NET_LOCK() should raise IPL before acquiring the lock, and NET_UNLOCK()
should restore the level after releasing the lock. Otherwise, lock
recursion can occur, most likely right after the splx(). An example:
nd6_slowtimo <- NET_LOCK()
timeout_run
softclock
softintr_dispatch
dosoftint
interrupt
k_intr
if_netisr <- NET_LOCK()
taskq_thread
OK?
Index: sys/systm.h
===================================================================
RCS file: src/sys/sys/systm.h,v
retrieving revision 1.120
diff -u -p -r1.120 systm.h
--- sys/systm.h 19 Dec 2016 08:36:50 -0000 1.120
+++ sys/systm.h 23 Dec 2016 05:59:26 -0000
@@ -297,14 +297,14 @@ extern struct rwlock netlock;
#define NET_LOCK(s)
\
do { \
- rw_enter_write(&netlock); \
s = splsoftnet(); \
+ rw_enter_write(&netlock); \
} while (0)
-#define NET_UNLOCK(s) \
+#define NET_UNLOCK(s)
\
do { \
- splx(s); \
rw_exit_write(&netlock); \
+ splx(s); \
} while (0)
#define NET_ASSERT_LOCKED()
\
