ring-buffer: add api to allow a tracer to change clock source
This patch adds a new function called ring_buffer_set_clock that
allows a tracer to assign its own clock source to the buffer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 58128ad..bbf5192 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -180,29 +180,6 @@
#include "trace.h"
-/* Up this if you want to test the TIME_EXTENTS and normalization */
-#define DEBUG_SHIFT 0
-
-u64 ring_buffer_time_stamp(int cpu)
-{
- u64 time;
-
- preempt_disable_notrace();
- /* shift to debug/test normalization and TIME_EXTENTS */
- time = trace_clock_local() << DEBUG_SHIFT;
- preempt_enable_no_resched_notrace();
-
- return time;
-}
-EXPORT_SYMBOL_GPL(ring_buffer_time_stamp);
-
-void ring_buffer_normalize_time_stamp(int cpu, u64 *ts)
-{
- /* Just stupid testing the normalize function and deltas */
- *ts >>= DEBUG_SHIFT;
-}
-EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp);
-
#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array))
#define RB_ALIGNMENT 4U
#define RB_MAX_SMALL_DATA 28
@@ -374,6 +351,7 @@
#ifdef CONFIG_HOTPLUG_CPU
struct notifier_block cpu_notify;
#endif
+ u64 (*clock)(void);
};
struct ring_buffer_iter {
@@ -394,6 +372,30 @@
_____ret; \
})
+/* Up this if you want to test the TIME_EXTENTS and normalization */
+#define DEBUG_SHIFT 0
+
+u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu)
+{
+ u64 time;
+
+ preempt_disable_notrace();
+ /* shift to debug/test normalization and TIME_EXTENTS */
+ time = buffer->clock() << DEBUG_SHIFT;
+ preempt_enable_no_resched_notrace();
+
+ return time;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_time_stamp);
+
+void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
+ int cpu, u64 *ts)
+{
+ /* Just stupid testing the normalize function and deltas */
+ *ts >>= DEBUG_SHIFT;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp);
+
/**
* check_pages - integrity check of buffer pages
* @cpu_buffer: CPU buffer with pages to test
@@ -569,6 +571,7 @@
buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
buffer->flags = flags;
+ buffer->clock = trace_clock_local;
/* need at least two pages */
if (buffer->pages == 1)
@@ -645,6 +648,12 @@
}
EXPORT_SYMBOL_GPL(ring_buffer_free);
+void ring_buffer_set_clock(struct ring_buffer *buffer,
+ u64 (*clock)(void))
+{
+ buffer->clock = clock;
+}
+
static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer);
static void
@@ -1191,7 +1200,7 @@
cpu_buffer->tail_page = next_page;
/* reread the time stamp */
- *ts = ring_buffer_time_stamp(cpu_buffer->cpu);
+ *ts = ring_buffer_time_stamp(buffer, cpu_buffer->cpu);
cpu_buffer->tail_page->page->time_stamp = *ts;
}
@@ -1334,7 +1343,7 @@
if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000))
return NULL;
- ts = ring_buffer_time_stamp(cpu_buffer->cpu);
+ ts = ring_buffer_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu);
/*
* Only the first commit can update the timestamp.
@@ -2051,7 +2060,8 @@
case RINGBUF_TYPE_DATA:
if (ts) {
*ts = cpu_buffer->read_stamp + event->time_delta;
- ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts);
+ ring_buffer_normalize_time_stamp(buffer,
+ cpu_buffer->cpu, ts);
}
return event;
@@ -2112,7 +2122,8 @@
case RINGBUF_TYPE_DATA:
if (ts) {
*ts = iter->read_stamp + event->time_delta;
- ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts);
+ ring_buffer_normalize_time_stamp(buffer,
+ cpu_buffer->cpu, ts);
}
return event;