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tracing: Turn event/id->i_private into call->event.type

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commit 1a11126bcb upstream.

event_id_read() is racy, ftrace_event_call can be already freed
by trace_remove_event_call() callers.

Change event_create_dir() to pass "data = call->event.type", this
is all event_id_read() needs. ftrace_event_id_fops no longer needs
tracing_open_generic().

We add the new helper, event_file_data(), to read ->i_private, it
will have more users.

Note: currently ACCESS_ONCE() and "id != 0" check are not needed,
but we are going to change event_remove/rmdir to clear ->i_private.

Link: http://lkml.kernel.org/r/20130726172532.GA3605@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oleg Nesterov
2013-07-26 19:25:32 +02:00
committed by Greg Kroah-Hartman
parent 29632b10ef
commit fdb65fe265
1 changed files with 12 additions and 5 deletions
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17
kernel/trace/trace_events.c
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@@ -407,6 +407,11 @@ static void put_system(struct ftrace_subsystem_dir *dir)
mutex_unlock(&event_mutex);
}
static void *event_file_data(struct file *filp)
{
return ACCESS_ONCE(file_inode(filp)->i_private);
}
/*
* Open and update trace_array ref count.
* Must have the current trace_array passed to it.
@@ -960,19 +965,22 @@ static int trace_format_open(struct inode *inode, struct file *file)
static ssize_t
event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
{
struct ftrace_event_call *call = filp->private_data;
int id = (long)event_file_data(filp);
struct trace_seq *s;
int r;
if (*ppos)
return 0;
if (unlikely(!id))
return -ENODEV;
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
trace_seq_init(s);
trace_seq_printf(s, "%d\n", call->event.type);
trace_seq_printf(s, "%d\n", id);
r = simple_read_from_buffer(ubuf, cnt, ppos,
s->buffer, s->len);
@@ -1263,7 +1271,6 @@ static const struct file_operations ftrace_event_format_fops = {
};
static const struct file_operations ftrace_event_id_fops = {
.open = tracing_open_generic,
.read = event_id_read,
.llseek = default_llseek,
};
@@ -1511,8 +1518,8 @@ event_create_dir(struct dentry *parent,
#ifdef CONFIG_PERF_EVENTS
if (call->event.type && call->class->reg)
trace_create_file("id", 0444, file->dir, call,
id);
trace_create_file("id", 0444, file->dir,
(void *)(long)call->event.type, id);
#endif
/*