Re: [XenPPC] [RFC] fix stupid grant table flags

[Jimi Xenidis <jimix@xxxxxxxxxxxxxx>]

I don't think you definition of clear_entry_flag will work, see below

On Jun 21, 2006, at 2:49 PM, Hollis Blanchard wrote:
> diff -r ab08d443113d xen/include/asm-ppc/grant_table.h
> --- a/xen/include/asm-ppc/grant_table.h Wed Jun 21 13:36:49 2006 -0500
> +++ b/xen/include/asm-ppc/grant_table.h Wed Jun 21 13:42:23 2006 -0500
> @@ -6,4 +6,6 @@
>  #define mark_dirty(d, f) ((void )0)
>  #include "../asm-x86/grant_table.h"
>
> +#define clear_entry_flag(nr, flags) clear_bit((nr), (int *)(flags));
1) clear_bit takes an 'unsigned long *' so this should have cause a  
warning
2) bitops are designed to find the ulong array element (nr /  
BITS_PER_LONG) then set the bit like (1 << (nr % BITS_PER_LONG)) so  
that the word feels like 'C' order.
So I think the definition should be:
  static inline void  clear_entry_flag(unsigned long nr, volatile  
uint16_t *addr) {
      volatile unsigned long *laddr;
      unsigned long lnr;
  #ifdef SAFETY_DANCE
      BUG_ON((ulong)addr % sizeof (ulong));
  #endif
      lnr = (BITS_PER_LONG - (sizeof (*addr) * 8)) + nr;
      laddr = (volatile unsigned long *)addr;
      clear_bit(lnr, laddr);
  }

You could macro-tize this, but why.

-JX


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