svn commit: r331375 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Thu Mar 22 20:47:25 2018
New Revision: 331375
URL: https://svnweb.freebsd.org/changeset/base/331375

Log:
  Do not send signals to init directly from shutdown_nice(9), do it from
  the task context.
  
  shutdown_nice() is used from the fast interrupt handlers, mostly for
  console drivers, where we cannot lock blockable locks.  Schedule the
  task in the fast queue to send the signal from the proper context.
  
  Reviewed by:	imp
  Discussed with:	bde
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/kern/kern_shutdown.c

Modified: head/sys/kern/kern_shutdown.c
==============================================================================
--- head/sys/kern/kern_shutdown.c	Thu Mar 22 20:44:27 2018	(r331374)
+++ head/sys/kern/kern_shutdown.c	Thu Mar 22 20:47:25 2018	(r331375)
@@ -72,6 +72,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/smp.h>
 #include <sys/sysctl.h>
 #include <sys/sysproto.h>
+#include <sys/taskqueue.h>
 #include <sys/vnode.h>
 #include <sys/watchdog.h>
 
@@ -276,6 +277,28 @@ sys_reboot(struct thread *td, struct reboot_args *uap)
 	return (error);
 }
 
+static void
+shutdown_nice_task_fn(void *arg, int pending __unused)
+{
+	int howto;
+
+	howto = (uintptr_t)arg;
+	/* Send a signal to init(8) and have it shutdown the world. */
+	PROC_LOCK(initproc);
+	if (howto & RB_POWEROFF)
+		kern_psignal(initproc, SIGUSR2);
+	else if (howto & RB_POWERCYCLE)
+		kern_psignal(initproc, SIGWINCH);
+	else if (howto & RB_HALT)
+		kern_psignal(initproc, SIGUSR1);
+	else
+		kern_psignal(initproc, SIGINT);
+	PROC_UNLOCK(initproc);
+}
+
+static struct task shutdown_nice_task = TASK_INITIALIZER(0,
+    &shutdown_nice_task_fn, NULL);
+
 /*
  * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
  */
@@ -283,20 +306,14 @@ void
 shutdown_nice(int howto)
 {
 
-	if (initproc != NULL) {
-		/* Send a signal to init(8) and have it shutdown the world. */
-		PROC_LOCK(initproc);
-		if (howto & RB_POWEROFF)
-			kern_psignal(initproc, SIGUSR2);
-		else if (howto & RB_POWERCYCLE)
-			kern_psignal(initproc, SIGWINCH);
-		else if (howto & RB_HALT)
-			kern_psignal(initproc, SIGUSR1);
-		else
-			kern_psignal(initproc, SIGINT);
-		PROC_UNLOCK(initproc);
+	if (initproc != NULL && !SCHEDULER_STOPPED()) {
+		shutdown_nice_task.ta_context = (void *)(uintptr_t)howto;
+		taskqueue_enqueue(taskqueue_fast, &shutdown_nice_task);
 	} else {
-		/* No init(8) running, so simply reboot. */
+		/*
+		 * No init(8) running, or scheduler would not allow it
+		 * to run, so simply reboot.
+		 */
 		kern_reboot(howto | RB_NOSYNC);
 	}
 }