Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH 11/11] svcgssd: Wait for nullrpc channel if not available
To:     "J. Bruce Fields" <bfields@fieldses.org>
Cc:     linux-nfs@vger.kernel.org
References: <20200718092421.31691-1-nazard@nazar.ca>
 <20200718092421.31691-12-nazard@nazar.ca>
 <20200718155501.GB27817@fieldses.org>
From:   Doug Nazar <nazard@nazar.ca>
Message-ID: <3b9a70ce-f1b4-da68-cfc1-8e93af197461@nazar.ca>
Date:   Sat, 18 Jul 2020 14:07:37 -0400
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101
 Firefox/78.0 Thunderbird/78.0
MIME-Version: 1.0
In-Reply-To: <20200718155501.GB27817@fieldses.org>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Sender: linux-nfs-owner@vger.kernel.org
Precedence: bulk

On 2020-07-18 11:55, J. Bruce Fields wrote:

> So, is there a race here that could result in a hang, and has anyone
> seen it in practice?
>
> Just curious.  Thanks for doing this.--b.

Not a hang, with the existing code, svcgssd will just exit. I'd have to 
go and restart it after boot. I'm assuming a systemd setup would just 
restart it automatically.
On my original systems I'd configured it to force load the modules, but 
I'd forgotten about that (it was about 10 years ago) when I built this 
new box last month.

As mentioned in the other email, sunrpc is loaded from an initramfs that 
doesn't have any of the gss modules. When nfsd is started (after 
svcgssd) it'll then load the gss modules but by then it's too late.

It seems to be a standard Gentoo setup. I just checked the default 
kernel config for genkernel (their kernel & initramfs builder) and it 
has all the rpc & nfs as modules, with the initramfs not supporting 
Kerberos.

Looks like Debian modprobes rpcsec_gss_krb5 before starting rpc.svcgssd.

So with this waiting for the file to appear, and I'm planning on adding 
a conditional module load to the Gentoo rpc.svcgssd init script, things 
should be as bulletproof as I can make it.

Doug