Commit d1643d24 authored Apr 18, 2008 by Alexey Dobriyan Committed by David S. Miller Apr 18, 2008

[NET]: Fix and allocate less memory for ->priv'less netdevices



This patch effectively reverts commit d0498d9a
aka "[NET]: Do not allocate unneeded memory for dev->priv alignment."
It was found to be buggy because of final unconditional += NETDEV_ALIGN_CONST
removal.

For example, for sizeof(struct net_device) being 2048 bytes, "alloc_size"
was also 2048 bytes, but allocator with debugging options turned on started
giving out !32-byte aligned memory resulting in redzones overwrites.

Patch does small optimization in ->priv'less case: bumping size to next
32-byte boundary was always done to ensure ->priv will also be aligned.
But, no ->priv, no need to do that.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 3c051235

net/core/dev.c

+9 −6

Original line number	Diff line number	Diff line
		@@ -3996,12 +3996,15 @@ struct net_device alloc_netdev_mq(int sizeof_priv, const char name,

		BUG_ON(strlen(name) >= sizeof(dev->name));

		/* ensure 32-byte alignment of both the device and private area */
		alloc_size = (sizeof(*dev) + NETDEV_ALIGN_CONST +
		(sizeof(struct net_device_subqueue) * (queue_count - 1))) &
		~NETDEV_ALIGN_CONST;
		if (sizeof_priv)
		alloc_size += sizeof_priv + NETDEV_ALIGN_CONST;
		alloc_size = sizeof(struct net_device) +
		sizeof(struct net_device_subqueue) * (queue_count - 1);
		if (sizeof_priv) {
		/* ensure 32-byte alignment of private area */
		alloc_size = (alloc_size + NETDEV_ALIGN_CONST) & ~NETDEV_ALIGN_CONST;
		alloc_size += sizeof_priv;
		}
		/* ensure 32-byte alignment of whole construct */
		alloc_size += NETDEV_ALIGN_CONST;

		p = kzalloc(alloc_size, GFP_KERNEL);
		if (!p) {

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