On Tue, 27 Aug 2013 14:40:13 -0500
Tom Zanussi <tom.zanu...@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?
-- Steve
> }
>
--
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