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

This patch effectively reverts commit d0498d9ae1
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>
This commit is contained in:
Alexey Dobriyan 2008-04-18 15:43:32 -07:00 committed by David S. Miller
parent 3c051235a7
commit d1643d24c6
1 changed files with 9 additions and 6 deletions
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15
net/core/dev.c
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@ -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) {