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Date: Tue, 30 Jan 2024 18:31:58 -0800
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Joe Damato <jdamato@fastly.com>
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Subject: Re: [PATCH net-next v4 3/3] eventpoll: Add epoll ioctl for
 epoll_params
Message-ID: <2024013045-manifesto-each-cbdc@gregkh>
References: <20240131014738.469858-1-jdamato@fastly.com>
 <20240131014738.469858-4-jdamato@fastly.com>
 <2024013001-prison-strum-899d@gregkh>
 <20240131022756.GA4837@fastly.com>
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In-Reply-To: <20240131022756.GA4837@fastly.com>

On Tue, Jan 30, 2024 at 06:27:57PM -0800, 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 ?

It's as simple as a loop :)