linux-kernel - Re: linux-next: build failure after merge of the nfsd tree

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Message-Id: <BD32EC01-EA3A-403C-A8D2-904B77EB79BA@oracle.com>
Date:	Mon, 29 Apr 2013 13:47:16 -0400
From:	Chuck Lever <chuck.lever@...cle.com>
To:	"J. Bruce Fields" <bfields@...ldses.org>
Cc:	Trond Myklebust <trond.myklebust@....uio.no>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-next@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Simo Sorce <simo@...hat.com>
Subject: Re: linux-next: build failure after merge of the nfsd tree


On Apr 29, 2013, at 1:38 PM, "J. Bruce Fields" <bfields@...ldses.org> wrote:

> On Mon, Apr 29, 2013 at 01:04:01PM -0400, Chuck Lever wrote:
>> 
>> On Apr 29, 2013, at 12:21 PM, Trond Myklebust
>> <trond.myklebust@....uio.no> wrote:
>> 
>>> On Mon, 2013-04-29 at 12:05 -0400, Chuck Lever wrote:
>>>> On Apr 29, 2013, at 11:45 AM, "J. Bruce Fields"
>>>> <bfields@...ldses.org> wrote:
>>>> 
>>>>> On Mon, Apr 29, 2013 at 10:53:37AM -0400, Chuck Lever wrote:
>>>>>> 
>>>>>> On Apr 28, 2013, at 9:24 PM, Stephen Rothwell
>>>>>> <sfr@...b.auug.org.au> wrote:
>>>>>> 
>>>>>>> Hi J.,
>>>>>>> 
>>>>>>> After merging the nfsd tree, today's linux-next build (powerpc
>>>>>>> ppc64_defconfig) failed like this:
>>>>>>> 
>>>>>>> net/sunrpc/auth_gss/svcauth_gss.c: In function
>>>>>>> 'gss_proxy_save_rsc': net/sunrpc/auth_gss/svcauth_gss.c:1182:3:
>>>>>>> error: implicit declaration of function 'gss_mech_get_by_OID'
>>>>>>> [-Werror=implicit-function-declaration]
>>>>>>> 
>>>>>>> Caused byc ommit 030d794bf498 ("SUNRPC: Use gssproxy upcall for
>>>>>>> server RPCGSS authentication").  gss_mech_get_by_OID() made
>>>>>>> static to net/sunrpc/auth_gss/gss_mech_switch.c by commit
>>>>>>> 9568c5e9a61d ("SUNRPC: Introduce rpcauth_get_pseudoflavor()") in
>>>>>>> the nfs tree (part of the nfs tree that you did not merge).
>>>>>>> 
>>>>>>> I don't know how to fix this, so I have used the nfsd tree from
>>>>>>> next-20130426 for today.
>>>>>> 
>>>>>> Bruce, it might make sense for me to submit the three server-side
>>>>>> RPC GSS patches, and then you can rebase the gssproxy work on top
>>>>>> of those.  Let me know how you would like to proceed.
>>>>> 
>>>>> I'm happy to take those patches whenever you consider them ready.
>>>>> Would that fix the problem?
>>>> 
>>>> Someone would need to modify the gssproxy patches to use the new
>>>> interfaces.
>>>> 
>>>>> Also: it looks like 030d794bf498 "SUNRPC: Introduce
>>>>> rpcauth_get_pseudoflavor()" is in Trond's linux-next, but not his
>>>>> nfs-for-next.  I'm not sure what that means--is it safe to rebase
>>>>> on top of *that*?
>>>> 
>>>> That doesn't seem right to me.
>>> 
>>> I've now pulled the rpcsec_gss changes into the nfs-for-next. The
>>> main reason why they were not pulled in earlier was due to
>>> uncertainty what to do about the increase in "AUTH_GSS upcall timed
>>> out." syslog warnings.
>> 
>> Trond's nfs-for-next now has the new rpcauth_get_gssinfo() and
>> rpcauth_get_pseudoflavor() APIs, which are replacements for direct
>> calls into the GSS mech switch.  These APIs are a little more generic,
>> and more robust in the face of unloaded GSS kernel modules.
>> 
>> Instead of gss_mech_get_by_OID(), I suspect you want
>> rpcauth_get_pseudoflavor(), but I haven't looked at the gssproxy code.
> 
> It's doing
> 
> 		status = -EOPNOTSUPP;
> 		gm = gss_mech_get_by_OID(&ud->mech_oid);
> 		if (!gm)
> 			goto out;
> 		status = -EINVAL;
> 		status = gss_import_sec_context(ud->out_handle.data,
> 						ud->out_handle.len,
> 						gm, &rsci.mechctx,
> 						&expiry, GFP_KERNEL);
> 		if (status)
> 			goto out;
> 
> So we need a way to get from an OID and some mechanism-specific data to
> a context.
> 
> Looks to me like we just want to re-export gss_mech_get_by_OID().

The reason for the new wrappers is to load the kernel modules properly before trying to discover the OID -> mechanism mapping.

Where are you calling it from?  If it's from outside of the GSS module, how do you guarantee the rpc_gss_auth module is loaded?  What if the GSS mechanism for that OID isn't loaded?

-- 
Chuck Lever
chuck[dot]lever[at]oracle[dot]com




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