Hello,
On 25/02/26 10:51, Gabriele Monaco wrote:
> Add the deadline monitors collection to validate the deadline scheduler,
> both for deadline tasks and servers.
>
> The currently implemented monitors are:
> * throttle:
> validate dl entities are throttled when they use up their runtime
> * nomiss:
> validate dl entities run to completion before their deadiline
>
> Cc: Peter Zijlstra <[email protected]>
> Reviewed-by: Nam Cao <[email protected]>
> Signed-off-by: Gabriele Monaco <[email protected]>
> ---
...
> +static inline int extract_params(struct pt_regs *regs, long id, struct
> task_struct **p)
> +{
> + size_t size = offsetof(struct sched_attr, sched_nice);
> + struct sched_attr __user *uattr, attr;
> + int new_policy = -1, ret;
> + unsigned long args[6];
> + pid_t pid;
> +
> + switch (id) {
> + case __NR_sched_setscheduler:
> + syscall_get_arguments(current, regs, args);
> + pid = args[0];
> + new_policy = args[1];
> + break;
> + case __NR_sched_setattr:
> + syscall_get_arguments(current, regs, args);
> + pid = args[0];
> + uattr = (void *)args[1];
> + /*
> + * Just copy up to sched_flags, we are not interested after that
> + */
> + ret = copy_struct_from_user(&attr, size, uattr, size);
> + if (ret)
> + return ret;
> + if (attr.sched_flags & SCHED_FLAG_KEEP_POLICY)
> + return -EINVAL;
> + new_policy = attr.sched_policy;
> + break;
> + default:
> + return -EINVAL;
> + }
> + if (!pid)
> + *p = current;
> + else {
> + /*
> + * Required for find_task_by_vpid, make sure the caller doesn't
> + * need to get_task_struct().
> + */
> + guard(rcu)();
> + *p = find_task_by_vpid(pid);
> + if (unlikely(!*p))
> + return -EINVAL;
> + }
Not sure I get this comment. RCU is released when the function returns,
but then the task pointer is dereferenced by callers?
Thanks,
Juri
