kernel: watchdog: modify the explanation related to watchdog thread

The watchdog thread has been replaced by cpu_stop_work, modify the
explanation related.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Wang Qing <[e-mail]>
Reviewed-by: Petr Mladek <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Mauro Carvalho Chehab <[e-mail]>
Cc: Joe Perches <[e-mail]>
Cc: Stephen Kitt <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Randy Dunlap <[e-mail]>
Cc: "Guilherme G. Piccoli" <[e-mail]>
Cc: Qais Yousef <[e-mail]>
Cc: Santosh Sivaraj <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/watchdog.c

···
  * own hardlockup detector.
  *
  * watchdog_nmi_enable/disable can be implemented to start and stop when
- * softlockup watchdog threads start and stop. The arch must select the
+ * softlockup watchdog start and stop. The arch must select the
  * SOFTLOCKUP_DETECTOR Kconfig.
  */
 int __weak watchdog_nmi_enable(unsigned int cpu)
···
 static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work);
 
 /*
- * The watchdog thread function - touches the timestamp.
+ * The watchdog feed function - touches the timestamp.
  *
  * It only runs once every sample_period seconds (4 seconds by
  * default) to reset the softlockup timestamp. If this gets delayed
···
 }
 
 /*
- * Create the watchdog thread infrastructure and configure the detector(s).
- *
- * The threads are not unparked as watchdog_allowed_mask is empty.  When
- * the threads are successfully initialized, take the proper locks and
- * unpark the threads in the watchdog_cpumask if the watchdog is enabled.
+ * Create the watchdog infrastructure and configure the detector(s).
  */
 static __init void lockup_detector_setup(void)
 {
···
 
 #ifdef CONFIG_SYSCTL
 
-/* Propagate any changes to the watchdog threads */
+/* Propagate any changes to the watchdog infrastructure */
 static void proc_watchdog_update(void)
 {
 	/* Remove impossible cpus to keep sysctl output clean. */