svn commit: r356919 - head/sys/x86/x86

[Konstantin Belousov]

Author: kib
Date: Mon Jan 20 17:23:03 2020
New Revision: 356919
URL: https://svnweb.freebsd.org/changeset/base/356919

Log:
  x86: Wait for curthread to be set up as an indicator that the boot stack
  is no longer used.
  
  pc_curthread is set by cpu_switch after it stopped using the old
  thread (or boot) stack.  This makes the smp_after_idle_runnable()
  function not dependent on the internals of the scheduler operations.
  
  Reviewed by:	markj
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week
  Differential revision:	https://reviews.freebsd.org/D23276

Modified:
  head/sys/x86/x86/mp_x86.c

Modified: head/sys/x86/x86/mp_x86.c
==============================================================================
--- head/sys/x86/x86/mp_x86.c	Mon Jan 20 16:59:39 2020	(r356918)
+++ head/sys/x86/x86/mp_x86.c	Mon Jan 20 17:23:03 2020	(r356919)
@@ -1092,13 +1092,12 @@ init_secondary_tail(void)
 static void
 smp_after_idle_runnable(void *arg __unused)
 {
-	struct thread *idle_td;
+	struct pcpu *pc;
 	int cpu;
 
 	for (cpu = 1; cpu < mp_ncpus; cpu++) {
-		idle_td = pcpu_find(cpu)->pc_idlethread;
-		while (atomic_load_int(&idle_td->td_lastcpu) == NOCPU &&
-		    atomic_load_int(&idle_td->td_oncpu) == NOCPU)
+		pc = pcpu_find(cpu);
+		while (atomic_load_ptr(&pc->pc_curthread) == (uintptr_t)NULL)
 			cpu_spinwait();
 		kmem_free((vm_offset_t)bootstacks[cpu], kstack_pages *
 		    PAGE_SIZE);