[lustre-devel] [PATCH 24/24] lustre: discard TCD_MAX_TYPES

[NeilBrown]

On Sun, Jun 24 2018, James Simmons wrote:

>> As well as CFS_TCD_TYPE_CNT we have TCD_MAX_TYPES which has a larger
>> value but a similar meaning.  Discard it and just use
>> CFS_TCD_TYPE_CNT.
>> 
>> Two places relied on the fact that TCD_MAX_TYPES was larger and so
>> there would be NULLs at the end of the array.  Change
>> them to check the array size properly.
>> 
>> Signed-off-by: NeilBrown <neilb at suse.com>
>> ---
>> 
>> Thanks for testing James!
>> I found two problems.
>> 1/ I had
>> -       for (i = 0; cfs_trace_data[i] && i < CFS_TCD_TYPE_CNT; i++) {
>> instead of
>> +       for (i = 0; i < CFS_TCD_TYPE_CNT && cfs_trace_data[i]; i++) {
>> 
>> So it could dereference beyond the end of an array.  I don't this was
>> the problem.
>> 
>> 2/ I hadn't changed
>> -       for (i = 0; cfs_trace_data[i]; i++)                             \
>> to
>> +       for (i = 0; i < CFS_TCD_TYPE_CNT && cfs_trace_data[i]; i++)                             \
>> 
>> so if cfs_trace_data[4] was non NULL, bad things could happen.
>> I suspect this is what happened to you.
>> 
>> Thanks,
>> NeilBrown
>
> Much better :-)

Thanks for the confirmation!

NeilBrown
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