[Crash-utility] [PATCH 1/2] tree: no need to bail out on tree corruption, skip the node and move on instead

[Daniel Vacek]

Hi Dave,

On Thu, Apr 12, 2018 at 3:32 PM, Dave Anderson <anderson at redhat.com> wrote:
>
> Hi Daniel,
>
> If the tree is corrupted, I would think that you would want to know the
> specifics, i.e., aside from the somewhat cryptic readmem() error message.
>
> Perhaps it would be worth printing a more meaningful error message,
> something like:
>
>   tree: rb_node: <address>: corrupt rb_left pointer: <address>

Yeah, that's a good point. I just tried a simple
s/FAULT_ON_ERROR/RETURN_ON_ERROR/ and checked if that works, but
keeping the former behaviour with regards to error reporting.

But having a meaningful error output would be nice. Do you prefer a
followup patch or amend to this one?

--nX

> That way you could do the 2 readmem() calls w/RETURN_ON_ERROR|QUIET, and
> just have the concise error message.
>
> Thanks,
>   Dave
>
> ----- Original Message -----
>> ---
>>  tools.c | 23 ++++++++++++-----------
>>  1 file changed, 12 insertions(+), 11 deletions(-)
>>
>> diff --git a/tools.c b/tools.c
>> index 186b703463a5..992f4776281a 100644
>> --- a/tools.c
>> +++ b/tools.c
>> @@ -4374,8 +4374,8 @@ rbtree_iteration(ulong node_p, struct tree_data *td,
>> char *pos)
>>  {
>>       int i;
>>       uint print_radix;
>> -     ulong struct_p, left_p, right_p;
>> -     char left_pos[BUFSIZE], right_pos[BUFSIZE];
>> +     ulong struct_p, new_p;
>> +     char new_pos[BUFSIZE];
>>       static struct req_entry **e;
>>
>>       if (!node_p)
>> @@ -4430,16 +4430,17 @@ rbtree_iteration(ulong node_p, struct tree_data *td,
>> char *pos)
>>               }
>>       }
>>
>> -     readmem(node_p+OFFSET(rb_node_rb_left), KVADDR, &left_p,
>> -             sizeof(void *), "rb_node rb_left", FAULT_ON_ERROR);
>> -     readmem(node_p+OFFSET(rb_node_rb_right), KVADDR, &right_p,
>> -             sizeof(void *), "rb_node rb_right", FAULT_ON_ERROR);
>> -
>> -     sprintf(left_pos, "%s/l", pos);
>> -     sprintf(right_pos, "%s/r", pos);
>> +     if (    readmem(node_p+OFFSET(rb_node_rb_left), KVADDR, &new_p,
>> +                     sizeof(void *), "rb_node rb_left", RETURN_ON_ERROR)) {
>> +             sprintf(new_pos, "%s/l", pos);
>> +             rbtree_iteration(new_p, td, new_pos);
>> +     }
>>
>> -     rbtree_iteration(left_p, td, left_pos);
>> -     rbtree_iteration(right_p, td, right_pos);
>> +     if (    readmem(node_p+OFFSET(rb_node_rb_right), KVADDR, &new_p,
>> +                     sizeof(void *), "rb_node rb_right", RETURN_ON_ERROR)) {
>> +             sprintf(new_pos, "%s/r", pos);
>> +             rbtree_iteration(new_p, td, new_pos);
>> +     }
>>  }
>>
>>  void
>> --
>> 2.16.2
>>
>> --
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