[Crash-utility] do_radix_tree() function in filesys.c

[Dave Anderson]

Alan Tyson wrote:
> I notice that there is a function to look at radix trees in filesys.c, 
> but it's not called by anything in the crash executable from what I can 
> see.  In fact when I wrote a small extension to call it, I see that it 
> simply doesn't work for several reasons (wrong structures, incorrect 
> dereferencing of pointers).  Attached is a patch which addresses these.  
> I've tested it on i686, x86_64 and ia64.
> 
> If you think that this type of ("utility") code is best left out of 
> crash, then let's just remove this from the source and not clutter it 
> with dead code.  Personally, I think it's nice to have it there... when 
> it works.
> 

I don't care either way any more, but since you've made it work
again, I'll queue your changes for the next release.

Thanks,
   Dave


> Regards,
> 
> Alan Tyson, HP.
> 
> 
> ------------------------------------------------------------------------
> 
> --- a/filesys.c	2008-01-11 19:35:32.000000000 +0000
> +++ b/filesys.c	2008-01-21 16:21:20.000000000 +0000
> @@ -3484,10 +3484,14 @@ cleanup_memory_driver(void)
>  #define RADIX_TREE_MAP_SHIFT  6
>  #define RADIX_TREE_MAP_SIZE  (1UL << RADIX_TREE_MAP_SHIFT)
>  #define RADIX_TREE_MAP_MASK  (RADIX_TREE_MAP_SIZE-1)
> +#define RADIX_TREE_TAGS         2
> +#define RADIX_TREE_TAG_LONGS    \
> +	((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
>  
>  struct radix_tree_node {
>          unsigned int    count;
>          void            *slots[RADIX_TREE_MAP_SIZE];
> +	unsigned long	tags[RADIX_TREE_TAGS][RADIX_TREE_TAG_LONGS];
>  };
>  
>  /*
> @@ -3639,16 +3643,15 @@ static void *
>  radix_tree_lookup(ulong root_rnode, ulong index, int height)
>  {
>  	unsigned int shift;
> -	struct radix_tree_node **slot;
> +	void *slot;
>  	struct radix_tree_node slotbuf;
> -	void **kslotp, **uslotp;
>  
>  	shift = (height-1) * RADIX_TREE_MAP_SHIFT;
> -	kslotp = (void **)root_rnode;
> +
> +	readmem(root_rnode, KVADDR, &slot, sizeof(void *),
> +		"radix_tree_root rnode", FAULT_ON_ERROR);
>  
>  	while (height > 0) {
> -		readmem((ulong)kslotp, KVADDR, &slot, sizeof(void *),
> -			"radix_tree_node slot", FAULT_ON_ERROR);
>  
>  		if (slot == NULL)
>  			return NULL;
> @@ -3657,15 +3660,13 @@ radix_tree_lookup(ulong root_rnode, ulon
>  			sizeof(struct radix_tree_node),
>  			"radix_tree_node struct", FAULT_ON_ERROR);
>  
> -		uslotp = (void **)
> -		    (slotbuf.slots + ((index >> shift) & RADIX_TREE_MAP_MASK));
> -		kslotp = *uslotp;
> -
> +		slot = slotbuf.slots[((index >> shift) & RADIX_TREE_MAP_MASK)];
> +		
>  		shift -= RADIX_TREE_MAP_SHIFT;
>  		height--;
>  	}
>  
> -	return (void *) kslotp;
> +	return slot;
>  }
>  
>  int
> 
> 
> ------------------------------------------------------------------------
> 
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