Hi,
I have not fully tried to understand it, yet.
(A) Regarding the issue of stalling, see als Andrew's patch and the
discussion about it in
"[PATCH] libgomp: fix hang on fatal error",
https://gcc.gnu.org/pipermail/gcc-patches/2022-October/603616.html
and in particular Jakub's two replies.
(b) I think you want to remove this:
On 15.12.22 18:34, Thomas Schwinge wrote:
--- a/libgomp/plugin/plugin-nvptx.c
+++ b/libgomp/plugin/plugin-nvptx.c
@@ -1,3 +1,5 @@
+#pragma GCC optimize "O0"
+
/* Plugin for NVPTX execution.
(c)
If the libgomp plugin doesn't request special
'host_to_dev_cpy'/'dev_to_host_cpy' for 'gomp_target_rev', then standard
'gomp_copy_host2dev'/'gomp_copy_dev2host' are used, which use
'gomp_device_copy', which expects the device to be locked. (As can be
told by the unconditional 'gomp_mutex_unlock (&devicep->lock);' before
'gomp_fatal'.) However, in a number of the
'gomp_copy_host2dev'/'gomp_copy_dev2host' calls from 'gomp_target_rev',
the device definitely is not locked; see the calls adjacent to the TODO
The question is what unlocks the device – it is surely locked in
gomp_target_rev by:
if (!(devicep->capabilities & GOMP_OFFLOAD_CAP_SHARED_MEM))
...
gomp_mutex_lock (&devicep->lock);
for (uint64_t i = 0; i < mapnum; i++)
...
}
gomp_mutex_unlock (&devicep->lock);
}
Except for code like:
gomp_mutex_unlock (&devicep->lock);
gomp_fatal ("gomp_target_rev unhandled kind 0x%.4x", kinds[i]);
The only functions that know about the pointer and get called are those behind
the dev_to_host_cpy and host_to_dev_cpy - thus, they seemingly mess about with
the
unlocking?!?
* * *
Regarding your patch, I do not understand why you call twice unlock and
have trice TODO unlock; that does not seem to make any sense.
I think it is worthwhile to understand why plugin-nvptx.c unlocks the lock in
the non-error case - as you observe that it is not locked in the error case.
Additionally, it seems to make more sense to look into a revised patch of
Andrew's patch, your patch looks like a rather bad band aid.
Tobias
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