svn commit: r332871 - head/sys/kern

[Tijl Coosemans]

Author: tijl
Date: Sun Apr 22 16:05:29 2018
New Revision: 332871
URL: https://svnweb.freebsd.org/changeset/base/332871

Log:
  Make bufdaemon and bufspacedaemon use kthread_suspend_check instead of
  kproc_suspend_check.  In r329612 bufspacedaemon was turned into a thread
  of the bufdaemon process causing both to call kproc_suspend_check with the
  same proc argument and that function contains the following while loop:
  
  while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
  	wakeup(&p->p_siglist);
  	msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
  }
  
  So one thread wakes up the other and the other wakes up the first again,
  locking up UP machines on shutdown.
  
  Also register the shutdown handlers with SHUTDOWN_PRI_LAST + 100 so they
  run after the syncer has shutdown, because the syncer can cause a
  situation where bufdaemon help is needed to proceed.
  
  PR:		227404
  Reviewed by:	kib
  Tested by:	cy, rmacklem

Modified:
  head/sys/kern/vfs_bio.c

Modified: head/sys/kern/vfs_bio.c
==============================================================================
--- head/sys/kern/vfs_bio.c	Sun Apr 22 09:30:07 2018	(r332870)
+++ head/sys/kern/vfs_bio.c	Sun Apr 22 16:05:29 2018	(r332871)
@@ -791,9 +791,12 @@ bufspace_daemon(void *arg)
 {
 	struct bufdomain *bd;
 
+	EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
+	    SHUTDOWN_PRI_LAST + 100);
+
 	bd = arg;
 	for (;;) {
-		kproc_suspend_check(curproc);
+		kthread_suspend_check();
 
 		/*
 		 * Free buffers from the clean queue until we meet our
@@ -3357,8 +3360,8 @@ buf_daemon()
 	/*
 	 * This process needs to be suspended prior to shutdown sync.
 	 */
-	EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
-	    SHUTDOWN_PRI_LAST);
+	EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
+	    SHUTDOWN_PRI_LAST + 100);
 
 	/*
 	 * Start the buf clean daemons as children threads.
@@ -3381,7 +3384,7 @@ buf_daemon()
 		bd_request = 0;
 		mtx_unlock(&bdlock);
 
-		kproc_suspend_check(bufdaemonproc);
+		kthread_suspend_check();
 
 		/*
 		 * Save speedupreq for this pass and reset to capture new