linux-kernel - Re: [PATCH v3 02/14] thermal: core: Rearrange checks in thermal_bind_cdev_to

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Message-ID: <CAJZ5v0jHs41Xswdk+g_=mT6NGWL47tzUnHECFgo5TCp7i7ZZUw@mail.gmail.com>
Date: Wed, 21 Aug 2024 13:12:01 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: "lihuisong (C)" <lihuisong@...wei.com>
Cc: Daniel Lezcano <daniel.lezcano@...aro.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, 
	LKML <linux-kernel@...r.kernel.org>, Lukasz Luba <lukasz.luba@....com>, 
	Zhang Rui <rui.zhang@...el.com>, Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v3 02/14] thermal: core: Rearrange checks in thermal_bind_cdev_to_trip()

On Wed, Aug 21, 2024 at 1:11 PM lihuisong (C) <lihuisong@...wei.com> wrote:
>
>
> 在 2024/8/21 17:28, Daniel Lezcano 写道:
> > On 21/08/2024 10:49, lihuisong (C) wrote:
> >
> > [ ... ]
> >
> >>> -    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.
> >
> > If the tz or the cdev are registered then their "->node" is not empty
> > because they are linked with the thermal_list and cdev_list
> >
> > So either way is browsing the lists to find the tz/cdev or just check
> > "->node" is not empty. The latter the faster.
> Assume that tz/cdev isn't intiazlized and registered to thermal_tz_list
> or thermal_cdev_list. And then directly call this interface.

Who does this?