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79 lines
2.8 KiB
Diff
79 lines
2.8 KiB
Diff
From 95b8bbff6ecf0692747622af16d917a67313f8cc Mon Sep 17 00:00:00 2001
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From: Jarod Wilson <jarod@redhat.com>
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Date: Fri, 7 Oct 2016 22:04:33 -0400
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Subject: [PATCH] net: centralize net_device min/max MTU checking
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While looking into an MTU issue with sfc, I started noticing that almost
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every NIC driver with an ndo_change_mtu function implemented almost
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exactly the same range checks, and in many cases, that was the only
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practical thing their ndo_change_mtu function was doing. Quite a few
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drivers have either 68, 64, 60 or 46 as their minimum MTU value checked,
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and then various sizes from 1500 to 65535 for their maximum MTU value. We
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can remove a whole lot of redundant code here if we simple store min_mtu
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and max_mtu in net_device, and check against those in net/core/dev.c's
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dev_set_mtu().
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In theory, there should be zero functional change with this patch, it just
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puts the infrastructure in place. Subsequent patches will attempt to start
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using said infrastructure, with theoretically zero change in
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functionality.
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CC: netdev@vger.kernel.org
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Signed-off-by: Jarod Wilson <jarod@redhat.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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include/linux/netdevice.h | 4 ++++
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net/core/dev.c | 13 +++++++++++--
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2 files changed, 15 insertions(+), 2 deletions(-)
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diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
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index 780e7171f548..2082b7d02a77 100644
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--- a/include/linux/netdevice.h
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+++ b/include/linux/netdevice.h
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@@ -1507,6 +1507,8 @@ enum netdev_priv_flags {
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* @if_port: Selectable AUI, TP, ...
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* @dma: DMA channel
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* @mtu: Interface MTU value
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+ * @min_mtu: Interface Minimum MTU value
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+ * @max_mtu: Interface Maximum MTU value
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* @type: Interface hardware type
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* @hard_header_len: Maximum hardware header length.
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* @min_header_len: Minimum hardware header length
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@@ -1728,6 +1730,8 @@ struct net_device {
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unsigned char dma;
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unsigned int mtu;
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+ unsigned int min_mtu;
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+ unsigned int max_mtu;
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unsigned short type;
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unsigned short hard_header_len;
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unsigned short min_header_len;
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diff --git a/net/core/dev.c b/net/core/dev.c
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index 2e04fd188081..c7ec56e8659a 100644
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--- a/net/core/dev.c
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+++ b/net/core/dev.c
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@@ -6524,9 +6524,18 @@ int dev_set_mtu(struct net_device *dev, int new_mtu)
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if (new_mtu == dev->mtu)
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return 0;
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- /* MTU must be positive. */
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- if (new_mtu < 0)
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+ /* MTU must be positive, and in range */
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+ if (new_mtu < 0 || new_mtu < dev->min_mtu) {
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+ net_err_ratelimited("%s: Invalid MTU %d requested, hw min %d\n",
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+ dev->name, new_mtu, dev->min_mtu);
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return -EINVAL;
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+ }
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+
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+ if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) {
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+ net_err_ratelimited("%s: Invalid MTU %d requested, hw max %d\n",
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+ dev->name, new_mtu, dev->min_mtu);
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+ return -EINVAL;
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+ }
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if (!netif_device_present(dev))
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return -ENODEV;
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--
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2.11.1
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