svn commit: r225372 - head/sys/kern

[Attilio Rao]

Author: attilio
Date: Sun Sep  4 13:07:02 2011
New Revision: 225372
URL: http://svn.freebsd.org/changeset/base/225372

Log:
  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

Modified:
  head/sys/kern/subr_kdb.c

Modified: head/sys/kern/subr_kdb.c
==============================================================================
--- head/sys/kern/subr_kdb.c    Sun Sep  4 05:04:34 2011        (r225371)
+++ head/sys/kern/subr_kdb.c    Sun Sep  4 13:07:02 2011        (r225372)
@@ -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 trap
        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 trap
 
        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 trap
 #ifdef SMP
        restart_cpus(stopped_cpus);
 #endif
+#ifdef SW_WATCHDOG
+       wdog_kern_pat(wdoglvt);
+#endif
 
        intr_restore(intr);
 
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