Re: Dumb question: BKL on reboot ?

[Andrea Arcangeli]

On Thu, Aug 21, 2003 at 06:39:38PM +0200, Andrea Arcangeli wrote:
> static void do_machine_restart(void * __unused)
> {
> 	clear_bit(smp_processor_id(), &cpu_restart_map);
> 	if (smp_processor_id() == 0) {
> 	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> if the `reboot` program doesn't run by luck on cpu 0, it will be the one
> that will hang instead of the others. the above check must be changed to:
> 
> 	smp_processor_id() == reboot_cpu
> 
> and you should snapshot reboot_cpu in machine_restart_smp. then it won't
> hang anymore.

this untested patch should do the trick:

--- 2.4.22pre7aa1/arch/s390x/kernel/smp.c.~1~	2003-07-19 02:34:04.000000000 +0200
+++ 2.4.22pre7aa1/arch/s390x/kernel/smp.c	2003-08-21 18:48:05.000000000 +0200
@@ -240,11 +240,12 @@ void smp_send_stop(void)
  * Reboot, halt and power_off routines for SMP.
  */
 static volatile unsigned long cpu_restart_map;
+static unsigned long restart_cpu;
 
 static void do_machine_restart(void * __unused)
 {
 	clear_bit(smp_processor_id(), &cpu_restart_map);
-	if (smp_processor_id() == 0) {
+	if (smp_processor_id() == restart_cpu) {
 		/* Wait for all other cpus to enter do_machine_restart. */
 		while (cpu_restart_map != 0);
 		/* Store status of other cpus. */
@@ -263,6 +264,7 @@ static void do_machine_restart(void * __
 
 void machine_restart_smp(char * __unused) 
 {
+	restart_cpu = smp_processor_id();
 	cpu_restart_map = cpu_online_map;
         smp_call_function(do_machine_restart, NULL, 0, 0);
 	do_machine_restart(NULL);

Andrea
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