linux-kernel - Re: [PATCH v4 01/58] mtd: nand: denali: add missing nand_release() call in denali

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Message-ID: <20151211004008.GQ144338@google.com>
Date:	Thu, 10 Dec 2015 16:40:08 -0800
From:	Brian Norris <computersforpeace@...il.com>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:	David Woodhouse <dwmw2@...radead.org>,
	linux-mtd@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
	Hartley Sweeten <hsweeten@...ionengravers.com>,
	Ryan Mallon <rmallon@...il.com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <kernel@...gutronix.de>,
	Imre Kaloz <kaloz@...nwrt.org>,
	Krzysztof Halasa <khalasa@...p.pl>,
	Tony Lindgren <tony@...mide.com>, linux-omap@...r.kernel.org,
	Alexander Clouter <alex@...riz.org.uk>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Gregory CLEMENT <gregory.clement@...e-electrons.com>,
	Jason Cooper <jason@...edaemon.net>,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	Andrew Lunn <andrew@...n.ch>, Daniel Mack <daniel@...que.org>,
	Haojian Zhuang <haojian.zhuang@...il.com>,
	Robert Jarzmik <robert.jarzmik@...e.fr>,
	Marek Vasut <marek.vasut@...il.com>,
	Steven Miao <realmz6@...il.com>,
	adi-buildroot-devel@...ts.sourceforge.net,
	Mikael Starvik <starvik@...s.com>,
	Jesper Nilsson <jesper.nilsson@...s.com>,
	linux-cris-kernel@...s.com, Josh Wu <josh.wu@...el.com>,
	Wan ZongShun <mcuos.com@...il.com>,
	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
	Maxim Levitsky <maximlevitsky@...il.com>,
	Kukjin Kim <kgene@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	linux-samsung-soc@...r.kernel.org,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Chen-Yu Tsai <wens@...e.org>, linux-sunxi@...glegroups.com,
	Stefan Agner <stefan@...er.ch>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	devel@...verdev.osuosl.org, stable@...r.kernel.org
Subject: Re: [PATCH v4 01/58] mtd: nand: denali: add missing nand_release()
 call in denali_remove()

On Thu, Dec 10, 2015 at 08:59:45AM +0100, Boris Brezillon wrote:
> Unregister the NAND device from the NAND subsystem when removing a denali
> NAND controller, otherwise the MTD attached to the NAND device is still
> exposed by the MTD layer, and accesses to this device will likely crash
> the system.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> Cc: <stable@...r.kernel.org> #3.8+

Does this follow these rules, from
Documentation/stable_kernel_rules.txt?

 - It must be obviously correct and tested.

 - It must fix a real bug that bothers people (not a, "This could be a
   problem..." type thing).

> Fixes: 2a0a288ec258 ("mtd: denali: split the generic driver and PCI layer")
> ---
>  drivers/mtd/nand/denali.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
> index 67eb2be..8feece3 100644
> --- a/drivers/mtd/nand/denali.c
> +++ b/drivers/mtd/nand/denali.c
> @@ -1622,6 +1622,7 @@ EXPORT_SYMBOL(denali_init);
>  /* driver exit point */
>  void denali_remove(struct denali_nand_info *denali)
>  {
> +	nand_release(&denali->mtd);
>  	denali_irq_cleanup(denali->irq, denali);
>  	dma_unmap_single(denali->dev, denali->buf.dma_buf,
>  			 denali->mtd.writesize + denali->mtd.oobsize,

It feels a bit odd to allow usage of MTD fields after it has been
unregistered. Maybe precompute this before the nand_release()?

Brian
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