linux-kernel - [PATCH v2 1/1] PM: QoS: Add check to make sure CPU freq is non-negative

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Date:   Thu, 14 Jul 2022 19:13:42 +0530
From:   Shivnandan Kumar <quic_kshivnan@...cinc.com>
To:     <rafael@...nel.org>, <len.brown@...el.com>, <pavel@....cz>
CC:     <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Shivnandan Kumar" <quic_kshivnan@...cinc.com>
Subject: [PATCH v2 1/1] PM: QoS: Add check to make sure CPU freq is non-negative

	CPU frequency should never be negative.
	If some client driver calls freq_qos_update_request with some
	value greater than INT_MAX, then it will set max CPU freq at
	fmax but it will add plist node with some negative priority.
	plist node has priority from INT_MIN (highest) to INT_MAX
	(lowest). Once priority is set as negative, another client
	will not be able to reduce CPU frequency. Adding check to
	make sure CPU freq is non-negative will fix this problem.

Signed-off-by: Shivnandan Kumar <quic_kshivnan@...cinc.com>

---
v1->v2
	-addressed comments from Rafael
	-changed commit text accordingly

 kernel/power/qos.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index ec7e1e85923e..27e6596f287a 100644
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -531,7 +531,7 @@ int freq_qos_add_request(struct freq_constraints *qos,
 {
 	int ret;
 
-	if (IS_ERR_OR_NULL(qos) || !req)
+	if (IS_ERR_OR_NULL(qos) || !req || value < FREQ_QOS_MIN_DEFAULT_VALUE)
 		return -EINVAL;
 
 	if (WARN(freq_qos_request_active(req),
@@ -563,7 +563,7 @@ EXPORT_SYMBOL_GPL(freq_qos_add_request);
  */
 int freq_qos_update_request(struct freq_qos_request *req, s32 new_value)
 {
-	if (!req)
+	if (!req || new_value < FREQ_QOS_MIN_DEFAULT_VALUE)
 		return -EINVAL;
 
 	if (WARN(!freq_qos_request_active(req),
-- 
2.25.1