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Message-ID: <efee9789-4f05-4202-9a95-21d88f6307b0@kernel.org>
Date: Wed, 31 Jan 2024 07:03:54 +0100
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Subject: Re: [PATCH net-next v4 3/3] eventpoll: Add epoll ioctl for
 epoll_params
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To: Joe Damato <jdamato@fastly.com>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
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References: <20240131014738.469858-1-jdamato@fastly.com>
 <20240131014738.469858-4-jdamato@fastly.com>
 <2024013001-prison-strum-899d@gregkh> <20240131022756.GA4837@fastly.com>
From: Jiri Slaby <jirislaby@kernel.org>
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In-Reply-To: <20240131022756.GA4837@fastly.com>
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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