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Message-ID: <3890679.FyyHKXfXOb@vostro.rjw.lan>
Date: Wed, 26 Feb 2014 02:23:35 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Lan Tianyu <tianyu.lan@...el.com>
Cc: tj@...nel.org, jolsa@...hat.com, oleg@...hat.com, lenb@...nel.org,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI/Processor: Rework processor throttling with work_on_cpu()
On Friday, February 21, 2014 01:35:45 PM Lan Tianyu wrote:
> acpi_processor_set_throttling() uses set_cpus_allowed_ptr() to make
> sure struct acpi_processor->acpi_processor_set_throttling() callback
> run on associated cpu. But the function maybe called in a worker which
> has been bound to a cpu. The patch is to replace set_cpus_allowed_ptr()
> with work_on_cpu().
>
> Signed-off-by: Lan Tianyu <tianyu.lan@...el.com>
> ---
> drivers/acpi/processor_throttling.c | 70 +++++++++++++++++--------------------
> 1 file changed, 33 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
> index 28baa05..2db105a 100644
> --- a/drivers/acpi/processor_throttling.c
> +++ b/drivers/acpi/processor_throttling.c
> @@ -56,6 +56,12 @@ struct throttling_tstate {
> int target_state; /* target T-state */
> };
>
> +struct acpi_processor_throttling_arg {
> + struct acpi_processor *pr;
> + int target_state;
> + bool force;
> +};
> +
> #define THROTTLING_PRECHANGE (1)
> #define THROTTLING_POSTCHANGE (2)
>
> @@ -1060,16 +1066,25 @@ static int acpi_processor_set_throttling_ptc(struct acpi_processor *pr,
> return 0;
> }
>
> +static long acpi_processor_throttling_fn(void *data)
> +{
> + struct acpi_processor_throttling_arg *arg = data;
> + struct acpi_processor *pr = arg->pr;
> + struct acpi_processor_throttling *p_throttling = &pr->throttling;
> +
> + return p_throttling->acpi_processor_set_throttling(pr,
> + arg->target_state, arg->force);
What about doing
return pr->throttling.acpi_processor_set_throttling(...);
directly without using the extra p_throttling pointer?
> +}
> +
> int acpi_processor_set_throttling(struct acpi_processor *pr,
> int state, bool force)
> {
> - cpumask_var_t saved_mask;
> int ret = 0;
> unsigned int i;
> struct acpi_processor *match_pr;
> struct acpi_processor_throttling *p_throttling;
> + struct acpi_processor_throttling_arg arg;
> struct throttling_tstate t_state;
> - cpumask_var_t online_throttling_cpus;
>
> if (!pr)
> return -EINVAL;
> @@ -1080,14 +1095,6 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
> if ((state < 0) || (state > (pr->throttling.state_count - 1)))
> return -EINVAL;
>
> - if (!alloc_cpumask_var(&saved_mask, GFP_KERNEL))
> - return -ENOMEM;
> -
> - if (!alloc_cpumask_var(&online_throttling_cpus, GFP_KERNEL)) {
> - free_cpumask_var(saved_mask);
> - return -ENOMEM;
> - }
> -
> if (cpu_is_offline(pr->id)) {
> /*
> * the cpu pointed by pr->id is offline. Unnecessary to change
> @@ -1096,17 +1103,15 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
> return -ENODEV;
> }
>
> - cpumask_copy(saved_mask, ¤t->cpus_allowed);
> t_state.target_state = state;
> p_throttling = &(pr->throttling);
> - cpumask_and(online_throttling_cpus, cpu_online_mask,
> - p_throttling->shared_cpu_map);
> +
> /*
> * The throttling notifier will be called for every
> * affected cpu in order to get one proper T-state.
> * The notifier event is THROTTLING_PRECHANGE.
> */
> - for_each_cpu(i, online_throttling_cpus) {
> + for_each_cpu_and(i, cpu_online_mask, p_throttling->shared_cpu_map) {
> t_state.cpu = i;
> acpi_processor_throttling_notifier(THROTTLING_PRECHANGE,
> &t_state);
> @@ -1118,21 +1123,18 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
> * it can be called only for the cpu pointed by pr.
> */
> if (p_throttling->shared_type == DOMAIN_COORD_TYPE_SW_ANY) {
> - /* FIXME: use work_on_cpu() */
> - if (set_cpus_allowed_ptr(current, cpumask_of(pr->id))) {
> - /* Can't migrate to the pr->id CPU. Exit */
> - ret = -ENODEV;
> - goto exit;
> - }
> - ret = p_throttling->acpi_processor_set_throttling(pr,
> - t_state.target_state, force);
> + arg.pr = pr;
> + arg.target_state = state;
> + arg.force = force;
> + ret = work_on_cpu(pr->id, acpi_processor_throttling_fn, &arg);
> } else {
> /*
> * When the T-state coordination is SW_ALL or HW_ALL,
> * it is necessary to set T-state for every affected
> * cpus.
> */
> - for_each_cpu(i, online_throttling_cpus) {
> + for_each_cpu_and(i, cpu_online_mask,
> + p_throttling->shared_cpu_map) {
> match_pr = per_cpu(processors, i);
> /*
> * If the pointer is invalid, we will report the
> @@ -1153,13 +1155,12 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
> "on CPU %d\n", i));
> continue;
> }
> - t_state.cpu = i;
> - /* FIXME: use work_on_cpu() */
> - if (set_cpus_allowed_ptr(current, cpumask_of(i)))
> - continue;
> - ret = match_pr->throttling.
> - acpi_processor_set_throttling(
> - match_pr, t_state.target_state, force);
> +
> + arg.pr = match_pr;
> + arg.target_state = state;
> + arg.force = force;
> + ret = work_on_cpu(pr->id, acpi_processor_throttling_fn,
> + &arg);
> }
> }
> /*
> @@ -1168,17 +1169,12 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
> * affected cpu to update the T-states.
> * The notifier event is THROTTLING_POSTCHANGE
> */
> - for_each_cpu(i, online_throttling_cpus) {
> + for_each_cpu_and(i, cpu_online_mask, p_throttling->shared_cpu_map) {
> t_state.cpu = i;
> acpi_processor_throttling_notifier(THROTTLING_POSTCHANGE,
> &t_state);
> }
> - /* restore the previous state */
> - /* FIXME: use work_on_cpu() */
> - set_cpus_allowed_ptr(current, saved_mask);
> -exit:
> - free_cpumask_var(online_throttling_cpus);
> - free_cpumask_var(saved_mask);
> +
> return ret;
> }
>
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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