Re: [PATCH] rtnetlink: Fix problem with buffer allocation

Le mardi 21 février 2012 à 12:47 -0800, Greg Rose a écrit :

Modifies the rtnl_calcit function to traverse the list of net
devices and compute the minimum buffer size that can hold the
info dumps of all matching devices based upon the filter passed
in via the new netlink attribute filter mask.  If no filter
mask is sent then the buffer allocation defaults to NLMSG_GOODSIZE.

...

+	/*
+	 * traverse the list of net devices and compute the minimum
+	 * buffer size based upon the filter mask.
+	 */
+	list_for_each_entry_rcu(dev, &net->dev_base_head, dev_list) {
+		min_ifinfo_dump_size = max_t(u16, min_ifinfo_dump_size,
+					     if_nlmsg_size(dev,
+						           ext_filter_mask));
+	}

Thats going to hurt some setups (thousand of devices on a server).

Also why are you using _rcu() variant here, we hold rtnl I presume ?