From: Jim Rees <rees@umich.edu>
To: Chuck Lever <chuck.lever@oracle.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>,
Jeff Layton <jlayton@redhat.com>,
linux-nfs@vger.kernel.org
Subject: Re: [PATCH v3 2/2] nfsd: keep a checksum of the first 256 bytes of request
Date: Thu, 7 Feb 2013 11:41:24 -0500 [thread overview]
Message-ID: <20130207164124.GA4522@umich.edu> (raw)
In-Reply-To: <7AE3520E-0F1E-4BDF-9977-B110180E99E3@oracle.com>
Chuck Lever wrote:
>
>> I'm wondering if a simpler checksum might be just as useful but less
>> costly to compute.
>
> What would be an example of a simpler checksum?
The same one TCP uses, like a simple additive sum, or an XOR. Is a
heavyweight checksum needed because checksums generated with a simple
function are more likely to collide?
At least CRC isn't as bad as a crypto checksum like md5. Those are often
misused when what's really wanted is just a simple guard against accidental
corruption. In this case I'd go with the tcp checksum, which I think has an
api and even an accelerated implementation depending on the machine arch,
although I can't find it right now.
next prev parent reply other threads:[~2013-02-07 16:41 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-07 14:51 [PATCH v3 0/2] nfsd: checksum first 256 bytes of request to guard against XID collisions in the DRC Jeff Layton
2013-02-07 14:51 ` [PATCH v3 1/2] sunrpc: trim off trailing checksum before returning decrypted or integrity authenticated buffer Jeff Layton
2013-02-07 14:51 ` [PATCH v3 2/2] nfsd: keep a checksum of the first 256 bytes of request Jeff Layton
2013-02-07 15:51 ` Chuck Lever
2013-02-07 16:00 ` J. Bruce Fields
2013-02-07 16:23 ` Chuck Lever
2013-02-07 16:37 ` J. Bruce Fields
2013-02-07 16:41 ` Jim Rees [this message]
2013-02-07 16:32 ` Myklebust, Trond
2013-02-07 18:35 ` Jeff Layton
2013-02-08 15:41 ` Jeff Layton
2013-02-07 18:03 ` Jeff Layton
2013-02-08 13:27 ` Jeff Layton
2013-02-08 15:42 ` Chuck Lever
2013-02-08 15:57 ` Jeff Layton
2013-02-08 20:55 ` J. Bruce Fields
2013-02-08 20:59 ` Chuck Lever
2013-02-08 21:02 ` J. Bruce Fields
2013-02-09 11:36 ` Jeff Layton
2013-02-07 15:11 ` [PATCH v3 0/2] nfsd: checksum first 256 bytes of request to guard against XID collisions in the DRC J. Bruce Fields
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