CLONE_PARENT shouldn't allow to set ->exit_signal

[firefly-linux-kernel-4.4.55.git] / kernel / watchdog.c

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index d117262deba305400ba768b1f7cecc945f3faba8..14bc092fb12c8bcd64ec1d848e42f9b1be50476d 100644 (file)
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -3,12 +3,9 @@
  *
  * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
  *
- * this code detects hard lockups: incidents in where on a CPU
- * the kernel does not respond to anything except NMI.
- *
- * Note: Most of this code is borrowed heavily from softlockup.c,
- * so thanks to Ingo for the initial implementation.
- * Some chunks also taken from arch/x86/kernel/apic/nmi.c, thanks
+ * Note: Most of this code is borrowed heavily from the original softlockup
+ * detector, so thanks to Ingo for the initial implementation.
+ * Some chunks also taken from the old x86-specific nmi watchdog code, thanks
  * to those contributors as well.
  */
 
@@ -117,9 +114,10 @@ static unsigned long get_sample_period(void)
 {
        /*
         * convert watchdog_thresh from seconds to ns
-        * the divide by 5 is to give hrtimer 5 chances to
-        * increment before the hardlockup detector generates
-        * a warning
+        * the divide by 5 is to give hrtimer several chances (two
+        * or three with the current relation between the soft
+        * and hard thresholds) to increment before the
+        * hardlockup detector generates a warning
         */
        return get_softlockup_thresh() * (NSEC_PER_SEC / 5);
 }
@@ -336,9 +334,11 @@ static int watchdog(void *unused)
 
        set_current_state(TASK_INTERRUPTIBLE);
        /*
-        * Run briefly once per second to reset the softlockup timestamp.
-        * If this gets delayed for more than 60 seconds then the
-        * debug-printout triggers in watchdog_timer_fn().
+        * Run briefly (kicked by the hrtimer callback function) once every
+        * get_sample_period() seconds (4 seconds by default) to reset the
+        * softlockup timestamp. If this gets delayed for more than
+        * 2*watchdog_thresh seconds then the debug-printout triggers in
+        * watchdog_timer_fn().
         */
        while (!kthread_should_stop()) {
                __touch_watchdog();