tracing: pass around ring buffer instead of tracer
The latency tracers (irqsoff and wakeup) can swap trace buffers
on the fly. If an event is happening and has reserved data on one of
the buffers, and the latency tracer swaps the global buffer with the
max buffer, the result is that the event may commit the data to the
wrong buffer.
This patch changes the API to the trace recording to be recieve the
buffer that was used to reserve a commit. Then this buffer can be passed
in to the commit.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 1090b0a..243bafc 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -65,13 +65,15 @@
{
struct blk_io_trace *t;
struct ring_buffer_event *event = NULL;
+ struct ring_buffer *buffer = NULL;
int pc = 0;
int cpu = smp_processor_id();
bool blk_tracer = blk_tracer_enabled;
if (blk_tracer) {
+ buffer = blk_tr->buffer;
pc = preempt_count();
- event = trace_buffer_lock_reserve(blk_tr, TRACE_BLK,
+ event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
sizeof(*t) + len,
0, pc);
if (!event)
@@ -96,7 +98,7 @@
memcpy((void *) t + sizeof(*t), data, len);
if (blk_tracer)
- trace_buffer_unlock_commit(blk_tr, event, 0, pc);
+ trace_buffer_unlock_commit(buffer, event, 0, pc);
}
}
@@ -179,6 +181,7 @@
{
struct task_struct *tsk = current;
struct ring_buffer_event *event = NULL;
+ struct ring_buffer *buffer = NULL;
struct blk_io_trace *t;
unsigned long flags = 0;
unsigned long *sequence;
@@ -204,8 +207,9 @@
if (blk_tracer) {
tracing_record_cmdline(current);
+ buffer = blk_tr->buffer;
pc = preempt_count();
- event = trace_buffer_lock_reserve(blk_tr, TRACE_BLK,
+ event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
sizeof(*t) + pdu_len,
0, pc);
if (!event)
@@ -252,7 +256,7 @@
memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
if (blk_tracer) {
- trace_buffer_unlock_commit(blk_tr, event, 0, pc);
+ trace_buffer_unlock_commit(buffer, event, 0, pc);
return;
}
}