llist: define macro to check NMI safe cmpxchg

To make code cleaner and reduce code duplication.  Thanks Peter
Zijlstra for reminding.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <>

diff --git a/include/linux/llist.h b/include/linux/llist.h
index 9be482e024ded117854b295cb2be530c626cf947..4fd3081dd68ff012f4f4192a1c97315008da86dc 100644 (file)
--- a/include/linux/llist.h
+++ b/include/linux/llist.h
@@ -70,6 +70,12 @@ struct llist_node {
 #define LLIST_HEAD_INIT(name)  { NULL }
 #define LLIST_HEAD(name)       struct llist_head name = LLIST_HEAD_INIT(name)
 
+#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+#define CHECK_NMI_SAFE_CMPXCHG()
+#else
+#define CHECK_NMI_SAFE_CMPXCHG()       BUG_ON(in_nmi())
+#endif
+
 /**
  * init_llist_head - initialize lock-less list head
  * @head:      the head for your lock-less list
@@ -147,9 +153,7 @@ 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
+       CHECK_NMI_SAFE_CMPXCHG();
 
        entry = head->first;
        do {
@@ -171,9 +175,7 @@ static inline void llist_add_batch(struct llist_node *new_first,
 {
        struct llist_node *entry, *old_entry;
 
-#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
-       BUG_ON(in_nmi());
-#endif
+       CHECK_NMI_SAFE_CMPXCHG();
 
        entry = head->first;
        do {
@@ -201,9 +203,7 @@ static inline struct llist_node *llist_del_first(struct llist_head *head)
 {
        struct llist_node *entry, *old_entry, *next;
 
-#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
-       BUG_ON(in_nmi());
-#endif
+       CHECK_NMI_SAFE_CMPXCHG();
 
        entry = head->first;
        do {
@@ -227,9 +227,7 @@ static inline struct llist_node *llist_del_first(struct llist_head *head)
  */
 static inline struct llist_node *llist_del_all(struct llist_head *head)
 {
-#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
-       BUG_ON(in_nmi());
-#endif
+       CHECK_NMI_SAFE_CMPXCHG();
 
        return xchg(&head->first, NULL);
 }