diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2013-07-26 19:25:43 +0200 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2013-07-29 22:57:10 -0400 |
| commit | c5a44a1200c6eda2202434f25325e8ad19533fca (patch) | |
| tree | 4ac8699d7e7ce648d888a2f2fb4889380d9b02a6 /kernel | |
| parent | e2912b091c26b8ea95e5e00a43a7ac620f6c94a6 (diff) | |
tracing: Change f_start() to take event_mutex and verify i_private != NULL
trace_format_open() and trace_format_seq_ops are racy, nothing
protects ftrace_event_call from trace_remove_event_call().
Change f_start() to take event_mutex and verify i_private != NULL,
change f_stop() to drop this lock.
This fixes nothing, but now we can change debugfs_remove("format")
callers to nullify ->i_private and fix the the problem.
Note: the usage of event_mutex is sub-optimal but simple, we can
change this later.
Link: http://lkml.kernel.org/r/20130726172543.GA3622@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_events.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 1d7b6d03cd51..50dc8b2e5435 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -840,7 +840,7 @@ enum { static void *f_next(struct seq_file *m, void *v, loff_t *pos) { - struct ftrace_event_call *call = m->private; + struct ftrace_event_call *call = event_file_data(m->private); struct list_head *common_head = &ftrace_common_fields; struct list_head *head = trace_get_fields(call); struct list_head *node = v; @@ -872,7 +872,7 @@ static void *f_next(struct seq_file *m, void *v, loff_t *pos) static int f_show(struct seq_file *m, void *v) { - struct ftrace_event_call *call = m->private; + struct ftrace_event_call *call = event_file_data(m->private); struct ftrace_event_field *field; const char *array_descriptor; @@ -925,6 +925,11 @@ static void *f_start(struct seq_file *m, loff_t *pos) void *p = (void *)FORMAT_HEADER; loff_t l = 0; + /* ->stop() is called even if ->start() fails */ + mutex_lock(&event_mutex); + if (!event_file_data(m->private)) + return ERR_PTR(-ENODEV); + while (l < *pos && p) p = f_next(m, p, &l); @@ -933,6 +938,7 @@ static void *f_start(struct seq_file *m, loff_t *pos) static void f_stop(struct seq_file *m, void *p) { + mutex_unlock(&event_mutex); } static const struct seq_operations trace_format_seq_ops = { @@ -944,7 +950,6 @@ static const struct seq_operations trace_format_seq_ops = { static int trace_format_open(struct inode *inode, struct file *file) { - struct ftrace_event_call *call = inode->i_private; struct seq_file *m; int ret; @@ -953,7 +958,7 @@ static int trace_format_open(struct inode *inode, struct file *file) return ret; m = file->private_data; - m->private = call; + m->private = file; return 0; } |