[Mesa-dev] [PATCH 1/9] util: fix undefined behavior

[Tolga Dalman]

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Hi,


On 02.04.2012 00:24, nobled wrote:
>  #define LIST_FOR_EACH_ENTRY(pos, head, member)				\
> -   for (pos = container_of((head)->next, pos, member);			\
> +   for (pos = NULL, pos = container_of((head)->next, pos, member);	\
>  	&pos->member != (head);						\
>  	pos = container_of(pos->member.next, pos, member))

The container_of macro is obviously error-prone and leads to future
problems. Your patch works around that buggy API instead of 
really fixing it.

container_of could be defined using the offsetof macro, i.e.,

#define container_of(ptr, type, member) \
  (void *)((char *)(ptr) - offsetof(type, member))

As far as I can see, container_of is only used sparsely in
mesa, so applying my proposal should be possible quite easily.

Best regards
Tolga Dalman
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