On Wed, Jun 4, 2014 at 6:03 AM, Daniel Lezcano
<daniel.lezc...@linaro.org> wrote:
> On 06/04/2014 02:29 AM, Andy Lutomirski wrote:
>>
>> This doesn't change functionality at all, but I've misread this code
>> so many times that I want to make it a bit more obvious.
>>
>> Signed-off-by: Andy Lutomirski <l...@amacapital.net>
>> ---
>> kernel/sched/idle.c | 12 +++++++++++-
>> 1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
>> index 25b9423..2ec9f47 100644
>> --- a/kernel/sched/idle.c
>> +++ b/kernel/sched/idle.c
>> @@ -67,6 +67,10 @@ void __weak arch_cpu_idle(void)
>> * cpuidle_idle_call - the main idle function
>> *
>> * NOTE: no locks or semaphores should be used here
>> + *
>> + * On archs that support TIF_POLLING_NRFLAG, is called with polling
>> + * set, and it returns with polling set. If it ever stops polling, it
>> + * must clear the polling bit.
>> */
>> static void cpuidle_idle_call(void)
>> {
>> @@ -178,7 +182,14 @@ exit_idle:
>> */
>> static void cpu_idle_loop(void)
>> {
>> + __current_set_polling();
>> +
>> while (1) {
>> + /*
>> + * Invariant: polling is set here (assuming that the arch
>> + * has a polling bit.
>> + */
>> +
>
>
> nit : extra line
>
It was intentional: the comment is about this point in the loop, not
about the tick_nohz_idle_enter call. I'm not attached to it, though.
>
>> tick_nohz_idle_enter();
>>
>> while (!need_resched()) {
>> @@ -239,7 +250,6 @@ void cpu_startup_entry(enum cpuhp_state state)
>> */
>> boot_init_stack_canary();
>> #endif
>> - __current_set_polling();
>
>
> I don't get the connection with the patch description.
>
In retrospect, I think I can just fold this patch with the one after
it. I wrote this because I could never remember who is responsible
for setting polling in the first place.
--Andy
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