Somewhat re-factor the read/write locking mechanism associated with the packet

filtering mechanisms to use the new rwlock(9) locking API:

- Drop the variables stored in the phil_head structure which were specific to
  conditions and the home rolled read/write locking mechanism.
- Drop some includes which were used for condition variables
- Drop the inline functions, and convert them to macros. Also, move these
  macros into pfil.h
- Move pfil list locking macros intp phil.h as well
- Rename ph_busy_count to ph_nhooks. This variable will represent the number
  of IN/OUT hooks registered with the pfil head structure
- Define PFIL_HOOKED macro which evaluates to true if there are any
  hooks to be ran by pfil_run_hooks
- In the IP/IP6 stacks, change the ph_busy_count comparison to use the new
  PFIL_HOOKED macro.
- Drop optimization in pfil_run_hooks which checks to see if there are any
  hooks to be ran, and returns if not. This check is already performed by the
  IP stacks when they call:

        if (!PFIL_HOOKED(ph))
                goto skip_hooks;

- Drop in assertion which makes sure that the number of hooks never drops
  below 0 for good measure. This in theory should never happen, and if it
  does than there are problems somewhere
- Drop special logic around PFIL_WAITOK because rw_wlock(9) does not sleep
- Drop variables which support home rolled read/write locking mechanism from
  the IPFW firewall chain structure.
- Swap out the read/write firewall chain lock internal to use the rwlock(9)
  API instead of our home rolled version
- Convert the inlined functions to macros

Reviewed by:	mlaier, andre, glebius
Thanks to:	jhb for the new locking API

1 files changed, 10 insertions, 45 deletions

diff --git a/sys/netinet/ip_fw2.c b/sys/netinet/ip_fw2.c
index e286951..ea43ece 100644
--- a/sys/netinet/ip_fw2.c
+++ b/sys/netinet/ip_fw2.c
@@ -50,9 +50,11 @@
 #include <sys/malloc.h>
 #include <sys/mbuf.h>
 #include <sys/kernel.h>
+#include <sys/lock.h>
 #include <sys/jail.h>
 #include <sys/module.h>
 #include <sys/proc.h>
+#include <sys/rwlock.h>
 #include <sys/socket.h>
 #include <sys/socketvar.h>
 #include <sys/sysctl.h>
@@ -131,54 +133,20 @@ struct ip_fw_chain {
 	struct ip_fw	*rules;		/* list of rules */
 	struct ip_fw	*reap;		/* list of rules to reap */
 	struct radix_node_head *tables[IPFW_TABLES_MAX];
-	struct mtx	mtx;		/* lock guarding rule list */
-	int		busy_count;	/* busy count for rw locks */
-	int		want_write;
-	struct cv	cv;
+	struct rwlock	rwmtx;
 };
 #define	IPFW_LOCK_INIT(_chain) \
-	mtx_init(&(_chain)->mtx, "IPFW static rules", NULL, \
-		MTX_DEF | MTX_RECURSE)
-#define	IPFW_LOCK_DESTROY(_chain)	mtx_destroy(&(_chain)->mtx)
+	rw_init(&(_chain)->rwmtx, "IPFW static rules")
+#define	IPFW_LOCK_DESTROY(_chain)	rw_destroy(&(_chain)->rwmtx)
 #define	IPFW_WLOCK_ASSERT(_chain)	do {				\
-	mtx_assert(&(_chain)->mtx, MA_OWNED);				\
+	rw_assert(rw, RA_WLOCKED);					\
 	NET_ASSERT_GIANT();						\
 } while (0)
 
-static __inline void
-IPFW_RLOCK(struct ip_fw_chain *chain)
-{
-	mtx_lock(&chain->mtx);
-	chain->busy_count++;
-	mtx_unlock(&chain->mtx);
-}
-
-static __inline void
-IPFW_RUNLOCK(struct ip_fw_chain *chain)
-{
-	mtx_lock(&chain->mtx);
-	chain->busy_count--;
-	if (chain->busy_count == 0 && chain->want_write)
-		cv_signal(&chain->cv);
-	mtx_unlock(&chain->mtx);
-}
-
-static __inline void
-IPFW_WLOCK(struct ip_fw_chain *chain)
-{
-	mtx_lock(&chain->mtx);
-	chain->want_write++;
-	while (chain->busy_count > 0)
-		cv_wait(&chain->cv, &chain->mtx);
-}
-
-static __inline void
-IPFW_WUNLOCK(struct ip_fw_chain *chain)
-{
-	chain->want_write--;
-	cv_signal(&chain->cv);
-	mtx_unlock(&chain->mtx);
-}
+#define IPFW_RLOCK(p) rw_rlock(&(p)->rwmtx)
+#define IPFW_RUNLOCK(p) rw_runlock(&(p)->rwmtx)
+#define IPFW_WLOCK(p) rw_wlock(&(p)->rwmtx)
+#define IPFW_WUNLOCK(p) rw_wunlock(&(p)->rwmtx)
 
 /*
  * list of rules for layer 3
@@ -4155,9 +4123,6 @@ ipfw_init(void)
 #endif
 
 	layer3_chain.rules = NULL;
-	layer3_chain.want_write = 0;
-	layer3_chain.busy_count = 0;
-	cv_init(&layer3_chain.cv, "Condition variable for IPFW rw locks");
 	IPFW_LOCK_INIT(&layer3_chain);
 	ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule zone",
 	    sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,