linux-kernel - Re: [PATCH 02/13] leds: el15203000: Fix devm vs. non-devm ordering

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Date:   Fri, 11 Nov 2022 12:39:22 +0200
From:   Oleh Kravchenko <oleg@....org.ua>
To:     wangyufen <wangyufen@...wei.com>
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pavel Machek <pavel@....cz>,
        "weiyongjun (A)" <weiyongjun1@...wei.com>
Subject: Re: [PATCH 02/13] leds: el15203000: Fix devm vs. non-devm ordering

Hello Wang,

> 11 лист. 2022 р. о 11:21 wangyufen <wangyufen@...wei.com> написав(ла):
> 
> 
> 在 2022/11/9 18:43, Oleh Kravchenko 写道:
>> 
>> 
>>> 9 лист. 2022 р. о 12:25 wangyufen <wangyufen@...wei.com> написав(ла):
>>> 
>>> 
>>> 在 2022/11/9 17:39, Oleh Kravchenko 写道:
>>> 
>>>>> -static void el15203000_remove(struct spi_device *spi)
>>>>> 
>>>> Is remove() callback from struct spi_driver deprecated?
>>>> 
>>> It is not that remove() callback is deprecated,
>>> it's that after wrapping mutex_destroy() call with devm_add_action_or_reset(),
>>> remove() callback is unnecessary here.
>>> 
>> When remove() is called, the memory allocated by devm_*() is valid.
>> So what you try to fix here?
> 
> Fix the &priv->lock used after destroy, for details, please see patch #0
> LKML: Wang Yufen: [PATCH 00/13] leds: Fix devm vs. non-devm ordering

It doesn’t make any sense for me.
You saying that remove() called before devm_* allocation
if it true then set_brightness_delayed() will crash the system in anyway.

LED device has a parent SPI device; LED device can’t exist without SPI device.

So deallocation order should be next:
1. LED device devm_*()
2. SPI device remove()