On Thu, Jun 28, 2018 at 11:21:46AM -0700, Joel Fernandes wrote:
> static inline void tracepoint_synchronize_unregister(void)
> {
> + synchronize_srcu(&tracepoint_srcu);
> synchronize_sched();
> }
Given you below do call_rcu_sched() and then call_srcu(), isn't the
above the wrong way around?
Also, does the above want to be barrier instead of synchronize, so as to
guarantee completion of the callbacks.
> +static void srcu_free_old_probes(struct rcu_head *head)
> {
> kfree(container_of(head, struct tp_probes, rcu));
> }
>
> +static void rcu_free_old_probes(struct rcu_head *head)
> +{
> + call_srcu(&tracepoint_srcu, head, srcu_free_old_probes);
> +}
> +
> static inline void release_probes(struct tracepoint_func *old)
> {
> if (old) {
> struct tp_probes *tp_probes = container_of(old,
> struct tp_probes, probes[0]);
> + /*
> + * Tracepoint probes are protected by both sched RCU and SRCU,
> + * by calling the SRCU callback in the sched RCU callback we
> + * cover both cases. So let us chain the SRCU and sched RCU
> + * callbacks to wait for both grace periods.
> + */
> call_rcu_sched(&tp_probes->rcu, rcu_free_old_probes);
> }
> }
