svn commit: r335183 - head/sys/kern

[Bryan Drewery]

Author: bdrewery
Date: Fri Jun 15 00:36:41 2018
New Revision: 335183
URL: https://svnweb.freebsd.org/changeset/base/335183

Log:
  proc0_post: Fix some locking issues
  
  - Filter out PRS_NEW procs as rufetch() tries taking the thread lock
    which may not yet be initialized.
  - Hold PROC_LOCK to ensure stability of iterating the threads.
  - p_rux fields are protected by the process statlock as well.
  
  MFC after:	2 weeks
  Reviewed by:	kib
  Sponsored by:	Dell EMC
  Differential Revision:	https://reviews.freebsd.org/D15809

Modified:
  head/sys/kern/init_main.c

Modified: head/sys/kern/init_main.c
==============================================================================
--- head/sys/kern/init_main.c	Thu Jun 14 23:10:10 2018	(r335182)
+++ head/sys/kern/init_main.c	Fri Jun 15 00:36:41 2018	(r335183)
@@ -618,17 +618,23 @@ proc0_post(void *dummy __unused)
 	 */
 	sx_slock(&allproc_lock);
 	FOREACH_PROC_IN_SYSTEM(p) {
+		PROC_LOCK(p);
+		if (p->p_state == PRS_NEW) {
+			PROC_UNLOCK(p);
+			continue;
+		}
 		microuptime(&p->p_stats->p_start);
 		PROC_STATLOCK(p);
 		rufetch(p, &ru);	/* Clears thread stats */
-		PROC_STATUNLOCK(p);
 		p->p_rux.rux_runtime = 0;
 		p->p_rux.rux_uticks = 0;
 		p->p_rux.rux_sticks = 0;
 		p->p_rux.rux_iticks = 0;
+		PROC_STATUNLOCK(p);
 		FOREACH_THREAD_IN_PROC(p, td) {
 			td->td_runtime = 0;
 		}
+		PROC_UNLOCK(p);
 	}
 	sx_sunlock(&allproc_lock);
 	PCPU_SET(switchtime, cpu_ticks());