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SubjectRe: [PATCH 01/13] seqnum_ops: Introduce Sequence Number Ops
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On 11/11/20 12:23 PM, Shuah Khan wrote:
> On 11/10/20 5:18 PM, Kees Cook wrote:
>> On Tue, Nov 10, 2020 at 09:43:02PM +0100, Greg KH wrote:
>>> On Tue, Nov 10, 2020 at 09:41:40PM +0100, Greg KH wrote:
>>>> On Tue, Nov 10, 2020 at 12:53:27PM -0700, Shuah Khan wrote:
>>>>> +Decrement interface
>>>>> +-------------------
>>>>> +
>>>>> +Decrements sequence number and doesn't return the new value. ::
>>>>> +
>>>>> +        seqnum32_dec() --> atomic_dec()
>>>>> +        seqnum64_dec() --> atomic64_dec()
>>>>
>>>> Why would you need to decrement a sequence number?  Shouldn't they just
>>>> always go up?
>>>>
>>>> I see you use them in your patch 12/13, but I don't think that
>>>> really is
>>>> a sequence number there, but rather just some other odd value :)
>>
>> To that end, they should likely be internally cast to u32 and u64 (and
>> why is seqnum64 ifdef on CONFIG_64BIT?).
>>
>

atomic64_t depends on CONFIG_64BIT

include/linux/types.h

#ifdef CONFIG_64BIT
typedef struct {
s64 counter;
} atomic64_t;
#endif

thanks,
-- Shuah

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