linux-kernel - Re: [PATCHv6 2/5] lib/genalloc.c: Add genpool range check function

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Date:	Fri, 8 Aug 2014 15:40:08 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Laura Abbott <lauraa@...eaurora.org>
Cc:	Will Deacon <will.deacon@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Russell King <linux@....linux.org.uk>,
	David Riley <davidriley@...omium.org>,
	linux-arm-kernel@...ts.infradead.org,
	Ritesh Harjain <ritesh.harjani@...il.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Thierry Reding <thierry.reding@...il.com>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCHv6 2/5] lib/genalloc.c: Add genpool range check function

On Fri,  8 Aug 2014 13:23:14 -0700 Laura Abbott <lauraa@...eaurora.org> wrote:

> 
> After allocating an address from a particular genpool,
> there is no good way to verify if that address actually
> belongs to a genpool. Introduce addr_in_gen_pool which
> will return if an address plus size falls completely
> within the genpool range.
> 
> ...
>
>  /**
> + * addr_in_gen_pool - checks if an address falls within the range of a pool
> + * @pool:	the generic memory pool
> + * @start:	start address
> + * @size:	size of the region
> + *
> + * Check if the range of addresses falls within the specified pool.

This description should make it clear that the entire range must be
within the pool - that an overlap is "no".

>     Takes
> + * the rcu_read_lock for the duration of the check.

I don't think this part is worth including.

> + */
> +bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
> +			size_t size)
> +{
> +	bool found = false;
> +	unsigned long end = start + size;
> +	struct gen_pool_chunk *chunk;
> +
> +	rcu_read_lock();
> +	list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
> +		if (start >= chunk->start_addr && start <= chunk->end_addr) {
> +			if (end <= chunk->end_addr) {
> +				found = true;
> +				break;
> +			}
> +		}
> +	}
> +	rcu_read_unlock();
> +	return found;
> +}

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