linux-kernel - Re: [PATCH] mtd: nxp-spifi: decrement flash

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Date:   Wed, 9 May 2018 17:35:41 +0300
From:   Alexey Khoroshilov <khoroshilov@...ras.ru>
To:     Boris Brezillon <boris.brezillon@...tlin.com>
Cc:     Joachim Eastwood <manabian@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        ldv-project@...uxtesting.org, sil2review@...ts.osadl.org,
        Richard Weinberger <richard@....at>,
        linux-kernel@...r.kernel.org, Julia Lawall <julia.lawall@...6.fr>,
        linux-mtd@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] mtd: nxp-spifi: decrement flash_np refcnt on error paths

On 09.05.2018 12:42, Boris Brezillon wrote:
> On Tue,  8 May 2018 23:47:36 +0300
> Alexey Khoroshilov <khoroshilov@...ras.ru> wrote:
> 
>> nxp_spifi_probe() increments refcnt of SPI flash device node by
>> of_get_next_available_child() and then it passes the node
>> to mtd device in nxp_spifi_setup_flash().
>> But if a failure happens before mtd_device_register() succeed,
>> the refcnt is left undecremented.
> 
> Why not doing that in the error path of the probe function? Also, you
> probably want to call of_node_put() in the ->remove() function.
> 


You are right.

I believed that after successful mtd_device_register()
the node is managed by mtd device. I missed that it calls of_node_get()
in add_mtd_device() by itself.

I will prepare v2.
But I guess there is no need to have of_node_put() in ->remove(), since
probe() finishes its own usage of flash_np, while mtd_device incremented
refcnt by itself and will decrement it in ->remove() in
mtd_device_unregister(&spifi->nor.mtd). So, I would propose
of_node_put() on both successful and error path.

Thank you,
Alexey