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Date:      Fri, 27 Mar 2015 13:26:59 +0000 (UTC)
From:      Fabien Thomas <fabient@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r280759 - head/sys/netinet
Message-ID:  <201503271326.t2RDQxd3056112@svn.freebsd.org>
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Author: fabient
Date: Fri Mar 27 13:26:59 2015
New Revision: 280759
URL: https://svnweb.freebsd.org/changeset/base/280759

Log:
  On multi CPU systems, we may emit successive packets with the same id.
  Fix the race by using an atomic operation.
  
  Differential Revision:	https://reviews.freebsd.org/D2141
  Obtained from:	emeric.poupon@stormshield.eu
  MFC after:	1 week
  Sponsored by:	Stormshield

Modified:
  head/sys/netinet/ip_output.c
  head/sys/netinet/ip_var.h

Modified: head/sys/netinet/ip_output.c
==============================================================================
--- head/sys/netinet/ip_output.c	Fri Mar 27 12:45:20 2015	(r280758)
+++ head/sys/netinet/ip_output.c	Fri Mar 27 13:26:59 2015	(r280759)
@@ -91,7 +91,7 @@ __FBSDID("$FreeBSD$");
 
 #include <security/mac/mac_framework.h>
 
-VNET_DEFINE(u_short, ip_id);
+VNET_DEFINE(uint32_t, ip_id);
 
 #ifdef MBUF_STRESS_TEST
 static int mbuf_frag_size = 0;

Modified: head/sys/netinet/ip_var.h
==============================================================================
--- head/sys/netinet/ip_var.h	Fri Mar 27 12:45:20 2015	(r280758)
+++ head/sys/netinet/ip_var.h	Fri Mar 27 13:26:59 2015	(r280759)
@@ -174,7 +174,7 @@ struct inpcb;
 struct route;
 struct sockopt;
 
-VNET_DECLARE(u_short, ip_id);			/* ip packet ctr, for ids */
+VNET_DECLARE(uint32_t, ip_id);			/* ip packet ctr, for ids */
 VNET_DECLARE(int, ip_defttl);			/* default IP ttl */
 VNET_DECLARE(int, ipforwarding);		/* ip forwarding */
 #ifdef IPSTEALTH
@@ -228,7 +228,7 @@ struct in_ifaddr *
 void	ip_savecontrol(struct inpcb *, struct mbuf **, struct ip *,
 	    struct mbuf *);
 void	ip_slowtimo(void);
-u_int16_t	ip_randomid(void);
+uint16_t	ip_randomid(void);
 int	rip_ctloutput(struct socket *, struct sockopt *);
 void	rip_ctlinput(int, struct sockaddr *, void *);
 void	rip_init(void);
@@ -305,8 +305,18 @@ extern int	(*ip_dn_io_ptr)(struct mbuf *
 
 VNET_DECLARE(int, ip_do_randomid);
 #define	V_ip_do_randomid	VNET(ip_do_randomid)
-#define	ip_newid()	((V_ip_do_randomid != 0) ? ip_randomid() : \
-			    htons(V_ip_id++))
+static __inline uint16_t
+ip_newid(void)
+{
+	uint16_t res;
+
+	if (V_ip_do_randomid != 0)
+		return (ip_randomid());
+	else {
+		res = atomic_fetchadd_32(&V_ip_id, 1) & 0xFFFF;
+		return (htons(res));
+	}
+}
 
 #endif /* _KERNEL */

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