* [PATCH] ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit
@ 2018-02-06 23:36 Gustavo A. R. Silva
2018-02-08 9:49 ` Rafael J. Wysocki
0 siblings, 1 reply; 3+ messages in thread
From: Gustavo A. R. Silva @ 2018-02-06 23:36 UTC (permalink / raw)
To: Rafael J. Wysocki, Len Brown
Cc: linux-acpi, linux-kernel, Gustavo A. R. Silva
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;
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit
2018-02-06 23:36 [PATCH] ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit Gustavo A. R. Silva
@ 2018-02-08 9:49 ` Rafael J. Wysocki
2018-02-08 16:40 ` Gustavo A. R. Silva
0 siblings, 1 reply; 3+ messages in thread
From: Rafael J. Wysocki @ 2018-02-08 9:49 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Len Brown, linux-acpi, linux-kernel, Gustavo A. R. Silva
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!
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit
2018-02-08 9:49 ` Rafael J. Wysocki
@ 2018-02-08 16:40 ` Gustavo A. R. Silva
0 siblings, 0 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2018-02-08 16:40 UTC (permalink / raw)
To: Rafael J. Wysocki, Gustavo A. R. Silva
Cc: Len Brown, linux-acpi, linux-kernel
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
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-02-06 23:36 [PATCH] ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit Gustavo A. R. Silva
2018-02-08 9:49 ` Rafael J. Wysocki
2018-02-08 16:40 ` Gustavo A. R. Silva
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