Re: [PATCH net-next v4 3/3] eventpoll: Add epoll ioctl for epoll_params

Jiri Slaby
2024-01-31T06:03:59Z

On 31. 01. 24, 3:27, Joe Damato wrote:
> On Tue, Jan 30, 2024 at 06:08:36PM -0800, Greg Kroah-Hartman wrote:
>> On Wed, Jan 31, 2024 at 01:47:33AM +0000, Joe Damato wrote:
>>> +struct epoll_params {
>>> + __aligned_u64 busy_poll_usecs;
>>> + __u16 busy_poll_budget;
>>> +
>>> + /* pad the struct to a multiple of 64bits for alignment on all arches */
>>> + __u8 __pad[6];
>>
>> You HAVE to check this padding to be sure it is all 0, otherwise it can
>> never be used in the future for anything.
>
> Is there some preferred mechanism for this in the kernel that I should be
> using or is this as simple as adding a for loop to check each u8 == 0 ?

You are likely looking for memchr_inv().

--
js
suse labs