linux-kernel - Re: [PATCH] mtd: add reboot notifier to mtdcore and register nand

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Message-ID: <5480F88D.4090707@broadcom.com>
Date:	Thu, 4 Dec 2014 16:13:01 -0800
From:	Scott Branden <sbranden@...adcom.com>
To:	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>
CC:	Ray Jui <rjui@...adcom.com>, Corneliu Doban <cdoban@...adcom.com>,
	<linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mtd: add reboot notifier to mtdcore and register nand_shutdown
 with notifier

Apologies:  patch fails checkpatch due to spaces instead of tabs during 
cut and paste.

But, please comment on this patch before I create a new version.

On 14-12-04 02:37 PM, Scott Branden wrote:
> add (optional) reboot notifier field to struct mtd_info, and use it to
> register a system reboot notifier on behalf of the lower layers.
>
> Add nand_shutdown to wait for current nand operations to finish and prevent
> further operations by changing the nand flash state to FL_SHUTDOWN.
> Register the nand_shutdown with the reboot notifier in nand_base.c
>
> This is addressing a problem observed during reboot tests using UBIFS
> root file system: NAND erase operations that are in progress during
> system reboot/shutdown are causing partial erased blocks. Although UBI should
> be able to detect and recover from this error, this change will avoid
> the creation of partial erased blocks on reboot in the middle of a NAND erase
> operation.
>
> Signed-off-by: Brian Norris <computersforpeace@...il.com>
> Signed-off-by: Corneliu Doban <cdoban@...adcom.com>
> Signed-off-by: Scott Branden <sbranden@...adcom.com>
> ---
>   drivers/mtd/mtdcore.c        | 20 ++++++++++++++++++++
>   drivers/mtd/nand/nand_base.c | 11 +++++++++++
>   include/linux/mtd/mtd.h      |  1 +
>   3 files changed, 32 insertions(+)
>
> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
> index 4c61187..b80d44f 100644
> --- a/drivers/mtd/mtdcore.c
> +++ b/drivers/mtd/mtdcore.c
> @@ -37,6 +37,7 @@
>   #include <linux/backing-dev.h>
>   #include <linux/gfp.h>
>   #include <linux/slab.h>
> +#include <linux/reboot.h>
>
>   #include <linux/mtd/mtd.h>
>   #include <linux/mtd/partitions.h>
> @@ -365,6 +366,17 @@ static struct device_type mtd_devtype = {
>   	.release	= mtd_release,
>   };
>
> +static int mtd_reboot_notifier(struct notifier_block *n, unsigned long state,
> +			       void *cmd)
> +{
> +       struct mtd_info *mtd;
> +
> +       mtd = container_of(n, struct mtd_info, reboot_notifier);
> +       mtd->_reboot(mtd);
> +
> +       return NOTIFY_DONE;
> +}
> +
>   /**
>    *	add_mtd_device - register an MTD device
>    *	@mtd: pointer to new MTD device info structure
> @@ -565,6 +577,11 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
>   			err = -ENODEV;
>   	}
>
> +	if (mtd->_reboot) {
> +		mtd->reboot_notifier.notifier_call = mtd_reboot_notifier;
> +		register_reboot_notifier(&mtd->reboot_notifier);
> +	}
> +
>   	return err;
>   }
>   EXPORT_SYMBOL_GPL(mtd_device_parse_register);
> @@ -579,6 +596,9 @@ int mtd_device_unregister(struct mtd_info *master)
>   {
>   	int err;
>
> +	if (master->_reboot)
> +		unregister_reboot_notifier(&master->reboot_notifier);
> +
>   	err = del_mtd_partitions(master);
>   	if (err)
>   		return err;
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index 5b5c627..e18165b 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -2944,6 +2944,16 @@ static void nand_resume(struct mtd_info *mtd)
>   			__func__);
>   }
>
> +/**
> + * nand_shutdown - [MTD Interface] Finish the current NAND operation and
> + *                 prevent further operations
> + * @mtd: MTD device structure
> + */
> +static void nand_shutdown(struct mtd_info *mtd)
> +{
> +	nand_get_device(mtd, FL_SHUTDOWN);
> +}
> +
>   /* Set default functions */
>   static void nand_set_defaults(struct nand_chip *chip, int busw)
>   {
> @@ -4146,6 +4156,7 @@ int nand_scan_tail(struct mtd_info *mtd)
>   	mtd->_unlock = NULL;
>   	mtd->_suspend = nand_suspend;
>   	mtd->_resume = nand_resume;
> +	mtd->_reboot = nand_shutdown;
>   	mtd->_block_isreserved = nand_block_isreserved;
>   	mtd->_block_isbad = nand_block_isbad;
>   	mtd->_block_markbad = nand_block_markbad;
> diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
> index 031ff3a..c06f537 100644
> --- a/include/linux/mtd/mtd.h
> +++ b/include/linux/mtd/mtd.h
> @@ -227,6 +227,7 @@ struct mtd_info {
>   	int (*_block_markbad) (struct mtd_info *mtd, loff_t ofs);
>   	int (*_suspend) (struct mtd_info *mtd);
>   	void (*_resume) (struct mtd_info *mtd);
> +	void (*_reboot) (struct mtd_info *mtd);
>   	/*
>   	 * If the driver is something smart, like UBI, it may need to maintain
>   	 * its own reference counting. The below functions are only for driver.
>

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