Re: [PATCH v2] jiffies: Cast to unsigned long for secs_to_jiffies() conversion

[Easwar Hariharan]

On 1/31/2025 12:52 AM, Jiri Slaby wrote:
> On 31. 01. 25, 9:30, Thomas Gleixner wrote:
>> On Fri, Jan 31 2025 at 08:06, Jiri Slaby wrote:
>>> On 30. 01. 25, 20:26, Easwar Hariharan wrote:
>>>> While converting users of msecs_to_jiffies(), lkp reported that some
>>>> range checks would always be true because of the mismatch between the
>>>> implied int value of secs_to_jiffies() vs the unsigned long
>>>> return value of the msecs_to_jiffies() calls it was replacing. Fix this
>>>> by casting secs_to_jiffies() values as unsigned long.
>>>>
>>>> Fixes: b35108a51cf7ba ("jiffies: Define secs_to_jiffies()")
>>>> CC: stable@xxxxxxxxxxxxxxx # 6.13+
>>>> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>>>> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>>>> Closes: https://lore.kernel.org/oe-kbuild-all/202501301334.NB6NszQR-
>>>> lkp@xxxxxxxxx/
>>>> Signed-off-by: Easwar Hariharan <eahariha@xxxxxxxxxxxxxxxxxxx>
>>>> ---
>>>>    include/linux/jiffies.h | 2 +-
>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
>>>> index ed945f42e064..0ea8c9887429 100644
>>>> --- a/include/linux/jiffies.h
>>>> +++ b/include/linux/jiffies.h
>>>> @@ -537,7 +537,7 @@ static __always_inline unsigned long
>>>> msecs_to_jiffies(const unsigned int m)
>>>>     *
>>>>     * Return: jiffies value
>>>>     */
>>>> -#define secs_to_jiffies(_secs) ((_secs) * HZ)
>>>> +#define secs_to_jiffies(_secs) (unsigned long)((_secs) * HZ)
>>>
>>> Could you just switch the fun to an inline instead?
>>
>> It's a macro so it can be used in static initializers.
> 
> It's the only one from the *_to_jiffies() family we offer. And I fail to
> find such a use (by a quick grep, it only might be hidden)? People
> apparently use "* HZ" in initializers...
> 
> So sure, iff there is this intention for this very one, keep it as macro.
> 

Yes, the intent is to convert those usages of "* HZ" to use
secs_to_jiffies() for better readability.

Thanks,
Easwar