[NET]: Do not allocate unneeded memory for dev->priv alignment.
The alloc_netdev_mq() tries to produce 32-bytes alignment for both the net_device itself and its private data. The second alignment is achieved by adding the NETDEV_ALIGN_CONST to the whole size of the memory to be allocated. However, for those devices that do not need the private area, this addition just makes the net_device weight 1024 + 32 = 1068 bytes, i.e. consume twice as much memory. Since loopback device is such (sizeof_priv == 0 for it), and each net namespace creates one, this can save a noticeable amount of memory for kernel with net namespaces turned on. After this set the lo device is actually allocated from a size-1024 kmem cache on i386 box even with NETPOLL and WIRELESS_EXT turned on. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -4000,7 +4000,8 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
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alloc_size = (sizeof(*dev) + NETDEV_ALIGN_CONST +
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(sizeof(struct net_device_subqueue) * (queue_count - 1))) &
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~NETDEV_ALIGN_CONST;
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alloc_size += sizeof_priv + NETDEV_ALIGN_CONST;
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if (sizeof_priv)
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alloc_size += sizeof_priv + NETDEV_ALIGN_CONST;
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p = kzalloc(alloc_size, GFP_KERNEL);
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if (!p) {
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