[RFC][PATCH 2/2 -mm] kexec based hibernation: kexec restore

[Pavel Machek]

Hi!

> This patch adds writing support for /dev/oldmem. This is used to
> restore the memory contents of hibernated system.
> 
> Signed-off-by: Huang Ying <ying.huang at intel.com>

> +ssize_t write_oldmem_page(unsigned long pfn, const char *buf,
> +			  size_t csize, unsigned long offset, int userbuf)

Hmm, int userbuf is only ever set to one... Does it make sense to have
write_oldmem_page in the separate file? The onl user is mem.c, perhaps
it should go there?

> +
> +/*
> + * Write memory corresponding to the old kernel.
> + */
> +static ssize_t write_oldmem(struct file *file, const char __user *buf,
> +			    size_t count, loff_t *ppos)
> +{
> +	unsigned long pfn, offset;
> +	size_t write = 0, csize;
> +	int rc = 0;
> +
> +	while (count) {
> +		pfn = *ppos / PAGE_SIZE;
> +		if (pfn > saved_max_pfn)
> +			return write;
> +
> +		offset = (unsigned long)(*ppos % PAGE_SIZE);
> +		if (count > PAGE_SIZE - offset)
> +			csize = PAGE_SIZE - offset;
> +		else
> +			csize = count;
> +		rc = write_oldmem_page(pfn, buf, csize, offset, 1);
> +		if (rc < 0)
> +			return rc;
> +		buf += csize;
> +		*ppos += csize;
> +		write += csize;
> +		count -= csize;
> +	}
> +	return write;
> +}

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