Re: [Xen-devel] [PATCH] incorrect xfree for mini-os

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>]

INAKOSHI Hiroya, le Wed 02 Apr 2008 19:43:29 +0900, a écrit :
> xfree in extras/mini-os/lib/xmalloc.c is incorrect.
> 
> It has to check first if the memory to free is so big as to be freed
> directly by free_pages.
> 
> mini-os domains crash without this patch if they don't configure vfb
> correctly.
> 
> Signed-off-by: INAKOSHI Hiroya <inakoshi.hiroya@xxxxxxxxxxxxxx>

Acked-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>

> diff -r db943e8d1051 extras/mini-os/lib/xmalloc.c
> --- a/extras/mini-os/lib/xmalloc.c    Tue Apr 01 10:09:33 2008 +0100
> +++ b/extras/mini-os/lib/xmalloc.c    Wed Apr 02 19:34:40 2008 +0900
> @@ -208,6 +208,13 @@ void xfree(const void *p)
>      pad = (struct xmalloc_pad *)p - 1;
>      hdr = (struct xmalloc_hdr *)((char *)p - pad->hdr_size);
>  
> +    /* Big allocs free directly. */
> +    if ( hdr->size >= PAGE_SIZE )
> +    {
> +        free_pages(hdr, get_order(hdr->size));
> +        return;
> +    }
> +
>      /* We know hdr will be on same page. */
>      if(((long)p & PAGE_MASK) != ((long)hdr & PAGE_MASK))
>      {
> @@ -220,13 +227,6 @@ void xfree(const void *p)
>      {
>          printk("Should not be previously freed\n");
>          *(int*)0=0;
> -    }
> -
> -    /* Big allocs free directly. */
> -    if ( hdr->size >= PAGE_SIZE )
> -    {
> -        free_pages(hdr, get_order(hdr->size));
> -        return;
>      }
>  
>      /* Merge with other free block, or put in list. */

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-- 
Samuel
* x remarque qu'avec un peu de volonté, on peut faire du code de porc
dans d'importe quel langage Turing-complet
 -+- x sur #ens-mim - codons porc -+-

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