomp code then may unlock and call
>> gomp_fatal().
>>
>> We believe this is the right route to solve the problem, since there's only
>> two accel target plugins so far. Besides the nvptx plugin, I have made some
>> effort
>> to update the intelmic plugin as well, though it's not as thoroughly audited.
>> Intel folks might want to further make sure your plugin code is free of this
>> problem as well.
>>
>> This patch contains the libgomp proper changes. The nvptx and intelmic
>> patches follow.
>> I have tested the libgomp testsuite without regressions for both accel
>> targets, is this
>> okay for trunk?
>>
>> Thanks,
>> Chung-Lin
>>
>> 2015-08-27 Chung-Lin Tang <clt...@codesourcery.com>
>>
>> * oacc-host.c (host_init_device): Change return type to bool.
>> (host_fini_device): Likewise.
>> (host_dev2host): Likewise.
>> (host_host2dev): Likewise.
>> (host_free): Likewise.
>> (host_alloc): Change return type to bool, change to use out
>> parameter to return allocated pointer.
>> * oacc-mem.c (acc_malloc): Adjust plugin hook declaration change,
>> handle fatal error.
>> (acc_free): Likewise.
>> (acc_memcpy_to_device): Likewise.
>> (acc_memcpy_from_device): Likewise.
>> * oacc-init.c (acc_init_1): Handle gomp_init_device return code,
>> handle fatal error.
>> (acc_set_device_type): Likewise.
>> (acc_set_device_num): Likewise.
>> * target.c (gomp_map_vars): Adjust alloc_func plugin hook call,
>> add device unlock, handle fatal error.
>> (gomp_unmap_tgt): Change return type to bool, adjust free_func
>> plugin call.
>> (gomp_copy_from_async): Handle dev2host_func return code, handle
>> fatal error.
>> (gomp_unmap_vars): Likewise.
>> (gomp_init_device): Change return type to bool, adjust call to
>> init_device_func plugin hook.
>> (GOMP_target): Adjust call to gomp_init_device, handle fatal error.
>> (GOMP_target_data): Likewise.
>> (GOMP_target_update): Likewise.
>> * libgomp.h (gomp_device_descr.init_device_func): Change return
>> type to bool.
>> (gomp_device_descr.fini_device_func): Likewise.
>> (gomp_device_descr.free_func): Likewise.
>> (gomp_device_descr.dev2host_func): Likewise.
>> (gomp_device_descr.host2dev_func) Likewise.
>> (gomp_device_descr.alloc_func): Change return
>> type to bool, use out parameter to return pointer.
>> (gomp_init_device): Change return
>> type to bool.
>>
>
