2022-07-14 13:50:58

by Shivnandan Kumar

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 <[email protected]>

---
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

2022-07-14 18:53:17

by Rafael J. Wysocki

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

On Thu, Jul 14, 2022 at 3:44 PM Shivnandan Kumar
<[email protected]> wrote:
>
> 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.

The changelog doesn't match the patch any more, please rewrite it.

>
> Signed-off-by: Shivnandan Kumar <[email protected]>
>
> ---
> 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
>