Re: POINTER_ALIGNED_P (was: Re: CVS commit: src/sys)

[christos%astron.com@localhost (Christos Zoulas)]

In article <YCxJ044lGyfLpKuP%pony.stderr.spb.ru@localhost>,
Valery Ushakov  <uwe%stderr.spb.ru@localhost> wrote:

>But to get back to my main point, PLEASE, can we stop making random
>aimless changes without prior discussion?

Here's the change I'd like to make:
- pass the alignment instead of the mask (as Roy asked and to match the
  other macro)
- use alignof to determine that alignment and CTASSERT what we expect
- remove unused macros

This incrementally improves things.

christos

Index: net/if_arp.h
===================================================================
RCS file: /cvsroot/src/sys/net/if_arp.h,v
retrieving revision 1.41
diff -u -p -u -r1.41 if_arp.h
--- net/if_arp.h	16 Feb 2021 10:20:56 -0000	1.41
+++ net/if_arp.h	17 Feb 2021 17:45:55 -0000
@@ -72,7 +72,8 @@ struct	arphdr {
 	uint8_t  ar_tpa[];	/* target protocol address */
 #endif
 };
-#define	ARP_HDR_ALIGNMENT	1
+#define	ARP_HDR_ALIGNMENT	__alignof(struct arphdr)
+__CTASSERT(ARP_HDR_ALIGNMENT == 2);
 
 static __inline uint8_t *
 ar_data(struct arphdr *ap)
Index: netinet/icmp_private.h
===================================================================
RCS file: /cvsroot/src/sys/netinet/icmp_private.h,v
retrieving revision 1.4
diff -u -p -u -r1.4 icmp_private.h
--- netinet/icmp_private.h	14 Feb 2021 20:58:35 -0000	1.4
+++ netinet/icmp_private.h	17 Feb 2021 17:45:55 -0000
@@ -44,7 +44,6 @@ extern percpu_t *icmpstat_percpu;
 
 #define	ICMP_STATINC(x)		_NET_STATINC(icmpstat_percpu, x)
 
-#define	ICMP_HDR_ALIGNMENT	3
 #endif /* _KERNEL_ */
 
 #endif /* !_NETINET_ICMP_PRIVATE_H_ */
Index: netinet/igmp_var.h
===================================================================
RCS file: /cvsroot/src/sys/netinet/igmp_var.h,v
retrieving revision 1.26
diff -u -p -u -r1.26 igmp_var.h
--- netinet/igmp_var.h	14 Feb 2021 20:58:35 -0000	1.26
+++ netinet/igmp_var.h	17 Feb 2021 17:45:55 -0000
@@ -105,8 +105,6 @@
  */
 #define	IGMP_RANDOM_DELAY(X)	(cprng_fast32() % (X) + 1)
 
-#define	IGMP_HDR_ALIGNMENT	3
-
 void	igmp_init(void);
 void	igmp_input(struct mbuf *, int, int);
 int	igmp_joingroup(struct in_multi *);
Index: netinet/ip_private.h
===================================================================
RCS file: /cvsroot/src/sys/netinet/ip_private.h,v
retrieving revision 1.4
diff -u -p -u -r1.4 ip_private.h
--- netinet/ip_private.h	14 Feb 2021 20:58:35 -0000	1.4
+++ netinet/ip_private.h	17 Feb 2021 17:45:55 -0000
@@ -43,7 +43,8 @@ extern	percpu_t *ipstat_percpu;
 #define	IP_STATINC(x)		_NET_STATINC(ipstat_percpu, x)
 #define	IP_STATDEC(x)		_NET_STATDEC(ipstat_percpu, x)
 
-#define	IP_HDR_ALIGNMENT	3
+#define	IP_HDR_ALIGNMENT	__alignof(struct ip)
+__CTASSERT(IP_HDR_ALIGNMENT == 4);
 #endif /* _KERNEL */
 
 #endif /* !_NETINET_IP_PRIVATE_H_ */
Index: netinet/tcp_private.h
===================================================================
RCS file: /cvsroot/src/sys/netinet/tcp_private.h,v
retrieving revision 1.4
diff -u -p -u -r1.4 tcp_private.h
--- netinet/tcp_private.h	14 Feb 2021 20:58:35 -0000	1.4
+++ netinet/tcp_private.h	17 Feb 2021 17:45:55 -0000
@@ -43,7 +43,8 @@ extern	percpu_t *tcpstat_percpu;
 #define	TCP_STATINC(x)		_NET_STATINC(tcpstat_percpu, x)
 #define	TCP_STATADD(x, v)	_NET_STATADD(tcpstat_percpu, x, v)
 
-#define	TCP_HDR_ALIGNMENT	3
+#define	TCP_HDR_ALIGNMENT	__alignof(struct tcphdr)
+__CTASSERT(TCP_HDR_ALIGNMENT == 4);
 #endif /* _KERNEL */
 
 #endif /* !_NETINET_TCP_PRIVATE_H_ */
Index: netinet/udp_private.h
===================================================================
RCS file: /cvsroot/src/sys/netinet/udp_private.h,v
retrieving revision 1.4
diff -u -p -u -r1.4 udp_private.h
--- netinet/udp_private.h	14 Feb 2021 20:58:35 -0000	1.4
+++ netinet/udp_private.h	17 Feb 2021 17:45:55 -0000
@@ -39,7 +39,8 @@ extern	percpu_t *udpstat_percpu;
 
 #define	UDP_STATINC(x)		_NET_STATINC(udpstat_percpu, x)
 
-#define	UDP_HDR_ALIGNMENT	3
+#define	UDP_HDR_ALIGNMENT	__alignof(struct udphdr)
+__CTASSERT(UDP_HDR_ALIGNMENT == 2);
 #endif /* _KERNEL */
 
 #endif /* !_NETINET_UDP_PRIVATE_H_ */
Index: netinet6/ip6_private.h
===================================================================
RCS file: /cvsroot/src/sys/netinet6/ip6_private.h,v
retrieving revision 1.4
diff -u -p -u -r1.4 ip6_private.h
--- netinet6/ip6_private.h	14 Feb 2021 20:58:35 -0000	1.4
+++ netinet6/ip6_private.h	17 Feb 2021 17:45:55 -0000
@@ -43,7 +43,8 @@ extern	percpu_t *ip6stat_percpu;
 #define	IP6_STATINC(x)		_NET_STATINC(ip6stat_percpu, x)
 #define	IP6_STATDEC(x)		_NET_STATDEC(ip6stat_percpu, x)
 
-#define	IP6_HDR_ALIGNMENT	3
+#define	IP6_HDR_ALIGNMENT	__alignof(struct ip6_hdr)
+__CTASSERT(IP6_HDR_ALIGNMENT == 4);
 #endif /* _KERNEL */
 
 #endif /* !_NETINET_IP6_PRIVATE_H_ */
Index: sys/mbuf.h
===================================================================
RCS file: /cvsroot/src/sys/sys/mbuf.h,v
retrieving revision 1.230
diff -u -p -u -r1.230 mbuf.h
--- sys/mbuf.h	15 Feb 2021 09:29:56 -0000	1.230
+++ sys/mbuf.h	17 Feb 2021 17:45:55 -0000
@@ -846,10 +846,11 @@ m_copy_rcvif(struct mbuf *m, const struc
 static __inline int
 m_get_aligned_hdr(struct mbuf **m, int align, size_t hlen, bool linkhdr)
 {
-	if (POINTER_ALIGNED_P(mtod(*m, void *), align) == 0)
+	if (POINTER_ALIGNED_P(mtod(*m, void *), align) == 0) {
+		--align;	// Turn into mask
 		*m = m_copyup(*m, hlen, 
 		      linkhdr ? (max_linkhdr + align) & ~align : 0);
-	else if (__predict_false((size_t)(*m)->m_len < hlen))
+	} else if (__predict_false((size_t)(*m)->m_len < hlen))
 		*m = m_pullup(*m, hlen);
 	return *m == NULL;
 }
Index: sys/param.h
===================================================================
RCS file: /cvsroot/src/sys/sys/param.h,v
retrieving revision 1.688
diff -u -p -u -r1.688 param.h
--- sys/param.h	15 Feb 2021 19:46:53 -0000	1.688
+++ sys/param.h	17 Feb 2021 17:45:55 -0000
@@ -290,7 +290,7 @@
 #ifdef __NO_STRICT_ALIGNMENT
 #define	POINTER_ALIGNED_P(p, a)		1
 #else
-#define	POINTER_ALIGNED_P(p, a)		(((uintptr_t)(p) & (a)) == 0)
+#define	POINTER_ALIGNED_P(p, a)		(((uintptr_t)(p) & ((a) - 1)) == 0)
 #endif
 
 /*