lkml.org 
[lkml]   [2013]   [Aug]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC][PATCH 3/4] tracing/kprobes: Fail to unregister if probe event files are open
From
Date
On Thu, 2013-08-01 at 16:33 +0200, Oleg Nesterov wrote:
> On 08/01, Steven Rostedt wrote:
> >
> > On Thu, 2013-08-01 at 15:34 +0200, Oleg Nesterov wrote:
> > > >
> > > > __unregister_trace_probe(tp);
> > > > list_del(&tp->list)
> > > > unregister_probe_event(tp) <-- fails!
> > > > free_trace_probe(tp)
> > >
> > > Yes. But again, this doesn't explain why unregister_probe_event()->
> > > __trace_remove_event_call() can't simply proceed and
> > > do ftrace_event_enable_disable() + remove_event_from_tracers().
> >
> > The problem is with the soft disable.
>
> Exactly! This is another (also unlikely) race we need to prevent.
>

Is there a race even with these patches? I don't see one. To link a
function to an event (set the soft disable mode), the event_mutex is
taken. If the event is gone, it wont be able to link. If the soft
disable is attached (after found and set under event_mutex), the event
can't be deleted.

Or are you just saying that these patches fix that case too?

-- Steve




\
 
 \ /
  Last update: 2013-08-01 19:01    [W:0.052 / U:0.892 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site