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Subject: Re: Patch "spi: Fix controller unregister order" has been added to
 the 4.4-stable tree
To:     <linux-kernel@vger.kernel.org>, <lukas@wunner.de>,
        <sashal@kernel.org>, <chenwenyong2@huawei.com>
CC:     <stable-commits@vger.kernel.org>,
        "zhangyi (F)" <yi.zhang@huawei.com>
References: <20200616015646.AC54E2074D@mail.kernel.org>
From:   yangerkun <yangerkun@huawei.com>
Message-ID: <8c7683cc-ca73-6883-8e45-613de68fa665@huawei.com>
Date:   Sat, 10 Oct 2020 16:41:09 +0800
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?? 2020/6/16 9:56, Sasha Levin д??:
> This is a note to let you know that I've just added the patch titled
> 
>      spi: Fix controller unregister order
> 
> to the 4.4-stable tree which can be found at:
>      http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> 
> The filename of the patch is:
>       spi-fix-controller-unregister-order.patch
> and it can be found in the queue-4.4 subdirectory.
> 
> If you, or anyone else, feels it should not be added to the stable tree,
> please let <stable@vger.kernel.org> know about it.
> 
> 
> 
> commit af9adff04d45f726c49bc1be4a401877e627adf3
> Author: Lukas Wunner <lukas@wunner.de>
> Date:   Fri May 15 17:58:01 2020 +0200
> 
>      spi: Fix controller unregister order
>      
>      [ Upstream commit 84855678add8aba927faf76bc2f130a40f94b6f7 ]
>      
>      When an SPI controller unregisters, it unbinds all its slave devices.
>      For this, their drivers may need to access the SPI bus, e.g. to quiesce
>      interrupts.
>      
>      However since commit ffbbdd21329f ("spi: create a message queueing
>      infrastructure"), spi_destroy_queue() is executed before unbinding the
>      slaves.  It sets ctlr->running = false, thereby preventing SPI bus
>      access and causing unbinding of slave devices to fail.
>      
>      Fix by unbinding slaves before calling spi_destroy_queue().
>      
>      Fixes: ffbbdd21329f ("spi: create a message queueing infrastructure")
>      Signed-off-by: Lukas Wunner <lukas@wunner.de>
>      Cc: stable@vger.kernel.org # v3.4+
>      Cc: Linus Walleij <linus.walleij@linaro.org>
>      Link: https://lore.kernel.org/r/8aaf9d44c153fe233b17bc2dec4eb679898d7e7b.1589557526.git.lukas@wunner.de
>      Signed-off-by: Mark Brown <broonie@kernel.org>
>      Signed-off-by: Sasha Levin <sashal@kernel.org>
> 
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index e5460d84ed08..57001f8f727a 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -1922,11 +1922,12 @@ void spi_unregister_master(struct spi_master *master)
>   			dev_err(&master->dev, "queue remove failed\n");
>   	}
>   
> +	device_for_each_child(&master->dev, NULL, __unregister);
> +

Hi,

This is a wrong patch. We should move this line before
spi_destroy_queue, but we didn't. 4.9 stable exists this
problem too.

Thanks,
Kun.


>   	mutex_lock(&board_lock);
>   	list_del(&master->list);
>   	mutex_unlock(&board_lock);
>   
> -	device_for_each_child(&master->dev, NULL, __unregister);
>   	device_unregister(&master->dev);
>   }
>   EXPORT_SYMBOL_GPL(spi_unregister_master);
> 
> .
>