Re: [PATCH] ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit

[Gustavo A. R. Silva]

On 02/08/2018 03:49 AM, Rafael J. Wysocki wrote:
> On Wednesday, February 7, 2018 12:36:17 AM CET Gustavo A. R. Silva wrote:
> > Add suffix ULL to constant 500 in order to give the compiler complete
> > information about the proper arithmetic to use. Notice that this
> > constant is used in a context that expects an expression of type
> > u64 (64 bits, unsigned).
> >
> > The expression NUM_RETRIES * cppc_ss->latency at line 578, which at
> > preprocessing time translates to 500 * cppc_ss->latency is currently
> > being evaluated using 32-bit arithmetic.
> >
> > Addresses-Coverity-ID: 1382602
> > Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> > ---
> > Notice that another option is to cast NUM_RETRIES to u64 at line 578,
> > but as there is only one instace in which this macro is being used I
> > think adding the ULL is just enough.
> >
> >   drivers/acpi/cppc_acpi.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> > index 06ea474..0afbb26 100644
> > --- a/drivers/acpi/cppc_acpi.c
> > +++ b/drivers/acpi/cppc_acpi.c
> > @@ -119,7 +119,7 @@ static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
> >    * to PCC commands. Keeping it high enough to cover emulators where
> >    * the processors run painfully slow.
> >    */
> > -#define NUM_RETRIES 500
> > +#define NUM_RETRIES 500ULL
> >   
> >   struct cppc_attr {
> >   	struct attribute attr;
>
> Applied, thanks!

Thank you, Rafael.

--
Gustavo