Re: [Xen-devel] [PATCH 3/3] xmalloc: add a Kconfig option to poison free pool memory

[Jan Beulich <JBeulich@xxxxxxxx>]

On 02.07.2019 18:38, Paul Durrant wrote:
> --- a/xen/Kconfig.debug
> +++ b/xen/Kconfig.debug
> @@ -105,6 +105,13 @@ config DEBUG_TRACE
>         either directly to the console or are printed to console in case of
>         a system crash.
>   
> +config POOL_POISON

May I suggest this to become XMEM_POOL_POISON, to parallel the names
of the involved functions?

> @@ -240,6 +244,10 @@ static inline void EXTRACT_BLOCK(struct bhdr *b, struct 
> xmem_pool *p, int fl,
>           }
>       }
>       b->ptr.free_ptr = (struct free_ptr) {NULL, NULL};
> +#ifdef CONFIG_POOL_POISON
> +    for ( i = MIN_BLOCK_SIZE; i < (b->size & BLOCK_SIZE_MASK); i++ )
> +        ASSERT(b->ptr.buffer[i] == 0xAA);
> +#endif /* CONFIG_POOL_POISON */

May I further suggest that we clone Linux'es memchr_inv() for this
purpose (perhaps with a more simplistic implementation along the
lines of memchr())? We should then also use it in check_one_page().

Jan
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