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From: Mark P. <mpe...@sq...> - 2024-11-02 02:15:31
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On Thu, Oct 31, 2024, at 12:09 AM, Mario Limonciello wrote:
> If multiple platform profile handlers have been registered, don't allow
> switching to profiles unique to only one handler.
>
> Tested-by: Matthew Schwartz <mat...@li...v>
> Signed-off-by: Mario Limonciello <mar...@am...>
> ---
> drivers/acpi/platform_profile.c | 38 +++++++++++++++++++++++++--------
> 1 file changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
> index 7bd32f1e8d834..90cbc0de4d5bc 100644
> --- a/drivers/acpi/platform_profile.c
> +++ b/drivers/acpi/platform_profile.c
> @@ -29,23 +29,43 @@ static bool platform_profile_is_registered(void)
> return !list_empty(&platform_profile_handler_list);
> }
>
> +static unsigned long platform_profile_get_choices(void)
> +{
> + struct platform_profile_handler *handler;
> + unsigned long aggregate = 0;
> + int i;
> +
> + lockdep_assert_held(&profile_lock);
> + list_for_each_entry(handler, &platform_profile_handler_list, list) {
> + unsigned long individual = 0;
> +
> + for_each_set_bit(i, handler->choices, PLATFORM_PROFILE_LAST)
> + individual |= BIT(i);
> + if (!aggregate)
> + aggregate = individual;
> + else
> + aggregate &= individual;
> + }
> +
> + return aggregate;
> +}
> +
I realise this is very unlikely but isn't it possible that the number of profiles could overflow unsigned long number of bits? As handler->choices is an array of them. It should loop through BITS_TO_LONGS(PLATFORM_PROFILE_LAST) cycles.
Also wondered if this could be simplified with setting aggregate = ~0 and then & it with each handler->choices to avoid having to scan individual bits?
> static ssize_t platform_profile_choices_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> {
> + unsigned long choices;
> int len = 0;
> int i;
>
> - scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock) {
> - if (!cur_profile)
> - return -ENODEV;
> + scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock)
> + choices = platform_profile_get_choices();
>
> - for_each_set_bit(i, cur_profile->choices, PLATFORM_PROFILE_LAST) {
> - if (len == 0)
> - len += sysfs_emit_at(buf, len, "%s", profile_names[i]);
> - else
> - len += sysfs_emit_at(buf, len, " %s", profile_names[i]);
> - }
> + for_each_set_bit(i, &choices, PLATFORM_PROFILE_LAST) {
> + if (len == 0)
> + len += sysfs_emit_at(buf, len, "%s", profile_names[i]);
> + else
> + len += sysfs_emit_at(buf, len, " %s", profile_names[i]);
> }
> len += sysfs_emit_at(buf, len, "\n");
>
> --
> 2.43.0
This links in to the later patches - but I was wondering if at profile registration/unregistration if building a local choices selection would simplify things.
Then instead of needing platform_profile_get_choices, you can just use your local choices selection to make decisions on what to show, or cycle to - instead of having to cycle thru the profiles and bits every time.
Not 100% sure how well it would work out - but might be simpler and faster?
Mark
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