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SubjectRe: [PATCH] ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit
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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@embeddedor.com>
>> ---
>> 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

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