ring-buffer: Place duplicate expression into a single function

While discussing the strictness of the 80 character limit on the
Kernel Summit Discussion mailing list, I showed examples that I
broke that limit slightly with some algorithms. In discussing with
John Linville, what looked better, I realized that two of the
80 char breaking culprits were an identical expression.

As a clean up, this patch moves the identical expression into its
own helper function and that is used instead. As a side effect,
the offending code is now under the 80 character limit. :-)

This clean up code also changes the expression from

	(A - B) - C  to  A - (B + C)

This makes the code look a little nicer too.

Cc: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 19cccc3c302871beae5fd39ad937b0791a2e785d..ef27017caa56dc7fa9b08f38549354376927b417 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2606,6 +2606,19 @@ void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu)
 }
 EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu);
 
+/*
+ * The total entries in the ring buffer is the running counter
+ * of entries entered into the ring buffer, minus the sum of
+ * the entries read from the ring buffer and the number of
+ * entries that were overwritten.
+ */
+static inline unsigned long
+rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer)
+{
+       return local_read(&cpu_buffer->entries) -
+               (local_read(&cpu_buffer->overrun) + cpu_buffer->read);
+}
+
 /**
  * ring_buffer_entries_cpu - get the number of entries in a cpu buffer
  * @buffer: The ring buffer
@@ -2614,16 +2627,13 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu);
 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu)
 {
        struct ring_buffer_per_cpu *cpu_buffer;
-       unsigned long ret;
 
        if (!cpumask_test_cpu(cpu, buffer->cpumask))
                return 0;
 
        cpu_buffer = buffer->buffers[cpu];
-       ret = (local_read(&cpu_buffer->entries) - local_read(&cpu_buffer->overrun))
-               - cpu_buffer->read;
 
-       return ret;
+       return rb_num_of_entries(cpu_buffer);
 }
 EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu);
 
@@ -2684,8 +2694,7 @@ unsigned long ring_buffer_entries(struct ring_buffer *buffer)
        /* if you care about this being correct, lock the buffer */
        for_each_buffer_cpu(buffer, cpu) {
                cpu_buffer = buffer->buffers[cpu];
-               entries += (local_read(&cpu_buffer->entries) -
-                           local_read(&cpu_buffer->overrun)) - cpu_buffer->read;
+               entries += rb_num_of_entries(cpu_buffer);
        }
 
        return entries;