ring-buffer: Add event descriptor to simplify passing data
Add rb_event_info descriptor to pass event info to functions a bit
easier than using a bunch of parameters. This will also allow for
changing the code around a bit to find better fast paths.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 6260717c1..ba8f25f 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -400,6 +400,17 @@
};
/*
+ * Structure to hold event state and handle nested events.
+ */
+struct rb_event_info {
+ u64 ts;
+ u64 delta;
+ unsigned long length;
+ struct buffer_page *tail_page;
+ int add_timestamp;
+};
+
+/*
* Used for which event context the event is in.
* NMI = 0
* IRQ = 1
@@ -2000,9 +2011,12 @@
*/
static void
rb_update_event(struct ring_buffer_per_cpu *cpu_buffer,
- struct ring_buffer_event *event, unsigned length,
- int add_timestamp, u64 delta)
+ struct ring_buffer_event *event,
+ struct rb_event_info *info)
{
+ unsigned length = info->length;
+ u64 delta = info->delta;
+
/* Only a commit updates the timestamp */
if (unlikely(!rb_event_is_commit(cpu_buffer, event)))
delta = 0;
@@ -2011,7 +2025,7 @@
* If we need to add a timestamp, then we
* add it to the start of the resevered space.
*/
- if (unlikely(add_timestamp)) {
+ if (unlikely(info->add_timestamp)) {
event = rb_add_time_stamp(event, delta);
length -= RB_LEN_TIME_EXTEND;
delta = 0;
@@ -2203,10 +2217,11 @@
static inline void
rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer,
- struct buffer_page *tail_page,
- unsigned long tail, unsigned long length)
+ unsigned long tail, struct rb_event_info *info)
{
+ struct buffer_page *tail_page = info->tail_page;
struct ring_buffer_event *event;
+ unsigned long length = info->length;
/*
* Only the event that crossed the page boundary
@@ -2276,13 +2291,14 @@
*/
static noinline struct ring_buffer_event *
rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
- unsigned long length, unsigned long tail,
- struct buffer_page *tail_page, u64 ts)
+ unsigned long tail, struct rb_event_info *info)
{
+ struct buffer_page *tail_page = info->tail_page;
struct buffer_page *commit_page = cpu_buffer->commit_page;
struct ring_buffer *buffer = cpu_buffer->buffer;
struct buffer_page *next_page;
int ret;
+ u64 ts;
next_page = tail_page;
@@ -2368,25 +2384,24 @@
out_again:
- rb_reset_tail(cpu_buffer, tail_page, tail, length);
+ rb_reset_tail(cpu_buffer, tail, info);
/* fail and let the caller try again */
return ERR_PTR(-EAGAIN);
out_reset:
/* reset write */
- rb_reset_tail(cpu_buffer, tail_page, tail, length);
+ rb_reset_tail(cpu_buffer, tail, info);
return NULL;
}
static struct ring_buffer_event *
__rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
- unsigned long length, u64 ts,
- u64 delta, int add_timestamp)
+ struct rb_event_info *info)
{
- struct buffer_page *tail_page;
struct ring_buffer_event *event;
+ struct buffer_page *tail_page;
unsigned long tail, write;
/*
@@ -2394,33 +2409,32 @@
* hold in the time field of the event, then we append a
* TIME EXTEND event ahead of the data event.
*/
- if (unlikely(add_timestamp))
- length += RB_LEN_TIME_EXTEND;
+ if (unlikely(info->add_timestamp))
+ info->length += RB_LEN_TIME_EXTEND;
- tail_page = cpu_buffer->tail_page;
- write = local_add_return(length, &tail_page->write);
+ tail_page = info->tail_page = cpu_buffer->tail_page;
+ write = local_add_return(info->length, &tail_page->write);
/* set write to only the index of the write */
write &= RB_WRITE_MASK;
- tail = write - length;
+ tail = write - info->length;
/*
* If this is the first commit on the page, then it has the same
* timestamp as the page itself.
*/
if (!tail)
- delta = 0;
+ info->delta = 0;
/* See if we shot pass the end of this buffer page */
if (unlikely(write > BUF_PAGE_SIZE))
- return rb_move_tail(cpu_buffer, length, tail,
- tail_page, ts);
+ return rb_move_tail(cpu_buffer, tail, info);
/* We reserved something on the buffer */
event = __rb_page_index(tail_page, tail);
kmemcheck_annotate_bitfield(event, bitfield);
- rb_update_event(cpu_buffer, event, length, add_timestamp, delta);
+ rb_update_event(cpu_buffer, event, info);
local_inc(&tail_page->entries);
@@ -2429,10 +2443,10 @@
* its timestamp.
*/
if (!tail)
- tail_page->page->time_stamp = ts;
+ tail_page->page->time_stamp = info->ts;
/* account for these added bytes */
- local_add(length, &cpu_buffer->entries_bytes);
+ local_add(info->length, &cpu_buffer->entries_bytes);
return event;
}
@@ -2521,9 +2535,8 @@
unsigned long length)
{
struct ring_buffer_event *event;
- u64 ts, delta;
+ struct rb_event_info info;
int nr_loops = 0;
- int add_timestamp;
u64 diff;
rb_start_commit(cpu_buffer);
@@ -2543,10 +2556,10 @@
}
#endif
- length = rb_calculate_event_length(length);
+ info.length = rb_calculate_event_length(length);
again:
- add_timestamp = 0;
- delta = 0;
+ info.add_timestamp = 0;
+ info.delta = 0;
/*
* We allow for interrupts to reenter here and do a trace.
@@ -2560,35 +2573,35 @@
if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000))
goto out_fail;
- ts = rb_time_stamp(cpu_buffer->buffer);
- diff = ts - cpu_buffer->write_stamp;
+ info.ts = rb_time_stamp(cpu_buffer->buffer);
+ diff = info.ts - cpu_buffer->write_stamp;
/* make sure this diff is calculated here */
barrier();
/* Did the write stamp get updated already? */
- if (likely(ts >= cpu_buffer->write_stamp)) {
- delta = diff;
- if (unlikely(test_time_stamp(delta))) {
+ if (likely(info.ts >= cpu_buffer->write_stamp)) {
+ info.delta = diff;
+ if (unlikely(test_time_stamp(info.delta))) {
int local_clock_stable = 1;
#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
local_clock_stable = sched_clock_stable();
#endif
- WARN_ONCE(delta > (1ULL << 59),
+ WARN_ONCE(info.delta > (1ULL << 59),
KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s",
- (unsigned long long)delta,
- (unsigned long long)ts,
+ (unsigned long long)info.delta,
+ (unsigned long long)info.ts,
(unsigned long long)cpu_buffer->write_stamp,
local_clock_stable ? "" :
"If you just came from a suspend/resume,\n"
"please switch to the trace global clock:\n"
" echo global > /sys/kernel/debug/tracing/trace_clock\n");
- add_timestamp = 1;
+ info.add_timestamp = 1;
}
}
- event = __rb_reserve_next(cpu_buffer, length, ts,
- delta, add_timestamp);
+ event = __rb_reserve_next(cpu_buffer, &info);
+
if (unlikely(PTR_ERR(event) == -EAGAIN))
goto again;
