ring-buffer: move calculation of event length
The event length is calculated and passed in to rb_reserve_next_event
in two different locations. Having rb_reserve_next_event do the
calculations directly makes only one location to do the change and
causes the calculation to be inlined by gcc.
Before:
text data bss dec hex filename
16538 24 12 16574 40be kernel/trace/ring_buffer.o
After:
text data bss dec hex filename
16490 24 12 16526 408e kernel/trace/ring_buffer.o
[ Impact: smaller more efficient code ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index fe40f6c..493cba4 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -367,6 +367,9 @@
#define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE)
+/* Max payload is BUF_PAGE_SIZE - header (8bytes) */
+#define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2))
+
int ring_buffer_print_page_header(struct trace_seq *s)
{
struct buffer_data_page field;
@@ -1396,6 +1399,7 @@
int commit = 0;
int nr_loops = 0;
+ length = rb_calculate_event_length(length);
again:
/*
* We allow for interrupts to reenter here and do a trace.
@@ -1552,8 +1556,7 @@
if (atomic_read(&cpu_buffer->record_disabled))
goto out;
- length = rb_calculate_event_length(length);
- if (length > BUF_PAGE_SIZE)
+ if (length > BUF_MAX_DATA_SIZE)
goto out;
event = rb_reserve_next_event(cpu_buffer, length);
@@ -1758,7 +1761,6 @@
{
struct ring_buffer_per_cpu *cpu_buffer;
struct ring_buffer_event *event;
- unsigned long event_length;
void *body;
int ret = -EBUSY;
int cpu, resched;
@@ -1781,8 +1783,10 @@
if (atomic_read(&cpu_buffer->record_disabled))
goto out;
- event_length = rb_calculate_event_length(length);
- event = rb_reserve_next_event(cpu_buffer, event_length);
+ if (length > BUF_MAX_DATA_SIZE)
+ goto out;
+
+ event = rb_reserve_next_event(cpu_buffer, length);
if (!event)
goto out;
