fix bug #406: Using OpenMP and Eigen causes infinite loop/deadlock

(transplanted from fd52daae87b7b1cc2618b12b4579a0eab5194d48
)

1 files changed, 7 insertions, 10 deletions

diff --git a/Eigen/src/Core/products/GeneralBlockPanelKernel.h b/Eigen/src/Core/products/GeneralBlockPanelKernel.h
index e8a0fbbde..8ace428ab 100644
--- a/Eigen/src/Core/products/GeneralBlockPanelKernel.h
+++ b/Eigen/src/Core/products/GeneralBlockPanelKernel.h
@@ -30,19 +30,16 @@ namespace internal {
 template<typename _LhsScalar, typename _RhsScalar, bool _ConjLhs=false, bool _ConjRhs=false>
 class gebp_traits;
 
+std::ptrdiff_t manage_caching_sizes_second_if_negative(std::ptrdiff_t a, std::ptrdiff_t b)
+{
+  return a<=0 ? b : a;
+}
+
 /** \internal */
 inline void manage_caching_sizes(Action action, std::ptrdiff_t* l1=0, std::ptrdiff_t* l2=0)
 {
-  static std::ptrdiff_t m_l1CacheSize = 0;
-  static std::ptrdiff_t m_l2CacheSize = 0;
-  if(m_l1CacheSize==0)
-  {
-    m_l1CacheSize = queryL1CacheSize();
-    m_l2CacheSize = queryTopLevelCacheSize();
-
-    if(m_l1CacheSize<=0) m_l1CacheSize = 8 * 1024;
-    if(m_l2CacheSize<=0) m_l2CacheSize = 1 * 1024 * 1024;
-  }
+  static std::ptrdiff_t m_l1CacheSize = manage_caching_sizes_second_if_negative(queryL1CacheSize(),8 * 1024);
+  static std::ptrdiff_t m_l2CacheSize = manage_caching_sizes_second_if_negative(queryTopLevelCacheSize(),1*1024*1024);
 
   if(action==SetAction)
   {