llist: Make some llist functions inline

Because llist code will be used in performance critical scheduler
code path, make llist_add() and llist_del_all() inline to avoid
function calling overhead and related 'glue' overhead.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1315461646-1379-2-git-send-email-ying.huang@intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 58 insertions, 6 deletions

diff --git a/include/linux/llist.h b/include/linux/llist.h
index aa0c8b5b3cd0..3eccdfd66096 100644
--- a/include/linux/llist.h
+++ b/include/linux/llist.h
@@ -37,8 +37,28 @@
  * architectures that don't have NMI-safe cmpxchg implementation, the
  * list can NOT be used in NMI handler.  So code uses the list in NMI
  * handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
+ *
+ * Copyright 2010,2011 Intel Corp.
+ *   Author: Huang Ying <ying.huang@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include <linux/kernel.h>
+#include <asm/system.h>
+#include <asm/processor.h>
+
 struct llist_head {
         struct llist_node *first;
 };
@@ -113,14 +133,46 @@ static inline void init_llist_head(struct llist_head *list)
  * test whether the list is empty without deleting something from the
  * list.
  */
-static inline int llist_empty(const struct llist_head *head)
+static inline bool llist_empty(const struct llist_head *head)
 {
         return ACCESS_ONCE(head->first) == NULL;
 }
 
-void llist_add(struct llist_node *new, struct llist_head *head);
-void llist_add_batch(struct llist_node *new_first, struct llist_node *new_last,
-                     struct llist_head *head);
-struct llist_node *llist_del_first(struct llist_head *head);
-struct llist_node *llist_del_all(struct llist_head *head);
+/**
+ * llist_add - add a new entry
+ * @new:        new entry to be added
+ * @head:       the head for your lock-less list
+ */
+static inline void llist_add(struct llist_node *new, struct llist_head *head)
+{
+        struct llist_node *entry, *old_entry;
+
+#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+        BUG_ON(in_nmi());
+#endif
+
+        entry = head->first;
+        do {
+                old_entry = entry;
+                new->next = entry;
+                cpu_relax();
+        } while ((entry = cmpxchg(&head->first, old_entry, new)) != old_entry);
+}
+
+/**
+ * llist_del_all - delete all entries from lock-less list
+ * @head:       the head of lock-less list to delete all entries
+ *
+ * If list is empty, return NULL, otherwise, delete all entries and
+ * return the pointer to the first entry.  The order of entries
+ * deleted is from the newest to the oldest added one.
+ */
+static inline struct llist_node *llist_del_all(struct llist_head *head)
+{
+#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+        BUG_ON(in_nmi());
+#endif
+
+        return xchg(&head->first, NULL);
+}
 #endif /* LLIST_H */