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Subject[for-next][PATCH 5/6] ftrace: Narrow down the protected area of graph_lock
From: Namhyung Kim <namhyung.kim@lge.com>

The parser set up is just a generic utility that uses local variables
allocated by the function. There's no need to hold the graph_lock for
this set up.

This also makes the code simpler.

Link: http://lkml.kernel.org/r/1381739066-7531-4-git-send-email-namhyung@kernel.org

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0ff3449..26a229a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3973,37 +3973,33 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_parser parser;
- ssize_t read, ret;
+ ssize_t read, ret = 0;
struct ftrace_graph_data *fgd = file->private_data;

if (!cnt)
return 0;

- mutex_lock(&graph_lock);
-
- if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX)) {
- ret = -ENOMEM;
- goto out_unlock;
- }
+ if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX))
+ return -ENOMEM;

read = trace_get_user(&parser, ubuf, cnt, ppos);

if (read >= 0 && trace_parser_loaded((&parser))) {
parser.buffer[parser.idx] = 0;

+ mutex_lock(&graph_lock);
+
/* we allow only one expression at a time */
ret = ftrace_set_func(fgd->table, fgd->count, fgd->size,
parser.buffer);
- if (ret)
- goto out_free;
+
+ mutex_unlock(&graph_lock);
}

- ret = read;
+ if (!ret)
+ ret = read;

-out_free:
trace_parser_put(&parser);
-out_unlock:
- mutex_unlock(&graph_lock);

return ret;
}
--
1.8.4.rc3



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