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v2.x: coll/libnbc: fix race condition with multi threaded apps #2441

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Dec 5, 2016
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v2.x: coll/libnbc: fix race condition with multi threaded apps #2441

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6155b71
coll/libnbc: fix race condition with multi threaded apps
ggouaillardet Nov 21, 2016
ad8c128
coll/libnbc: add some comments on how locks are used
ggouaillardet Nov 30, 2016
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5 changes: 3 additions & 2 deletions ompi/mca/coll/libnbc/coll_libnbc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@
* Copyright (c) 2008 Cisco Systems, Inc. All rights reserved.
* Copyright (c) 2013-2015 Los Alamos National Security, LLC. All rights
* reserved.
* Copyright (c) 2014-2015 Research Organization for Information Science
* Copyright (c) 2014-2016 Research Organization for Information Science
* and Technology (RIST). All rights reserved.
* Copyright (c) 2016 IBM Corporation. All rights reserved.
* $COPYRIGHT$
Expand Down Expand Up @@ -75,7 +75,8 @@ struct ompi_coll_libnbc_component_t {
opal_free_list_t requests;
opal_list_t active_requests;
int32_t active_comms;
opal_atomic_lock_t progress_lock;
opal_atomic_lock_t progress_lock; /* protect from recursive calls */
opal_mutex_t lock; /* protect access to the active_requests list */
};
typedef struct ompi_coll_libnbc_component_t ompi_coll_libnbc_component_t;

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11 changes: 11 additions & 0 deletions ompi/mca/coll/libnbc/coll_libnbc_component.c
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Original file line number Diff line number Diff line change
Expand Up @@ -91,6 +91,7 @@ libnbc_open(void)

OBJ_CONSTRUCT(&mca_coll_libnbc_component.requests, opal_free_list_t);
OBJ_CONSTRUCT(&mca_coll_libnbc_component.active_requests, opal_list_t);
OBJ_CONSTRUCT(&mca_coll_libnbc_component.lock, opal_mutex_t);
ret = opal_free_list_init (&mca_coll_libnbc_component.requests,
sizeof(ompi_coll_libnbc_request_t), 8,
OBJ_CLASS(ompi_coll_libnbc_request_t),
Expand All @@ -115,6 +116,7 @@ libnbc_close(void)

OBJ_DESTRUCT(&mca_coll_libnbc_component.requests);
OBJ_DESTRUCT(&mca_coll_libnbc_component.active_requests);
OBJ_DESTRUCT(&mca_coll_libnbc_component.lock);

return OMPI_SUCCESS;
}
Expand Down Expand Up @@ -261,15 +263,22 @@ ompi_coll_libnbc_progress(void)
ompi_coll_libnbc_request_t* request, *next;
int res;

/* return if invoked recursively */
if (opal_atomic_trylock(&mca_coll_libnbc_component.progress_lock)) return 0;

/* process active requests, and use mca_coll_libnbc_component.lock to access the
* mca_coll_libnbc_component.active_requests list */
OPAL_THREAD_LOCK(&mca_coll_libnbc_component.lock);
OPAL_LIST_FOREACH_SAFE(request, next, &mca_coll_libnbc_component.active_requests,
ompi_coll_libnbc_request_t) {
OPAL_THREAD_UNLOCK(&mca_coll_libnbc_component.lock);
res = NBC_Progress(request);
if( NBC_CONTINUE != res ) {
/* done, remove and complete */
OPAL_THREAD_LOCK(&mca_coll_libnbc_component.lock);
opal_list_remove_item(&mca_coll_libnbc_component.active_requests,
&request->super.super.super);
OPAL_THREAD_UNLOCK(&mca_coll_libnbc_component.lock);

if( OMPI_SUCCESS == res || NBC_OK == res || NBC_SUCCESS == res ) {
request->super.req_status.MPI_ERROR = OMPI_SUCCESS;
Expand All @@ -281,7 +290,9 @@ ompi_coll_libnbc_progress(void)
ompi_request_complete(&request->super, true);
OPAL_THREAD_UNLOCK(&ompi_request_lock);
}
OPAL_THREAD_LOCK(&mca_coll_libnbc_component.lock);
}
OPAL_THREAD_UNLOCK(&mca_coll_libnbc_component.lock);

opal_atomic_unlock(&mca_coll_libnbc_component.progress_lock);

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2 changes: 2 additions & 0 deletions ompi/mca/coll/libnbc/nbc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -702,7 +702,9 @@ int NBC_Start(NBC_Handle *handle, NBC_Schedule *schedule) {
if (OPAL_UNLIKELY(OMPI_SUCCESS != res)) {
return res;
}
OPAL_THREAD_LOCK(&mca_coll_libnbc_component.lock);
opal_list_append(&mca_coll_libnbc_component.active_requests, &(handle->super.super.super));
OPAL_THREAD_UNLOCK(&mca_coll_libnbc_component.lock);

return OMPI_SUCCESS;
}
Expand Down