From: Alexey Dobriyan Date: Fri, 18 Apr 2008 22:43:32 +0000 (-0700) Subject: [NET]: Fix and allocate less memory for ->priv'less netdevices X-Git-Tag: v2.6.26-rc1~1138^2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d1643d24c61b725bef399cc1cf2944b4c9c23177;p=linux-2.6 [NET]: Fix and allocate less memory for ->priv'less netdevices This patch effectively reverts commit d0498d9ae1a5cebac363e38907266d5cd2eedf89 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 Signed-off-by: David S. Miller --- diff --git a/net/core/dev.c b/net/core/dev.c index c16a07fde3..e1df1ab3e0 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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) {