tun: Optimise handling of bogus gso->hdr_len

Submitted by Herbert Xu on June 4, 2009, 11:06 a.m.

Details

Message ID 20090604110600.GA28453@gondor.apana.org.au
State Accepted
Delegated to: David Miller
Headers show

Commit Message

Herbert Xu June 4, 2009, 11:06 a.m.
Hi:

tun: Optimise handling of bogus gso->hdr_len

As all current versions of virtio_net generate a value for the
header length that's too small, we should optimise this so that
we don't copy it twice.  This can be done by ensuring that it is
at least as large as the place where we'll write the checksum.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>


Cheers,

Comments

David Miller June 8, 2009, 7:22 a.m.
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Thu, 4 Jun 2009 21:06:00 +1000

> Hi:
> 
> tun: Optimise handling of bogus gso->hdr_len
> 
> As all current versions of virtio_net generate a value for the
> header length that's too small, we should optimise this so that
> we don't copy it twice.  This can be done by ensuring that it is
> at least as large as the place where we'll write the checksum.
> 
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Applied.
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Patch hide | download patch | download mbox

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 735bf41..00d00ad 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -563,6 +563,10 @@  static __inline__ ssize_t tun_get_user(struct tun_struct *tun,
 		if (memcpy_fromiovec((void *)&gso, iv, sizeof(gso)))
 			return -EFAULT;
 
+		if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
+		    gso.csum_start + gso.csum_offset + 2 > gso.hdr_len)
+			gso.hdr_len = gso.csum_start + gso.csum_offset + 2;
+
 		if (gso.hdr_len > len)
 			return -EINVAL;
 	}