This is a temporary fix for the deadlock problem over MX. The real

problem seems to come from the free list, but due to lack of time to
understand it completely, I provide this fix. Basically, there is no
waiting in the MX BTL anymore, if we cannot allocate a fragment we
rely on the PML to take the corrective actions.

This commit was SVN r20124.

ompi/mca/btl/mx/btl_mx_frag.h

@@ -63,26 +63,31 @@ OBJ_CLASS_DECLARATION(mca_btl_mx_frag_user_t);
  */
 
 #define MCA_BTL_MX_FRAG_ALLOC_EAGER(btl, frag, rc)                            \
-    {                                                                   \
+do {                                                                          \
     ompi_free_list_item_t *item;                                              \
-        OMPI_FREE_LIST_WAIT( &mca_btl_mx_component.mx_send_eager_frags, item, rc); \
+    OMPI_FREE_LIST_GET( &mca_btl_mx_component.mx_send_eager_frags, item, rc); \
+    if( OPAL_LIKELY(NULL != item) ) {                                         \
         frag = (mca_btl_mx_frag_t*) item;                                     \
         frag->mx_frag_list = &(mca_btl_mx_component.mx_send_eager_frags);     \
         frag->segment[0].seg_addr.pval = (void*)(frag+1);                     \
-    }
+    }                                                                         \
+} while(0)
 
 #define MCA_BTL_MX_FRAG_ALLOC_USER(btl, frag, rc)                            \
-    {                                                                   \
+do {                                                                         \
     ompi_free_list_item_t *item;                                             \
-        OMPI_FREE_LIST_WAIT( &mca_btl_mx_component.mx_send_user_frags, item, rc); \
+    OMPI_FREE_LIST_GET( &mca_btl_mx_component.mx_send_user_frags, item, rc); \
+    if( OPAL_LIKELY(NULL != item) ) {                                        \
         frag = (mca_btl_mx_frag_t*) item;                                    \
         frag->mx_frag_list = &(mca_btl_mx_component.mx_send_user_frags);     \
-    }
+    }                                                                        \
+} while(0)
 
 #define MCA_BTL_MX_FRAG_RETURN(btl, frag)                     \
-    {                                                                   \
-        OMPI_FREE_LIST_RETURN( frag->mx_frag_list, (ompi_free_list_item_t*)(frag)); \
-    }
+do {                                                          \
+    OMPI_FREE_LIST_RETURN( frag->mx_frag_list,                \
+                           (ompi_free_list_item_t*)(frag));   \
+} while(0)
 
 END_C_DECLS