ftrace: Narrow down the protected area of graph_lock (6a10108b) · Commits · 戴 / test

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:

kernel/trace/ftrace.c

+9 −13

Original line number	Diff line number	Diff line
		@@ -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);
		}

		if (!ret)
		ret = read;

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

		return ret;
		}