2 files changed, 20 insertions, 3 deletions

diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index f1345828c7c5..8670f1575fe1 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -105,7 +105,19 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer,
  * size is in bytes for each per CPU buffer.
  */
 struct ring_buffer *
-ring_buffer_alloc(unsigned long size, unsigned flags);
+__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
+
+/*
+ * Because the ring buffer is generic, if other users of the ring buffer get
+ * traced by ftrace, it can produce lockdep warnings. We need to keep each
+ * ring buffer's lock class separate.
+ */
+#define ring_buffer_alloc(size, flags)                  \
+({                                                      \
+        static struct lock_class_key __key;             \
+        __ring_buffer_alloc((size), (flags), &__key);   \
+})
+
 void ring_buffer_free(struct ring_buffer *buffer);
 
 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size);
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 7102d7a2fadb..22878b0d370c 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -426,6 +426,8 @@ struct ring_buffer {
         atomic_t                        record_disabled;
         cpumask_var_t                   cpumask;
 
+        struct lock_class_key           *reader_lock_key;
+
         struct mutex                    mutex;
 
         struct ring_buffer_per_cpu      **buffers;
@@ -565,6 +567,7 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
         cpu_buffer->cpu = cpu;
         cpu_buffer->buffer = buffer;
         spin_lock_init(&cpu_buffer->reader_lock);
+        lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key);
         cpu_buffer->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
         INIT_LIST_HEAD(&cpu_buffer->pages);
 
@@ -635,7 +638,8 @@ static int rb_cpu_notify(struct notifier_block *self,
  * when the buffer wraps. If this flag is not set, the buffer will
  * drop data when the tail hits the head.
  */
-struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags)
+struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
+                                        struct lock_class_key *key)
 {
         struct ring_buffer *buffer;
         int bsize;
@@ -658,6 +662,7 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags)
         buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
         buffer->flags = flags;
         buffer->clock = trace_clock_local;
+        buffer->reader_lock_key = key;
 
         /* need at least two pages */
         if (buffer->pages == 1)
@@ -715,7 +720,7 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags)
         kfree(buffer);
         return NULL;
 }
-EXPORT_SYMBOL_GPL(ring_buffer_alloc);
+EXPORT_SYMBOL_GPL(__ring_buffer_alloc);
 
 /**
  * ring_buffer_free - free a ring buffer.