[PATCH v1] ring-buffer: Rename ring_buffer_size() to ring_buffer_capacity()

[Vincent Donnefort <vdonnefort@google.com>]

Since commit 8a5f63637890 ("ring-buffer: Fix subbuf resize race with ring
buffer readers"), "capacity" refers to the memory available for events
(excluding subbuffer headers) while "size" refers to the raw allocation.
ring_buffer_size() actually calculates this event capacity. Rename it to
ring_buffer_capacity() to align with this convention.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index afc7daa6ee7d..9e23ab66176b 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -165,7 +165,7 @@ void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
 
-unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
+unsigned long ring_buffer_capacity(struct trace_buffer *buffer, int cpu);
 unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer);
 
 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 9c03a555a6ba..2940ff763354 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -6547,18 +6547,23 @@ void ring_buffer_iter_advance(struct ring_buffer_iter *iter)
 EXPORT_SYMBOL_GPL(ring_buffer_iter_advance);
 
 /**
- * ring_buffer_size - return the size of the ring buffer (in bytes)
+ * ring_buffer_capacity - return the capacity of the ring buffer (in bytes)
  * @buffer: The ring buffer.
- * @cpu: The CPU to get ring buffer size from.
+ * @cpu: The CPU to get ring buffer capacity from.
+ *
+ * Capacity is the total memory available for recording event data in the
+ * ring buffer. It excludes subbufer headers.
+ *
+ * Returns the capacity in bytes, or 0 if the CPU is not set in the buffer mask.
  */
-unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu)
+unsigned long ring_buffer_capacity(struct trace_buffer *buffer, int cpu)
 {
 	if (!cpumask_test_cpu(cpu, buffer->cpumask))
 		return 0;
 
 	return rb_subbuf_capacity(buffer) * buffer->buffers[cpu]->nr_pages;
 }
-EXPORT_SYMBOL_GPL(ring_buffer_size);
+EXPORT_SYMBOL_GPL(ring_buffer_capacity);
 
 /**
  * ring_buffer_max_event_size - return the max data size of an event
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8658cad53cb5..f0251788ec75 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4712,9 +4712,9 @@ void trace_set_buffer_entries(struct array_buffer *buf, unsigned long val)
 static void update_buffer_entries(struct array_buffer *buf, int cpu)
 {
 	if (cpu == RING_BUFFER_ALL_CPUS) {
-		trace_set_buffer_entries(buf, ring_buffer_size(buf->buffer, 0));
+		trace_set_buffer_entries(buf, ring_buffer_capacity(buf->buffer, 0));
 	} else {
-		per_cpu_ptr(buf->data, cpu)->entries = ring_buffer_size(buf->buffer, cpu);
+		per_cpu_ptr(buf->data, cpu)->entries = ring_buffer_capacity(buf->buffer, cpu);
 	}
 }
 
@@ -8476,7 +8476,7 @@ int allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int
 
 	/* Allocate the first page for all buffers */
 	trace_set_buffer_entries(&tr->array_buffer,
-				 ring_buffer_size(tr->array_buffer.buffer, 0));
+				 ring_buffer_capacity(tr->array_buffer.buffer, 0));
 
 	return 0;
 }

base-commit: df2908090cda368b01ff43709f51890076c56157
-- 
2.55.0.979.g7e5102b832-goog