Finally change f_start() to take event_mutex and verify i_private, f_stop() drops this lock. This closes the races with event_remove.
Note: the usage of event_mutex is sub-optimal but simple, we can change this later. Signed-off-by: Oleg Nesterov <[email protected]> --- kernel/trace/trace_events.c | 17 +++++++++++++---- 1 files changed, 13 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 6c3e4e6..dc6c1ee 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -805,7 +805,8 @@ enum { static void *f_next(struct seq_file *m, void *v, loff_t *pos) { - struct ftrace_event_call *call = m->private; + struct inode *inode = m->private; + struct ftrace_event_call *call = inode->i_private; struct list_head *common_head = &ftrace_common_fields; struct list_head *head = trace_get_fields(call); struct list_head *node = v; @@ -837,7 +838,8 @@ 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 inode *inode = m->private; + struct ftrace_event_call *call = inode->i_private; struct ftrace_event_field *field; const char *array_descriptor; @@ -887,9 +889,16 @@ static int f_show(struct seq_file *m, void *v) static void *f_start(struct seq_file *m, loff_t *pos) { + struct inode *inode = m->private; void *p = (void *)FORMAT_HEADER; loff_t l = 0; + mutex_lock(&event_mutex); + if (unlikely(!inode->i_private)) { + mutex_unlock(&event_mutex); + return ERR_PTR(-ENODEV); + } + while (p && l < *pos) p = f_next(m, p, &l); @@ -898,6 +907,7 @@ 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 = { @@ -909,7 +919,6 @@ 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; @@ -918,7 +927,7 @@ static int trace_format_open(struct inode *inode, struct file *file) return ret; m = file->private_data; - m->private = call; + m->private = inode; return 0; } -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
