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Tweak to fix for thread concurency in looptri generation.

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Even if pointer assignment may be atomic, it does not prevent reordering
and other nifty compiler tricks, we need a memory barrier to ensure not
only that transferring pointer from wip array to final one is atomic,
but also that all previous writing to memory are “flushed” to
(visible by) all CPUs...

Thanks @sergey for finding the potential (though quite unlikely) issue.
This commit is contained in:
Bastien Montagne
2017-09-25 09:56:02 +02:00
parent cb6f07f59e
commit 01a3c6b204
3 changed files with 12 additions and 3 deletions
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5
source/blender/blenkernel/intern/cdderivedmesh.c
View File

@@ -34,6 +34,8 @@
* \ingroup bke
*/
#include "atomic_ops.h"
#include "BLI_math.h"
#include "BLI_edgehash.h"
#include "BLI_utildefines.h"
@@ -1928,7 +1930,8 @@ void CDDM_recalc_looptri(DerivedMesh *dm)
cddm->dm.looptris.array_wip);
BLI_assert(cddm->dm.looptris.array == NULL);
SWAP(MLoopTri *, cddm->dm.looptris.array, cddm->dm.looptris.array_wip);
atomic_cas_z((size_t *)&cddm->dm.looptris.array, *(size_t *)&cddm->dm.looptris.array, *(size_t *)&cddm->dm.looptris.array_wip);
cddm->dm.looptris.array_wip = NULL;
}
static void cdDM_free_internal(CDDerivedMesh *cddm)

5
source/blender/blenkernel/intern/editderivedmesh.c
View File

@@ -41,6 +41,8 @@
* is likely to be a little slow.
*/
#include "atomic_ops.h"
#include "BLI_math.h"
#include "BLI_jitter.h"
#include "BLI_bitmap.h"
@@ -662,7 +664,8 @@ static void emDM_recalcLoopTri(DerivedMesh *dm)
}
BLI_assert(dm->looptris.array == NULL);
SWAP(MLoopTri *, dm->looptris.array, dm->looptris.array_wip);
atomic_cas_z((size_t *)&dm->looptris.array, *(size_t *)&dm->looptris.array, *(size_t *)&dm->looptris.array_wip);
dm->looptris.array_wip = NULL;
}
static void emDM_foreachMappedVert(

5
source/blender/blenkernel/intern/subsurf_ccg.c
View File

@@ -42,6 +42,8 @@
#include <math.h>
#include <float.h>
#include "atomic_ops.h"
#include "MEM_guardedalloc.h"
#include "DNA_mesh_types.h"
@@ -4505,7 +4507,8 @@ static void ccgDM_recalcLoopTri(DerivedMesh *dm)
}
BLI_assert(dm->looptris.array == NULL);
SWAP(MLoopTri *, dm->looptris.array, dm->looptris.array_wip);
atomic_cas_z((size_t *)&dm->looptris.array, *(size_t *)&dm->looptris.array, *(size_t *)&dm->looptris.array_wip);
dm->looptris.array_wip = NULL;
}
static void ccgDM_calcNormals(DerivedMesh *dm)