lkml.org 
[lkml]   [2013]   [Aug]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v7 01/10] tracing: Add support for SOFT_DISABLE to syscall events
From
Date
On Tue, 2013-08-27 at 16:08 -0400, Steven Rostedt wrote:
> On Tue, 27 Aug 2013 14:40:13 -0500
> Tom Zanussi <tom.zanussi@linux.intel.com> wrote:
>
> > @@ -415,9 +429,14 @@ static void unreg_event_syscall_enter(struct ftrace_event_file *file,
> > return;
> > mutex_lock(&syscall_trace_lock);
> > tr->sys_refcount_enter--;
> > - clear_bit(num, tr->enabled_enter_syscalls);
> > + rcu_assign_pointer(tr->enter_syscall_files[num], NULL);
> > if (!tr->sys_refcount_enter)
> > unregister_trace_sys_enter(ftrace_syscall_enter, tr);
> > + /*
> > + * Callers expect the event to be completely disabled on
> > + * return, so wait for current handlers to finish.
> > + */
> > + synchronize_sched();
> > mutex_unlock(&syscall_trace_lock);
> > }
> >
> > @@ -435,7 +454,7 @@ static int reg_event_syscall_exit(struct ftrace_event_file *file,
> > if (!tr->sys_refcount_exit)
> > ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
> > if (!ret) {
> > - set_bit(num, tr->enabled_exit_syscalls);
> > + rcu_assign_pointer(tr->exit_syscall_files[num], file);
> > tr->sys_refcount_exit++;
> > }
> > mutex_unlock(&syscall_trace_lock);
> > @@ -453,9 +472,14 @@ static void unreg_event_syscall_exit(struct ftrace_event_file *file,
> > return;
> > mutex_lock(&syscall_trace_lock);
> > tr->sys_refcount_exit--;
> > - clear_bit(num, tr->enabled_exit_syscalls);
> > + rcu_assign_pointer(tr->exit_syscall_files[num], NULL);
> > if (!tr->sys_refcount_exit)
> > unregister_trace_sys_exit(ftrace_syscall_exit, tr);
> > + /*
> > + * Callers expect the event to be completely disabled on
> > + * return, so wait for current handlers to finish.
> > + */
> > + synchronize_sched();
> > mutex_unlock(&syscall_trace_lock);
>
> Can we do the synchronize_sched() after the mutex unlock in these two
> places?
>

Yeah, I think that should be ok and there should be no need to delay
waiters for that mutex - I'll look at moving it out for the next
revision.

Thanks,

Tom

> -- Steve
>
>
> > }
> >
>




\
 
 \ /
  Last update: 2013-08-28 02:01    [W:0.054 / U:0.092 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site