Re: [PATCH -tip v8 19/26] kprobes: Show blacklist entries via debugfs

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

(2014/03/25 5:19), Steven Rostedt wrote:
> On Wed, 05 Mar 2014 21:00:56 +0900
> Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:
> 
> 
>>  kernel/kprobes.c |   61 +++++++++++++++++++++++++++++++++++++++++++++++-------
>>  1 file changed, 53 insertions(+), 8 deletions(-)
>>
>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>> index a21b4e6..3214289 100644
>> --- a/kernel/kprobes.c
>> +++ b/kernel/kprobes.c
>> @@ -2249,6 +2249,46 @@ static const struct file_operations debugfs_kprobes_operations = {
>>  	.release        = seq_release,
>>  };
>>  
>> +/* kprobes/blacklist -- shows which functions can not be probed */
>> +static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
>> +{
>> +	return seq_list_start(&kprobe_blacklist, *pos);
>> +}
>> +
>> +static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
>> +{
>> +	return seq_list_next(v, &kprobe_blacklist, pos);
>> +}
>> +
> 
> Can modules use NOKPROBE_SYMBOL() and have items being added to the
> list as this is being read? That is, do we need locks?

At this point, no, the NOKPROBE_SYMBOL()s in module are just ignored.

> Also, are items removed. I need to go back and look at the
> implementation of NOKPROBE_SYMBOL(), I'm just writing this as I think
> about it ;-)

Actually, I've introduced a lock with module NOKPROBE_SYMBOL() support in
the next patch. :)
I'd like to split it because module blacklist support involves module
subsystem update.

Thank you!

-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com