linux-kernel - RE: [PATCH 2/2] ACPI: processor: idle: Remove obsolete comment

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <SJ0PR11MB66228319834B1C7B48FCE52EF5AD2@SJ0PR11MB6622.namprd11.prod.outlook.com>
Date: Mon, 31 Mar 2025 07:38:35 +0000
From: "Zhang, Rui" <rui.zhang@...el.com>
To: Giovanni Gherdovich <ggherdovich@...e.cz>, "Rafael J . Wysocki"
	<rafael@...nel.org>
CC: Len Brown <lenb@...nel.org>, "linux-acpi@...r.kernel.org"
	<linux-acpi@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-pm@...r.kernel.org"
	<linux-pm@...r.kernel.org>
Subject: RE: [PATCH 2/2] ACPI: processor: idle: Remove obsolete comment

> -----Original Message-----
> From: Giovanni Gherdovich <ggherdovich@...e.cz>
> Sent: Friday, March 28, 2025 10:31 PM
> To: Rafael J . Wysocki <rafael@...nel.org>; Zhang, Rui <rui.zhang@...el.com>
> Cc: Len Brown <lenb@...nel.org>; Giovanni Gherdovich
> <ggherdovich@...e.cz>; linux-acpi@...r.kernel.org; linux-
> kernel@...r.kernel.org; linux-pm@...r.kernel.org
> Subject: [PATCH 2/2] ACPI: processor: idle: Remove obsolete comment
> Importance: High
> 
> Since commit 496121c02127e9c460b436244c38260b044cc45a ("ACPI:
> processor:
> idle: Allow probing on platforms with one ACPI C-state"), the comment
> doesn't reflect the code anymore; remove it.
> 
> Signed-off-by: Giovanni Gherdovich <ggherdovich@...e.cz>
> ---
>  drivers/acpi/processor_idle.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index b181f7fc2090..2a076c7a825a 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -482,10 +482,6 @@ static int acpi_processor_get_cstate_info(struct
> acpi_processor *pr)
> 
>  	pr->power.count = acpi_processor_power_verify(pr);
> 
> -	/*
> -	 * if one state of type C2 or C3 is available, mark this
> -	 * CPU as being "idle manageable"
> -	 */
>  	for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
>  		if (pr->power.states[i].valid) {
>  			pr->power.count = i;
> --
> 2.43.0

I think we can clean up a bit more. How about the patch below?

>From 115d3a07febff32eed49f9343ef111e7e1452f9d Mon Sep 17 00:00:00 2001
From: "Zhang, Rui" <rui.zhang@...el.com>
Date: Mon, 31 Mar 2025 07:29:57 +0000
Subject: [PATCH] ACPI: processor: idle: Simplify
 acpi_processor_get_cstate_info() logic

Since commit 496121c02127 ("ACPI: processor: idle: Allow probing on
platforms with one ACPI C-state"), acpi_idle driver can be probed with
C1 only.

Optimize the logic for setting pr->power.count and pr->flags.power by
1. unconditionally set pr->flags.power leveraging the fact that C1 is
   always valid after acpi_processor_get_power_info_default().
2. update acpi_processor_power_verify() to return the highest valid
   C-state directly.

No functional change intended.

Signed-off-by: Zhang Rui <rui.zhang@...el.com>
---
 drivers/acpi/processor_idle.c | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 698897b29de2..7ce8c3802937 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -442,7 +442,7 @@ static int acpi_processor_power_verify(struct acpi_processor *pr)
 
 		lapic_timer_check_state(i, pr, cx);
 		tsc_check_state(cx->type);
-		working++;
+		working = i;
 	}
 
 	if (buggy_latency) {
@@ -457,7 +457,6 @@ static int acpi_processor_power_verify(struct acpi_processor *pr)
 
 static int acpi_processor_get_cstate_info(struct acpi_processor *pr)
 {
-	unsigned int i;
 	int result;
 
 
@@ -477,17 +476,7 @@ static int acpi_processor_get_cstate_info(struct acpi_processor *pr)
 	acpi_processor_get_power_info_default(pr);
 
 	pr->power.count = acpi_processor_power_verify(pr);
-
-	/*
-	 * if one state of type C2 or C3 is available, mark this
-	 * CPU as being "idle manageable"
-	 */
-	for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
-		if (pr->power.states[i].valid) {
-			pr->power.count = i;
-			pr->flags.power = 1;
-		}
-	}
+	pr->flags.power = 1;
 
 	return 0;
 }
-- 
2.43.0