Lock down netnatm and mark as MPSAFE:

- Introduce a subsystem mutex, natm_mtx, manipulated with accessor macros
  NATM_LOCK_INIT(), NATM_LOCK(), NATM_UNLOCK(), NATM_LOCK_ASSERT().  It
  protects the consistency of pcb-related data structures.  Finer grained
  locking is possible, but should be done in the context of specific
  measurements (as very little work is done in netnatm -- most is in the
  ATM device driver or socket layer, so there's probably not much
  contention).

- Remove GIANT_REQUIRED, mark as NETISR_MPSAFE, remove
  NET_NEEDS_GIANT("netnatm").

- Conditionally acquire Giant when entering network interfaces for
  ifp->if_ioctl() using IFF_LOCKGIANT(ifp)/IFF_UNLOCKGIANT(ifp) in order
  to coexist with non-MPSAFE atm ifnet drivers..

- De-spl.

MFC after:	2 weeks
Reviewed by:	harti, bms (various versions)

1 files changed, 7 insertions, 0 deletions

diff --git a/sys/netnatm/natm.h b/sys/netnatm/natm.h
index 07b9c1c..325a6b8 100644
--- a/sys/netnatm/natm.h
+++ b/sys/netnatm/natm.h
@@ -95,6 +95,7 @@ LIST_HEAD(npcblist, natmpcb);
 
 /* global data structures */
 
+extern struct mtx natm_mtx;		/* global netnatm lock */
 extern struct npcblist natm_pcbs;	/* global list of pcbs */
 #define	NATM_STAT
 #ifdef NATM_STAT
@@ -104,6 +105,12 @@ extern	u_int	natm_sookcnt;
 extern	u_int	natm_sookbytes;		/* account of ok */
 #endif
 
+/* locking macros */
+#define	NATM_LOCK_INIT()	mtx_init(&natm_mtx, "natm_mtx", NULL, MTX_DEF)
+#define	NATM_LOCK()		mtx_lock(&natm_mtx)
+#define	NATM_UNLOCK()		mtx_unlock(&natm_mtx)
+#define	NATM_LOCK_ASSERT()	mtx_assert(&natm_mtx, MA_OWNED)
+
 /* external functions */
 
 /* natm_pcb.c */