From: Rusty Russell Date: Mon, 28 Jul 2008 17:16:29 +0000 (-0500) Subject: Hotplug CPU: don't check cpu_online after take_cpu_down X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=04321587584272f4e8b9818f319f40caf8eeee13;p=linux-beck.git Hotplug CPU: don't check cpu_online after take_cpu_down 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 Cc: "Akinobu Mita" --- diff --git a/kernel/cpu.c b/kernel/cpu.c index cf79bb911371..53cf508f975a 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -250,8 +250,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) set_cpus_allowed_ptr(current, &tmp); err = __stop_machine_run(take_cpu_down, &tcd_param, cpu); - - if (err || cpu_online(cpu)) { + if (err) { /* CPU didn't die: tell everyone. Can't complain. */ if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod, hcpu) == NOTIFY_BAD) @@ -259,6 +258,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) goto out_allowed; } + BUG_ON(cpu_online(cpu)); /* Wait for it to sleep (leaving idle task). */ while (!idle_cpu(cpu))