linux-kernel - Re: [PATCH] nfs: add missing selections of CONFIG

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Message-ID: <81c2935a-7bb6-4d56-badc-705b60dd1169@oracle.com>
Date: Wed, 9 Apr 2025 09:39:08 -0400
From: Chuck Lever <chuck.lever@...cle.com>
To: Eric Biggers <ebiggers@...nel.org>
Cc: linux-nfs@...r.kernel.org, Trond Myklebust <trondmy@...nel.org>,
        Anna Schumaker <anna@...nel.org>, Jeff Layton <jlayton@...nel.org>,
        Neil Brown <neilb@...e.de>, Olga Kornievskaia <okorniev@...hat.com>,
        Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>,
        Ard Biesheuvel <ardb@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfs: add missing selections of CONFIG_CRC32

On 4/8/25 4:45 PM, Eric Biggers wrote:
> On Wed, Apr 02, 2025 at 09:29:41AM -0700, Eric Biggers wrote:
>> On Wed, Apr 02, 2025 at 09:51:05AM -0400, Chuck Lever wrote:
>>> On 4/1/25 6:02 PM, Eric Biggers wrote:
>>>> From: Eric Biggers <ebiggers@...gle.com>
>>>>
>>>> nfs.ko, nfsd.ko, and lockd.ko all use crc32_le(), which is available
>>>> only when CONFIG_CRC32 is enabled.  But the only NFS kconfig option that
>>>> selected CONFIG_CRC32 was CONFIG_NFS_DEBUG, which is client-specific and
>>>> did not actually guard the use of crc32_le() even on the client.
>>>>
>>>> The code worked around this bug by only actually calling crc32_le() when
>>>> CONFIG_CRC32 is built-in, instead hard-coding '0' in other cases.  This
>>>> avoided randconfig build errors, and in real kernels the fallback code
>>>> was unlikely to be reached since CONFIG_CRC32 is 'default y'.  But, this
>>>> really needs to just be done properly, especially now that I'm planning
>>>> to update CONFIG_CRC32 to not be 'default y'.
>>>
>>> It's interesting that no-one has noticed this before. dprintk is not the
>>> only consumer of the FH hash function: NFS/NFSD trace points also use
>>> it.
>>>
>>> Eric, assuming you would like to carry this patch forward instead of us
>>> taking it through one of the NFS client or server trees:
>>>
>>> Acked-by: Chuck Lever <chuck.lever@...cle.com>
>>>
>>> for the hunks related to nfsd and lockd.
>>
>> Please go ahead and take it through one of the NFS trees.  Thanks!
>>
> 
> I ended up sending in the removal of 'default y' from CONFIG_CRC32 for 6.15.  So
> I recommend that you send this NFS patch in for 6.15 as well, as it's now
> slightly more likely that people can end up with CONFIG_CRC32 disabled (though
> many other parts of the kernel select it anyway, so it still tends to be
> enabled).

I've moved the patch to nfsd-next, which has exposure to community
automated testing robots. If no problems are reported, I will move the
patch to nfsd-fixes and push it to v6.15-rc in a couple of weeks.


-- 
Chuck Lever