Re: [PATCH v3 02/14] thermal: core: Rearrange checks in thermal_bind_cdev_to_trip()

lihuisong (C)
2024-08-21T08:49:56Z

在 2024/8/19 23:51, Rafael J. Wysocki 写道:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> It is not necessary to look up the thermal zone and the cooling device
> in the respective global lists to check whether or not they are
> registered. It is sufficient to check whether or not their respective
> list nodes are empty for this purpose.
>
> Use the above observation to simplify thermal_bind_cdev_to_trip(). In
> addition, eliminate an unnecessary ternary operator from it.
>
> Moreover, add lockdep_assert_held() for thermal_list_lock to it because
> that lock must be held by its callers when it is running.
>
> No intentional functional impact.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> v1 -> v3: No changes
>
> ---
> drivers/thermal/thermal_core.c | 16 ++++------------
> 1 file changed, 4 insertions(+), 12 deletions(-)
>
> Index: linux-pm/drivers/thermal/thermal_core.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_core.c
> +++ linux-pm/drivers/thermal/thermal_core.c
> @@ -781,25 +781,17 @@ int thermal_bind_cdev_to_trip(struct the
> {
> struct thermal_instance *dev;
> struct thermal_instance *pos;
> - struct thermal_zone_device *pos1;
> - struct thermal_cooling_device *pos2;
> bool upper_no_limit;
> int result;
>
> - list_for_each_entry(pos1, &thermal_tz_list, node) {
> - if (pos1 == tz)
> - break;
> - }
> - list_for_each_entry(pos2, &thermal_cdev_list, node) {
> - if (pos2 == cdev)
> - break;
> - }
> + lockdep_assert_held(&thermal_list_lock);
>
> - if (tz != pos1 || cdev != pos2)
> + if (list_empty(&tz->node) || list_empty(&cdev->node))
The old verification is ensure that tz and cdev already add to
thermal_tz_list and thermal_cdev_list，respectively.
Namely, tz and cdev are definitely registered and intialized.
The check is ok for all untizalized thermal_zone_device and cooling device.
But the new verification doesn't seem to do that.
> return -EINVAL;
>
> /* lower default 0, upper default max_state */
> - lower = lower == THERMAL_NO_LIMIT ? 0 : lower;
> + if (lower == THERMAL_NO_LIMIT)
> + lower = 0;
>
> if (upper == THERMAL_NO_LIMIT) {
> upper = cdev->max_state;
>
>
>
>
> .