* Masami Hiramatsu <[email protected]> wrote:
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -377,6 +377,23 @@ static inline void copy_kprobe(struct kprobe *ap, struct
> kprobe *p)
> static bool kprobes_allow_optimization;
>
> /*
> + * Synchronizing wait on trampline code for interrupted tasks/threads.
> + * Since the threads running on dynamically allocated trampline code
> + * can be interrupted, kprobes has to wait for those tasks back on
> + * track and scheduled. If the kernel is preemptive, the thread can be
> + * preempted by other tasks on the trampoline too. For such case, this
> + * calls synchronize_rcu_tasks() to wait for those tasks back on track.
> + */
> +static void synchronize_on_trampoline(void)
> +{
> +#ifdef CONFIG_PREEMPT
> + synchronize_rcu_tasks();
> +#else
> + synchronize_sched();
> +#endif
> +}
So that's really unacceptably ugly.
Paul, I still question the need to have tasks-RCU as a Kconfig distinction,
_especially_ if its API usage results in such ugly secondary #ifdefs...
Why isn't there a single synchronize_rcu_tasks() API function, which does what
is
expected, where the _RCU_ code figures out how to implement it?
I.e.:
- There should be no user configurable TASKS_RCU Kconfig setting - at most a
helper Kconfig that is automatically selected by the RCU code itself.
- Both ftrace andkprobes would use a simple synchronize_rcu_tasks() call.
Thanks,
Ingo
