Mesa (master): swrast: fix delayed texel buffer allocation regression for OpenMP
Brian Paul
brianp at kemper.freedesktop.org
Tue Jan 7 15:12:04 UTC 2014
Module: Mesa
Branch: master
Commit: 2a0fb946e147f5482c93702fbf46ffdf5208f57c
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=2a0fb946e147f5482c93702fbf46ffdf5208f57c
Author: Andreas Fänger <a.faenger at e-sign.com>
Date: Tue Jan 7 03:10:00 2014 -0700
swrast: fix delayed texel buffer allocation regression for OpenMP
Commit 9119269ca14ed42b51c7d8e2e662500311b29fa3 moved the texel
buffer allocation to _swrast_texture_span(), however, when compiled
with OpenMP support this code already runs multi-threaded so a
critical section is required to prevent multiple allocations and
rendering errors.
Cc: "10.0" <mesa-stable at lists.freedesktop.org>
Reviewed-by: Brian Paul <brianp at vmware.com>
---
src/mesa/swrast/s_texcombine.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/src/mesa/swrast/s_texcombine.c b/src/mesa/swrast/s_texcombine.c
index 7e07f4f..297491e 100644
--- a/src/mesa/swrast/s_texcombine.c
+++ b/src/mesa/swrast/s_texcombine.c
@@ -602,6 +602,14 @@ _swrast_texture_span( struct gl_context *ctx, SWspan *span )
if (!swrast->TexelBuffer) {
#ifdef _OPENMP
const GLint maxThreads = omp_get_max_threads();
+
+ /* TexelBuffer memory allocation needs to be done in a critical section
+ * as this code runs in a parallel loop.
+ * When entering the section, first check if TexelBuffer has been
+ * initialized already by another thread while this thread was waiting.
+ */
+ #pragma omp critical
+ if (!swrast->TexelBuffer) {
#else
const GLint maxThreads = 1;
#endif
@@ -613,6 +621,10 @@ _swrast_texture_span( struct gl_context *ctx, SWspan *span )
swrast->TexelBuffer =
malloc(ctx->Const.FragmentProgram.MaxTextureImageUnits * maxThreads *
SWRAST_MAX_WIDTH * 4 * sizeof(GLfloat));
+#ifdef _OPENMP
+ } /* critical section */
+#endif
+
if (!swrast->TexelBuffer) {
_mesa_error(ctx, GL_OUT_OF_MEMORY, "texture_combine");
return;
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