lkml.org 
[lkml]   [2013]   [Jul]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 1/1] tracing: Simplify trace_array_get()
trace_array_get() scans the global ftrace_trace_arrays list
to ensure that "this_tr" was not removed by instance_delete().

This looks a bit confusing, we can simply use list_empty() with
the same result. list_empty() == F can not be false positive,
new_instance_create() does everything under the same lock and
tracer_alloc_buffers() which plays with global_trace is __init.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/trace/trace.c | 12 ++++--------
1 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0cd500b..ee471fb 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -206,16 +206,12 @@ LIST_HEAD(ftrace_trace_arrays);

int trace_array_get(struct trace_array *this_tr)
{
- struct trace_array *tr;
int ret = -ENODEV;

mutex_lock(&trace_types_lock);
- list_for_each_entry(tr, &ftrace_trace_arrays, list) {
- if (tr == this_tr) {
- tr->ref++;
- ret = 0;
- break;
- }
+ if (!list_empty(&this_tr->list)) {
+ this_tr->ref++;
+ ret = 0;
}
mutex_unlock(&trace_types_lock);

@@ -6019,7 +6015,7 @@ static int instance_delete(const char *name)
if (tr->ref)
goto out_unlock;

- list_del(&tr->list);
+ list_del_init(&tr->list); /* trace_array_get() checks list_empty() */

event_trace_del_tracer(tr);
debugfs_remove_recursive(tr->dir);
--
1.5.5.1



\
 
 \ /
  Last update: 2013-07-19 18:21    [W:0.056 / U:0.384 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site