On Tue, Apr 14, 2015 at 10:33:18AM -0500, Thomas Falcon wrote: > On 04/13/2015 12:39 AM, David Gibson wrote: > > AFAIK the PAPR document which defines the virtual device interface used by > > the ibmveth driver doesn't specify a specific maximum MTU. So, in the > > ibmveth driver, the maximum allowed MTU is determined by the maximum > > allocated buffer size of 64k (corresponding to one page in the common case) > > minus the per-buffer overhead IBMVETH_BUFF_OH (which has value 22 for 14 > > bytes of ethernet header, plus 8 bytes for an opaque handle). > > > > This suggests a maximum allowable MTU of 65514 bytes, but in fact the > > driver only permits a maximum MTU of 65513. This is because there is a < > > instead of an <= in ibmveth_change_mtu(), which only permits an MTU which > > is strictly smaller than the buffer size, rather than allowing the buffer > > to be completely filled. > > > > This patch fixes the buglet. > > > The same expression is made using < just a few lines above. Shouldn't this > be changed to <= too? > > @@ -1238,7 +1238,7 @@ static int ibmveth_change_mtu(struct net_device *dev, > int new_mtu) > return -EINVAL; > > for (i = 0; i < IBMVETH_NUM_BUFF_POOLS; i++) > - if (new_mtu_oh < adapter->rx_buff_pool[i].buff_size) > + if (new_mtu_oh <= adapter->rx_buff_pool[i].buff_size) > break; > > if (i == IBMVETH_NUM_BUFF_POOLS)
Yes, yes it should.
Good catch, thanks.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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