I've corrected my patch accordingly to what you said. To diffirentiate
second case in destructor I've added pthread_setspecific
(gomp_tls_key, NULL) at the end of gomp_thread_start. So, destructor
can simply skip the case when pthread_getspecific (gomp_tls_key)
returns 0. I also think that it's better to set 0 in gomp_thread_start
explicitly as thread data is initialized by a local variable in this
function.
But, I see that pthread_getspecific always returns 0 in destrucor
because data pointer is implicitly set to 0 before destructor call in
glibc:
(pthread_create.c):
/* Always clear the data. */
level2[inner].data = NULL;
/* Make sure the data corresponds to a valid
key. This test fails if the key was
deallocated and also if it was
re-allocated. It is the user's
responsibility to free the memory in this
case. */
if (level2[inner].seq
== __pthread_keys[idx].seq
/* It is not necessary to register a destructor
function. */
&& __pthread_keys[idx].destr != NULL)
/* Call the user-provided destructor. */
__pthread_keys[idx].destr (data);
I suppose it's not necessary if everything is cleaned up in
gomp_thread_start and destructor. What do you think?
Changes are bootstrapped and regtested on x86_64-linux.
2014-09-19 Varvara Rainchik <varvara.rainc...@intel.com>
* libgomp.h (gomp_thread): For non TLS case create thread data.
* team.c (non_tls_thread_data_destructor,
create_non_tls_thread_data): New functions.
---
diff --git a/libgomp/libgomp.h b/libgomp/libgomp.h
index bcd5b34..2f33d99 100644
--- a/libgomp/libgomp.h
+++ b/libgomp/libgomp.h
@@ -467,9 +467,15 @@ static inline struct gomp_thread *gomp_thread (void)
}
#else
extern pthread_key_t gomp_tls_key;
-static inline struct gomp_thread *gomp_thread (void)
+extern struct gomp_thread *create_non_tls_thread_data (void);
+static struct gomp_thread *gomp_thread (void)
{
- return pthread_getspecific (gomp_tls_key);
+ struct gomp_thread *thr = pthread_getspecific (gomp_tls_key);
+ if (thr == NULL)
+ {
+ thr = create_non_tls_thread_data ();
+ }
+ return thr;
}
#endif
diff --git a/libgomp/team.c b/libgomp/team.c
index e6a6d8f..a692df8 100644
--- a/libgomp/team.c
+++ b/libgomp/team.c
@@ -41,6 +41,7 @@ pthread_key_t gomp_thread_destructor;
__thread struct gomp_thread gomp_tls_data;
#else
pthread_key_t gomp_tls_key;
+struct gomp_thread initial_thread_tls_data;
#endif
@@ -130,6 +131,7 @@ gomp_thread_start (void *xdata)
gomp_sem_destroy (&thr->release);
thr->thread_pool = NULL;
thr->task = NULL;
+ pthread_setspecific (gomp_tls_key, NULL);
return NULL;
}
@@ -222,8 +224,16 @@ gomp_free_pool_helper (void *thread_pool)
void
gomp_free_thread (void *arg __attribute__((unused)))
{
- struct gomp_thread *thr = gomp_thread ();
- struct gomp_thread_pool *pool = thr->thread_pool;
+ struct gomp_thread *thr;
+ struct gomp_thread_pool *pool;
+#ifdef HAVE_TLS
+ thr = gomp_thread ();
+#else
+ thr = pthread_getspecific (gomp_tls_key);
+ if (thr == NULL)
+ return;
+#endif
+ pool = thr->thread_pool;
if (pool)
{
if (pool->threads_used > 0)
@@ -910,6 +920,21 @@ gomp_team_end (void)
}
}
+/* Destructor for data created in create_non_tls_thread_data. */
+
+#ifndef HAVE_TLS
+void
+non_tls_thread_data_destructor (void *arg __attribute__((unused)))
+{
+ struct gomp_thread *thr = pthread_getspecific (gomp_tls_key);
+ if (thr != NULL && thr != &initial_thread_tls_data)
+ {
+ gomp_free_thread (arg);
+ free (thr);
+ pthread_setspecific (gomp_tls_key, NULL);
+ }
+}
+#endif
/* Constructors for this file. */
@@ -917,9 +942,7 @@ static void __attribute__((constructor))
initialize_team (void)
{
#ifndef HAVE_TLS
- static struct gomp_thread initial_thread_tls_data;
-
- pthread_key_create (&gomp_tls_key, NULL);
+ pthread_key_create (&gomp_tls_key, non_tls_thread_data_destructor);
pthread_setspecific (gomp_tls_key, &initial_thread_tls_data);
#endif
@@ -927,6 +950,19 @@ initialize_team (void)
gomp_fatal ("could not create thread pool destructor.");
}
+/* Create data for thread created by pthread_create. */
+
+#ifndef HAVE_TLS
+struct gomp_thread *create_non_tls_thread_data (void)
+{
+ struct gomp_thread *thr = gomp_malloc_cleared (sizeof (struct gomp_thread));
+ pthread_setspecific (gomp_tls_key, thr);
+ gomp_sem_init (&thr->release, 0);
+
+ return thr;
+}
+#endif
+
static void __attribute__((destructor))
team_destructor (void)
{
2014-09-02 14:36 GMT+04:00 Varvara Rainchik <varvara.s.rainc...@gmail.com>:
> May I use gomp_free_thread as a destructor for pthread_key_create?
> Then I'll make initial_thread_tls_data global for the first case, but
> how can I differentiate thread created by gomp_thread_start (second
> case)?
>
> 2014-09-01 14:51 GMT+04:00 Jakub Jelinek <ja...@redhat.com>:
>> On Fri, Aug 29, 2014 at 10:40:57AM -0700, Richard Henderson wrote:
>>> On 08/06/2014 03:05 AM, Varvara Rainchik wrote:
>>> > * libgomp.h (gomp_thread): For non TLS case create thread data.
>>> > * team.c (create_non_tls_thread_data): New function.
>>> >
>>> >
>>> > ---
>>> > diff --git a/libgomp/libgomp.h b/libgomp/libgomp.h
>>> > index a1482cc..cf3ec8f 100644
>>> > --- a/libgomp/libgomp.h
>>> > +++ b/libgomp/libgomp.h
>>> > @@ -479,9 +479,15 @@ static inline struct gomp_thread *gomp_thread (void)
>>> > }
>>> > #else
>>> > extern pthread_key_t gomp_tls_key;
>>> > +extern struct gomp_thread *create_non_tls_thread_data (void);
>>> > static inline struct gomp_thread *gomp_thread (void)
>>> > {
>>> > - return pthread_getspecific (gomp_tls_key);
>>> > + struct gomp_thread *thr = pthread_getspecific (gomp_tls_key);
>>> > + if (thr == NULL)
>>> > + {
>>> > + thr = create_non_tls_thread_data ();
>>> > + }
>>> > + return thr;
>>> > }
>>>
>>> This should never happen.
>>
>> I guess it can happen if you mix up explicit pthread_create and libgomp APIs.
>> initialize_team will only initialize it in the initial thread, while if you
>> use #pragma omp ... or omp_* calls from a thread created with
>> pthread_create, in the !HAVE_TLS case pthread_getspecific will return NULL.
>>
>> Now, the patch doesn't handle that case completely though (and is badly
>> formatted), the problem is that if we allocate in the !HAVE_TLS case
>> in non-initial thread the TLS data, we want to free them again, so that
>> would mean pthread_key_create with non-NULL destructor, and then we need to
>> differentiate in between the 3 cases - key equal to &initial_thread_tls_data
>> (would need to move out of the block context), no freeing needed, thread
>> created by gomp_thread_start, no freeing needed, otherwise free.
>>
>>> The thread-specific data is set in gomp_thread_start and initialize_team.
>>>
>>> Where are you getting a call to gomp_thread that hasn't been through one of
>>> those functions?
>>
>> Jakub
