Re: [RFC][PATCH 04/10] futex: Add sys_futex_wake()

[Arnd Bergmann]

On Fri, Jul 14, 2023, at 15:39, Peter Zijlstra wrote:
>
> +++ b/include/linux/syscalls.h
> @@ -563,6 +563,9 @@ asmlinkage long sys_set_robust_list(stru
>  asmlinkage long sys_futex_waitv(struct futex_waitv *waiters,
>  				unsigned int nr_futexes, unsigned int flags,
>  				struct __kernel_timespec __user *timeout, clockid_t clockid);
> +
> +asmlinkage long sys_futex_wake(void __user *uaddr, int nr, unsigned 
> int flags, u64 mask);
> +

You can't really use 'u64' arguments in portable syscalls, it causes
a couple of problems, both with defining the user space wrappers,
and with compat mode.

Variants that would work include:

- using 'unsigned long' instead of 'u64'
- passing 'mask' by reference, as in splice()
- passing the mask in two u32-bit arguments like in llseek()

Not sure if any of the above work for you.

       Arnd