6138 don't abuse atomic_cas_*

*** 69,79 ****
  
  void
  mem_node_add_slice(pfn_t start, pfn_t end)
  {
          int mnode;
-         mnodeset_t newmask, oldmask;
  
          /*
           * DR will pass us the first pfn that is allocatable.
           * We need to round down to get the real start of
           * the slice.
--- 69,78 ----
*** 96,110 ****
                          mem_node_config[mnode].physmax = end;
          } else {
                  mem_node_config[mnode].physbase = start;
                  mem_node_config[mnode].physmax = end;
                  atomic_inc_16(&num_memnodes);
!                 do {
!                         oldmask = memnodes_mask;
!                         newmask = memnodes_mask | (1ull << mnode);
!                 } while (atomic_cas_64(&memnodes_mask, oldmask, newmask) !=
!                     oldmask);
          }
  
          /*
           * Inform the common lgrp framework about the new memory
           */
--- 95,105 ----
                          mem_node_config[mnode].physmax = end;
          } else {
                  mem_node_config[mnode].physbase = start;
                  mem_node_config[mnode].physmax = end;
                  atomic_inc_16(&num_memnodes);
!                 atomic_or_64(&memnodes_mask, 1ull << mnode);
          }
  
          /*
           * Inform the common lgrp framework about the new memory
           */
*** 121,131 ****
  void
  mem_node_del_slice(pfn_t start, pfn_t end)
  {
          int mnode;
          pgcnt_t delta_pgcnt, node_size;
-         mnodeset_t omask, nmask;
  
          if (mem_node_physalign) {
                  start &= ~(btop(mem_node_physalign) - 1);
                  end = roundup(end, btop(mem_node_physalign)) - 1;
          }
--- 116,125 ----
*** 157,170 ****
  
                  /*
                   * Delete the whole node.
                   */
                  ASSERT(MNODE_PGCNT(mnode) == 0);
!                 do {
!                         omask = memnodes_mask;
!                         nmask = omask & ~(1ull << mnode);
!                 } while (atomic_cas_64(&memnodes_mask, omask, nmask) != omask);
                  atomic_dec_16(&num_memnodes);
                  mem_node_config[mnode].exists = 0;
          }
  }
  
--- 151,161 ----
  
                  /*
                   * Delete the whole node.
                   */
                  ASSERT(MNODE_PGCNT(mnode) == 0);
!                 atomic_and_64(&memnodes_mask, ~(1ull << mnode));
                  atomic_dec_16(&num_memnodes);
                  mem_node_config[mnode].exists = 0;
          }
  }
  
*** 221,231 ****
   */
  int
  mem_node_alloc()
  {
          int mnode;
-         mnodeset_t newmask, oldmask;
  
          /*
           * Find an unused memnode.  Update it atomically to prevent
           * a first time memnode creation race.
           */
--- 212,221 ----
*** 238,251 ****
                  panic("Out of free memnodes\n");
  
          mem_node_config[mnode].physbase = (pfn_t)-1l;
          mem_node_config[mnode].physmax = 0;
          atomic_inc_16(&num_memnodes);
!         do {
!                 oldmask = memnodes_mask;
!                 newmask = memnodes_mask | (1ull << mnode);
!         } while (atomic_cas_64(&memnodes_mask, oldmask, newmask) != oldmask);
  
          return (mnode);
  }
  
  /*
--- 228,238 ----
                  panic("Out of free memnodes\n");
  
          mem_node_config[mnode].physbase = (pfn_t)-1l;
          mem_node_config[mnode].physmax = 0;
          atomic_inc_16(&num_memnodes);
!         atomic_or_64(&memnodes_mask, 1ull << mnode);
  
          return (mnode);
  }
  
  /*