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Hotplug CPU: don't check cpu_online after take_cpu_down

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Akinobu points out that if take_cpu_down() succeeds, the cpu must be offline.
Remove the cpu_online() check, and put a BUG_ON().

Quoting Akinobu Mita:
   Actually the cpu_online() check was necessary before appling this
   stop_machine: simplify patch.

   With old __stop_machine_run(), __stop_machine_run() could succeed
   (return !IS_ERR(p) value) even if take_cpu_down() returned non-zero value.
   The return value of take_cpu_down() was obtained through kthread_stop()..

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Akinobu Mita" <akinobu.mita@gmail.com>
This commit is contained in:
Rusty Russell
2008-07-28 12:16:29 -05:00
parent ffdb5976c4
commit 0432158758
1 changed files with 2 additions and 2 deletions
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4
kernel/cpu.c
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@@ -250,8 +250,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
set_cpus_allowed_ptr(current, &tmp); set_cpus_allowed_ptr(current, &tmp);
err = __stop_machine_run(take_cpu_down, &tcd_param, cpu); err = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
if (err) {
if (err || cpu_online(cpu)) {
/* CPU didn't die: tell everyone. Can't complain. */ /* CPU didn't die: tell everyone. Can't complain. */
if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod, if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
hcpu) == NOTIFY_BAD) hcpu) == NOTIFY_BAD)
@@ -259,6 +258,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
goto out_allowed; goto out_allowed;
} }
BUG_ON(cpu_online(cpu));
/* Wait for it to sleep (leaving idle task). */ /* Wait for it to sleep (leaving idle task). */
while (!idle_cpu(cpu)) while (!idle_cpu(cpu))