From 1030a1a9cb2f9c6bf2c8cd3cdc77c06794abc86f Mon Sep 17 00:00:00 2001
From: Max Laier <mlaier@FreeBSD.org>
Date: Sun, 25 Nov 2007 12:41:47 +0000
Subject: [PATCH] pfil(9) locking take 3:  Switch to rmlock(9) This has the
 benefit that rmlocks have proper support for reader recursion (in contrast to
 rwlock(9) which could potential lead to writer stravation). It also means a
 significant performance gain, eventhough only visible in microbenchmarks at
 the moment.

Discussed on:	-arch, -net
---
 sys/net/pfil.c | 11 ++++++-----
 sys/net/pfil.h | 15 +++++++++------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/sys/net/pfil.c b/sys/net/pfil.c
index 78b87f3179c..bb82bb313ac 100644
--- a/sys/net/pfil.c
+++ b/sys/net/pfil.c
@@ -34,7 +34,7 @@
 #include <sys/errno.h>
 #include <sys/lock.h>
 #include <sys/malloc.h>
-#include <sys/rwlock.h>
+#include <sys/rmlock.h>
 #include <sys/socket.h>
 #include <sys/socketvar.h>
 #include <sys/systm.h>
@@ -66,11 +66,12 @@ int
 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
     int dir, struct inpcb *inp)
 {
+	struct rm_priotracker rmpt;
 	struct packet_filter_hook *pfh;
 	struct mbuf *m = *mp;
 	int rv = 0;
 
-	PFIL_RLOCK(ph);
+	PFIL_RLOCK(ph, &rmpt);
 	KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
 	for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
 	     pfh = TAILQ_NEXT(pfh, pfil_link)) {
@@ -80,7 +81,7 @@ pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
 				break;
 		}
 	}
-	PFIL_RUNLOCK(ph);
+	PFIL_RUNLOCK(ph, &rmpt);
 	
 	*mp = m;
 	return (rv);
@@ -104,7 +105,7 @@ pfil_head_register(struct pfil_head *ph)
 		}
 	PFIL_LIST_UNLOCK();
 
-	rw_init(&ph->ph_mtx, "PFil hook read/write mutex");
+	PFIL_LOCK_INIT(ph);
 	PFIL_WLOCK(ph);
 	ph->ph_nhooks = 0;
 
@@ -143,7 +144,7 @@ pfil_head_unregister(struct pfil_head *ph)
 		free(pfh, M_IFADDR);
 	TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
 		free(pfh, M_IFADDR);
-	rw_destroy(&ph->ph_mtx);
+	PFIL_LOCK_DESTROY(ph);
 	
 	return (0);
 }
diff --git a/sys/net/pfil.h b/sys/net/pfil.h
index d2308fdbee5..22d3d16010a 100644
--- a/sys/net/pfil.h
+++ b/sys/net/pfil.h
@@ -37,7 +37,7 @@
 #include <sys/_lock.h>
 #include <sys/_mutex.h>
 #include <sys/lock.h>
-#include <sys/rwlock.h>
+#include <sys/rmlock.h>
 
 struct mbuf;
 struct ifnet;
@@ -69,7 +69,7 @@ struct pfil_head {
 	pfil_list_t	ph_out;
 	int		ph_type;
 	int		ph_nhooks;
-	struct rwlock	ph_mtx;
+	struct rmlock	ph_lock;
 	union {
 		u_long		phu_val;
 		void		*phu_ptr;
@@ -93,10 +93,13 @@ int	pfil_head_unregister(struct pfil_head *);
 struct pfil_head *pfil_head_get(int, u_long);
 
 #define	PFIL_HOOKED(p) ((p)->ph_nhooks > 0)
-#define PFIL_RLOCK(p) rw_rlock(&(p)->ph_mtx)
-#define PFIL_WLOCK(p) rw_wlock(&(p)->ph_mtx)
-#define PFIL_RUNLOCK(p) rw_runlock(&(p)->ph_mtx)
-#define PFIL_WUNLOCK(p) rw_wunlock(&(p)->ph_mtx)
+#define	PFIL_LOCK_INIT(p) \
+    rm_init(&(p)->ph_lock, "PFil hook read/write mutex", LO_RECURSABLE)
+#define	PFIL_LOCK_DESTROY(p) rm_destroy(&(p)->ph_lock)
+#define PFIL_RLOCK(p, t) rm_rlock(&(p)->ph_lock, (t))
+#define PFIL_WLOCK(p) rm_wlock(&(p)->ph_lock)
+#define PFIL_RUNLOCK(p, t) rm_runlock(&(p)->ph_lock, (t))
+#define PFIL_WUNLOCK(p) rm_wunlock(&(p)->ph_lock)
 #define PFIL_LIST_LOCK() mtx_lock(&pfil_global_lock)
 #define PFIL_LIST_UNLOCK() mtx_unlock(&pfil_global_lock)