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Commit 8650ae32 authored Jul 22, 2009 by Steven Rostedt Committed by Steven Rostedt Jul 23, 2009

tracing: only truncate ftrace files when O_TRUNC is set



The current code will truncate the ftrace files contents if O_APPEND
is not set and the file is opened in write mode. This is incorrect.
It should only truncate the file if O_TRUNC is set. Otherwise
if one of these files is opened by a C program with fopen "r+",
it will incorrectly truncate the file.

Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

parent 4c739ff0

kernel/trace/ftrace.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1662,7 +1662,7 @@ ftrace_regex_open(struct inode inode, struct file file, int enable)

		mutex_lock(&ftrace_regex_lock);
		if ((file->f_mode & FMODE_WRITE) &&
		!(file->f_flags & O_APPEND))
		(file->f_flags & O_TRUNC))
		ftrace_filter_reset(enable);

		if (file->f_mode & FMODE_READ) {
		@@ -2577,7 +2577,7 @@ ftrace_graph_open(struct inode inode, struct file file)

		mutex_lock(&graph_lock);
		if ((file->f_mode & FMODE_WRITE) &&
		!(file->f_flags & O_APPEND)) {
		(file->f_flags & O_TRUNC)) {
		ftrace_graph_count = 0;
		memset(ftrace_graph_funcs, 0, sizeof(ftrace_graph_funcs));
		}

kernel/trace/trace.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2031,7 +2031,7 @@ static int tracing_open(struct inode inode, struct file file)

		/* If this file was open for write, then erase contents */
		if ((file->f_mode & FMODE_WRITE) &&
		!(file->f_flags & O_APPEND)) {
		(file->f_flags & O_TRUNC)) {
		long cpu = (long) inode->i_private;

		if (cpu == TRACE_PIPE_ALL_CPU)

kernel/trace/trace_events.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -376,7 +376,7 @@ ftrace_event_seq_open(struct inode inode, struct file file)
		const struct seq_operations *seq_ops;

		if ((file->f_mode & FMODE_WRITE) &&
		!(file->f_flags & O_APPEND))
		(file->f_flags & O_TRUNC))
		ftrace_clear_events();

		seq_ops = inode->i_private;