[PATCH -next v2] mm/mmap_lock: fix warning when CONFIG_TRACING is not defined

[Bixuan Cui <cuibixuan@huawei.com>]

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Fix the warning: [-Wunused-function]
mm/mmap_lock.c:157:20: warning: ‘get_mm_memcg_path’ defined but not used
 static const char *get_mm_memcg_path(struct mm_struct *mm)
                    ^~~~~~~~~~~~~~~~~

Move get_mm_memcg_path() into #ifdef CONFIG_TRACING.

Signed-off-by: Bixuan Cui <cuibixuan@huawei.com>
Acked-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
Changes in v2:
Move get_mm_memcg_path() into #ifdef CONFIG_TRACING to fix the warning.

 mm/mmap_lock.c | 60 ++++++++++++++++++++++++++------------------------
 1 file changed, 31 insertions(+), 29 deletions(-)

diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c
index 03ee85c696ef..29e99af73144 100644
--- a/mm/mmap_lock.c
+++ b/mm/mmap_lock.c
@@ -142,6 +142,37 @@ static inline void put_memcg_path_buf(void)
 	rcu_read_unlock();
 }
 
+#define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
+	do {                                                                   \
+		const char *memcg_path;                                        \
+		preempt_disable();                                             \
+		memcg_path = get_mm_memcg_path(mm);                            \
+		trace_mmap_lock_##type(mm,                                     \
+				       memcg_path != NULL ? memcg_path : "",   \
+				       ##__VA_ARGS__);                         \
+		if (likely(memcg_path != NULL))                                \
+			put_memcg_path_buf();                                  \
+		preempt_enable();                                              \
+	} while (0)
+
+#else /* !CONFIG_MEMCG */
+
+int trace_mmap_lock_reg(void)
+{
+	return 0;
+}
+
+void trace_mmap_lock_unreg(void)
+{
+}
+
+#define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
+	trace_mmap_lock_##type(mm, "", ##__VA_ARGS__)
+
+#endif /* CONFIG_MEMCG */
+
+#ifdef CONFIG_TRACING
+#ifdef CONFIG_MEMCG
 /*
  * Write the given mm_struct's memcg path to a percpu buffer, and return a
  * pointer to it. If the path cannot be determined, or no buffer was available
@@ -175,37 +206,8 @@ static const char *get_mm_memcg_path(struct mm_struct *mm)
 out:
 	return buf;
 }
-
-#define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
-	do {                                                                   \
-		const char *memcg_path;                                        \
-		preempt_disable();                                             \
-		memcg_path = get_mm_memcg_path(mm);                            \
-		trace_mmap_lock_##type(mm,                                     \
-				       memcg_path != NULL ? memcg_path : "",   \
-				       ##__VA_ARGS__);                         \
-		if (likely(memcg_path != NULL))                                \
-			put_memcg_path_buf();                                  \
-		preempt_enable();                                              \
-	} while (0)
-
-#else /* !CONFIG_MEMCG */
-
-int trace_mmap_lock_reg(void)
-{
-	return 0;
-}
-
-void trace_mmap_lock_unreg(void)
-{
-}
-
-#define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
-	trace_mmap_lock_##type(mm, "", ##__VA_ARGS__)
-
 #endif /* CONFIG_MEMCG */
 
-#ifdef CONFIG_TRACING
 /*
  * Trace calls must be in a separate file, as otherwise there's a circular
  * dependency between linux/mmap_lock.h and trace/events/mmap_lock.h.
-- 
2.17.1