Hi Arnd,
On 19. 10. 22. 오후 11:26, Arnd Bergmann wrote:
> Putting a 'struct devfreq_event_dev' object on the stack is generally
> a bad idea and here it leads to a warnig about potential stack overflow:
>
> drivers/devfreq/event/exynos-ppmu.c:643:12: error: stack frame size of 1040 bytes in function 'exynos_ppmu_probe' [-Werror,-Wframe-larger-than=]
>
> There is no real need for the device structure, only the string inside
> it, so add an internal helper function that simply takes the string
> as its argument and remove the device structure.
>
> Fixes: 1dd62c66d345 ("PM / devfreq: events: extend events by type of counted data")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> drivers/devfreq/event/exynos-ppmu.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/devfreq/event/exynos-ppmu.c b/drivers/devfreq/event/exynos-ppmu.c
> index 87b42055e6bc..302e466549d3 100644
> --- a/drivers/devfreq/event/exynos-ppmu.c
> +++ b/drivers/devfreq/event/exynos-ppmu.c
> @@ -101,17 +101,22 @@ static struct __exynos_ppmu_events {
> PPMU_EVENT(dmc1_1),
> };
>
> -static int exynos_ppmu_find_ppmu_id(struct devfreq_event_dev *edev)
> +static int __exynos_ppmu_find_ppmu_id(const char *edev_name)
> {
> int i;
>
> for (i = 0; i < ARRAY_SIZE(ppmu_events); i++)
> - if (!strcmp(edev->desc->name, ppmu_events[i].name))
> + if (!strcmp(edev_name, ppmu_events[i].name))
> return ppmu_events[i].id;
>
> return -EINVAL;
> }
>
> +static int exynos_ppmu_find_ppmu_id(struct devfreq_event_dev *edev)
> +{
> + return __exynos_ppmu_find_ppmu_id(edev->desc->name);
> +}
> +
> /*
> * The devfreq-event ops structure for PPMU v1.1
> */
> @@ -556,13 +561,11 @@ static int of_get_devfreq_events(struct device_node *np,
> * use default if not.
> */
> if (info->ppmu_type == EXYNOS_TYPE_PPMU_V2) {
> - struct devfreq_event_dev edev;
> int id;
> /* Not all registers take the same value for
> * read+write data count.
> */
> - edev.desc = &desc[j];
> - id = exynos_ppmu_find_ppmu_id(&edev);
> + id = __exynos_ppmu_find_ppmu_id(desc->name);
I got that the original exynos_ppmu_find_ppmu_id() function
has the bug. If 'events' node contains the one more events,
it will be failed. Because 'events' node only contained
the only one event on device-tree node on real use-case,
the problem had not happened.
'desc' indicates the array. So, instead of desc->name,
have to use 'desc[j].name correctly.
And I'll fix the fundamental bug on separate patch.
>
> switch (id) {
> case PPMU_PMNCNT0:
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
