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Subject[PATCH 2/2] [PATCH 2/2] tracing: user local buffer variable for trace branch tracer
From: Steven Rostedt <srostedt@redhat.com>

Just using the tr->buffer for the API to trace_buffer_lock_reserve
is not good enough. This is because the tr->buffer may change, and we
do not want to commit with a different buffer that we reserved from.

This patch uses a local variable to hold the buffer that was used to
reserve and commit with.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_branch.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index 216e2dd..4a194f0 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -34,6 +34,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
struct trace_array *tr = branch_tracer;
struct ring_buffer_event *event;
struct trace_branch *entry;
+ struct ring_buffer *buffer;
unsigned long flags;
int cpu, pc;
const char *p;
@@ -54,7 +55,8 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
goto out;

pc = preempt_count();
- event = trace_buffer_lock_reserve(tr->buffer, TRACE_BRANCH,
+ buffer = tr->buffer;
+ event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH,
sizeof(*entry), flags, pc);
if (!event)
goto out;
@@ -74,8 +76,8 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
entry->line = f->line;
entry->correct = val == expect;

- if (!filter_check_discard(call, entry, tr->buffer, event))
- ring_buffer_unlock_commit(tr->buffer, event);
+ if (!filter_check_discard(call, entry, buffer, event))
+ ring_buffer_unlock_commit(buffer, event);

out:
atomic_dec(&tr->data[cpu]->disabled);
--
1.6.3.3



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