linux-kernel - [PATCH 3.10 025/139] cpufreq: conservative: Allow down

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Message-Id: <1509571159-4405-26-git-send-email-w@1wt.eu>
Date:   Wed,  1 Nov 2017 22:17:25 +0100
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Tomasz Wilczyński <twilczynski@...er.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 025/139] cpufreq: conservative: Allow down_threshold to take values from 1 to 10

From: Tomasz Wilczyński <twilczynski@...er.com>

commit b8e11f7d2791bd9320be1c6e772a60b2aa093e45 upstream.

Commit 27ed3cd2ebf4 (cpufreq: conservative: Fix the logic in frequency
decrease checking) removed the 10 point substraction when comparing the
load against down_threshold but did not remove the related limit for the
down_threshold value.  As a result, down_threshold lower than 11 is not
allowed even though values from 1 to 10 do work correctly too. The
comment ("cannot be lower than 11 otherwise freq will not fall") also
does not apply after removing the substraction.

For this reason, allow down_threshold to take any value from 1 to 99
and fix the related comment.

Fixes: 27ed3cd2ebf4 (cpufreq: conservative: Fix the logic in frequency decrease checking)
Signed-off-by: Tomasz Wilczyński <twilczynski@...er.com>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Cc: 3.10+ <stable@...r.kernel.org> 
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/cpufreq/cpufreq_conservative.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index f97cb3d..f34e819 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -212,8 +212,8 @@ static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
 	int ret;
 	ret = sscanf(buf, "%u", &input);
 
-	/* cannot be lower than 11 otherwise freq will not fall */
-	if (ret != 1 || input < 11 || input > 100 ||
+	/* cannot be lower than 1 otherwise freq will not fall */
+	if (ret != 1 || input < 1 || input > 100 ||
 			input >= cs_tuners->up_threshold)
 		return -EINVAL;
 
-- 
2.8.0.rc2.1.gbe9624a