Interrupts are disabled/enabled when entering and exiting the KDB context.

While this is generally good, it brings along a serie of problems,
like clocks going off sync and in presence of SW_WATCHDOG, watchdogs
firing without a good reason (missed hardclock wdog ticks update).

Fix the latter by kicking the watchdog just before to re-enable the interrupts.
Also, while here, not rely on users to stop the watchdog manually when
entering DDB but do that when entering KDB context.

Sponsored by: Sandvine Incorporated
Reviewed by:	emaste, rstone
Approved by:	re (kib)
MFC after:	1 week

1 files changed, 14 insertions, 0 deletions

diff --git a/sys/kern/subr_kdb.c b/sys/kern/subr_kdb.c
index 76b37a9..2ee7dc6 100644
--- a/sys/kern/subr_kdb.c
+++ b/sys/kern/subr_kdb.c
@@ -29,6 +29,7 @@ __FBSDID("$FreeBSD$");
 
 #include "opt_kdb.h"
 #include "opt_stack.h"
+#include "opt_watchdog.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -41,6 +42,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/smp.h>
 #include <sys/stack.h>
 #include <sys/sysctl.h>
+#ifdef SW_WATCHDOG
+#include <sys/watchdog.h>
+#endif
 
 #include <machine/kdb.h>
 #include <machine/pcb.h>
@@ -587,6 +591,9 @@ kdb_trap(int type, int code, struct trapframe *tf)
 	cpuset_t other_cpus;
 #endif
 	struct kdb_dbbe *be;
+#ifdef SW_WATCHDOG
+	u_int wdoglvt;
+#endif
 	register_t intr;
 	int handled;
 
@@ -600,6 +607,10 @@ kdb_trap(int type, int code, struct trapframe *tf)
 
 	intr = intr_disable();
 
+#ifdef SW_WATCHDOG
+	wdoglvt = wdog_kern_last_timeout();
+	wdog_kern_pat(WD_TO_NEVER);
+#endif
 #ifdef SMP
 	other_cpus = all_cpus;
 	CPU_CLR(PCPU_GET(cpuid), &other_cpus);
@@ -631,6 +642,9 @@ kdb_trap(int type, int code, struct trapframe *tf)
 #ifdef SMP
 	restart_cpus(stopped_cpus);
 #endif
+#ifdef SW_WATCHDOG
+	wdog_kern_pat(wdoglvt);
+#endif
 
 	intr_restore(intr);