Re: [PATCH net-next] net: move inet_dport/inet_num in sock_common

[Eric Dumazet <eric.dumazet@gmail.com>]

On Tue, 2012-11-27 at 13:23 -0800, Eric Dumazet wrote:
> On Tue, 2012-11-27 at 19:05 +0000, Ben Hutchings wrote:
> > On Tue, 2012-11-27 at 07:06 -0800, Eric Dumazet wrote:
> 
> > >  struct sock_common {
> > > -	/* skc_daddr and skc_rcv_saddr must be grouped :
> > > -	 * cf INET_MATCH() and INET_TW_MATCH()
> > > +	/* skc_daddr and skc_rcv_saddr must be grouped on a 8 bytes aligned
> > > +	 * address on 64bit arches : cf INET_MATCH() and INET_TW_MATCH()
> > 
> > __aligned(8)?
> 
> Nope, only on 64 bit this requirement exists (since a long time)
> 
> I am not sure we want complexity on this.
> 
> And we dont want holes to be automatically added here neither.

Hmm, maybe the following could be the right way, as we did
for skc_hash/skc_u16hashes


 struct sock_common {
-       /* skc_daddr and skc_rcv_saddr must be grouped :
-        * cf INET_MATCH() and INET_TW_MATCH()
+       /* skc_daddr and skc_rcv_saddr must be grouped on a 8 bytes aligned
+        * address on 64bit arches : cf INET_MATCH() and INET_TW_MATCH()
         */
-       __be32                  skc_daddr;
-       __be32                  skc_rcv_saddr;
-
+       union {
+               unsigned long   skc_laddr;
+               struct {
+                       __be32  skc_daddr;
+                       __be32  skc_rcv_saddr;
+               };
+       };
        union  {
                unsigned int    skc_hash;
                __u16           skc_u16hashes[2];
        };
+       /* skc_dport && skc_num must be grouped as well */
+       union {
+               unsigned int    skc_ports;
+               struct {
+                       __be16  skc_dport;
+                       __u16   skc_num;
+               };
+       };
+
        unsigned short          skc_family;
        volatile unsigned char  skc_state;
        unsigned char           skc_reuse;