It isn't required, but all callers of ipa_aggr_granularity_val()
pass a constant value (IPA_AGGR_GRANULARITY) as the usec argument.
Two of those callers are in ipa_validate_build(), with the result
being passed to BUILD_BUG_ON().
Evidently the "sparc64-linux-gcc" compiler (at least) doesn't always
inline ipa_aggr_granularity_val(), so the result of the function is
not constant at compile time, and that leads to build errors.
Define the function with the __always_inline attribute to avoid the
errors. And given that the function is inline, we can switch the
WARN_ON() there to be BUILD_BUG_ON().
Fixes: 5bc5588466a1f ("net: ipa: use WARN_ON() rather than assertions")
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Alex Elder <[email protected]>
---
David/Jakub, this fixes a bug in a commit in net-next/master. -Alex
drivers/net/ipa/ipa_main.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
index 25bbb456e0078..f90b3521e266b 100644
--- a/drivers/net/ipa/ipa_main.c
+++ b/drivers/net/ipa/ipa_main.c
@@ -255,9 +255,9 @@ ipa_hardware_config_qsb(struct ipa *ipa, const struct ipa_data *data)
* less than the number of timer ticks in the requested period. 0 is not
* a valid granularity value.
*/
-static u32 ipa_aggr_granularity_val(u32 usec)
+static __always_inline u32 ipa_aggr_granularity_val(u32 usec)
{
- WARN_ON(!usec);
+ BUILD_BUG_ON(!usec);
return DIV_ROUND_CLOSEST(usec * TIMER_FREQUENCY, USEC_PER_SEC) - 1;
}
--
2.27.0
On Tue, Aug 10, 2021 at 11:02:13AM -0500, Alex Elder wrote:
> It isn't required, but all callers of ipa_aggr_granularity_val()
> pass a constant value (IPA_AGGR_GRANULARITY) as the usec argument.
> Two of those callers are in ipa_validate_build(), with the result
> being passed to BUILD_BUG_ON().
>
> Evidently the "sparc64-linux-gcc" compiler (at least) doesn't always
> inline ipa_aggr_granularity_val(), so the result of the function is
> not constant at compile time, and that leads to build errors.
>
> Define the function with the __always_inline attribute to avoid the
> errors. And given that the function is inline, we can switch the
> WARN_ON() there to be BUILD_BUG_ON().
>
> Fixes: 5bc5588466a1f ("net: ipa: use WARN_ON() rather than assertions")
> Reported-by: kernel test robot <[email protected]>
> Signed-off-by: Alex Elder <[email protected]>
> ---
>
> David/Jakub, this fixes a bug in a commit in net-next/master. -Alex
>
> drivers/net/ipa/ipa_main.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
> index 25bbb456e0078..f90b3521e266b 100644
> --- a/drivers/net/ipa/ipa_main.c
> +++ b/drivers/net/ipa/ipa_main.c
> @@ -255,9 +255,9 @@ ipa_hardware_config_qsb(struct ipa *ipa, const struct ipa_data *data)
> * less than the number of timer ticks in the requested period. 0 is not
> * a valid granularity value.
> */
> -static u32 ipa_aggr_granularity_val(u32 usec)
> +static __always_inline u32 ipa_aggr_granularity_val(u32 usec)
> {
> - WARN_ON(!usec);
> + BUILD_BUG_ON(!usec);
So what exactly are you checking here if all callers pass same value?
It is in-kernel API, declared as static inside one module. There is no
need to protect from itself.
Thanks
>
> return DIV_ROUND_CLOSEST(usec * TIMER_FREQUENCY, USEC_PER_SEC) - 1;
> }
> --
> 2.27.0
>
On 8/11/21 7:02 AM, Leon Romanovsky wrote:
> On Tue, Aug 10, 2021 at 11:02:13AM -0500, Alex Elder wrote:
>> It isn't required, but all callers of ipa_aggr_granularity_val()
>> pass a constant value (IPA_AGGR_GRANULARITY) as the usec argument.
>> Two of those callers are in ipa_validate_build(), with the result
>> being passed to BUILD_BUG_ON().
>>
>> Evidently the "sparc64-linux-gcc" compiler (at least) doesn't always
>> inline ipa_aggr_granularity_val(), so the result of the function is
>> not constant at compile time, and that leads to build errors.
>>
>> Define the function with the __always_inline attribute to avoid the
>> errors. And given that the function is inline, we can switch the
>> WARN_ON() there to be BUILD_BUG_ON().
>>
>> Fixes: 5bc5588466a1f ("net: ipa: use WARN_ON() rather than assertions")
>> Reported-by: kernel test robot <[email protected]>
>> Signed-off-by: Alex Elder <[email protected]>
>> ---
>>
>> David/Jakub, this fixes a bug in a commit in net-next/master. -Alex
>>
>> drivers/net/ipa/ipa_main.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
>> index 25bbb456e0078..f90b3521e266b 100644
>> --- a/drivers/net/ipa/ipa_main.c
>> +++ b/drivers/net/ipa/ipa_main.c
>> @@ -255,9 +255,9 @@ ipa_hardware_config_qsb(struct ipa *ipa, const struct ipa_data *data)
>> * less than the number of timer ticks in the requested period. 0 is not
>> * a valid granularity value.
>> */
>> -static u32 ipa_aggr_granularity_val(u32 usec)
>> +static __always_inline u32 ipa_aggr_granularity_val(u32 usec)
>> {
>> - WARN_ON(!usec);
>> + BUILD_BUG_ON(!usec);
>
> So what exactly are you checking here if all callers pass same value?
> It is in-kernel API, declared as static inside one module. There is no
> need to protect from itself.
Yeah that's a good point. It can just as well be removed.
I think the check was added before I knew it was only going
to be used with a single constant value. That said, the
point was to check at runtime a required constraint.
I'll post version 2 that simply removes it. Thanks.
-Alex
>
> Thanks
>
>>
>> return DIV_ROUND_CLOSEST(usec * TIMER_FREQUENCY, USEC_PER_SEC) - 1;
>> }
>> --
>> 2.27.0
>>
On Wed, Aug 11, 2021 at 07:06:01AM -0500, Alex Elder wrote:
> On 8/11/21 7:02 AM, Leon Romanovsky wrote:
> > On Tue, Aug 10, 2021 at 11:02:13AM -0500, Alex Elder wrote:
> >> It isn't required, but all callers of ipa_aggr_granularity_val()
> >> pass a constant value (IPA_AGGR_GRANULARITY) as the usec argument.
> >> Two of those callers are in ipa_validate_build(), with the result
> >> being passed to BUILD_BUG_ON().
> >>
> >> Evidently the "sparc64-linux-gcc" compiler (at least) doesn't always
> >> inline ipa_aggr_granularity_val(), so the result of the function is
> >> not constant at compile time, and that leads to build errors.
> >>
> >> Define the function with the __always_inline attribute to avoid the
> >> errors. And given that the function is inline, we can switch the
> >> WARN_ON() there to be BUILD_BUG_ON().
> >>
> >> Fixes: 5bc5588466a1f ("net: ipa: use WARN_ON() rather than assertions")
> >> Reported-by: kernel test robot <[email protected]>
> >> Signed-off-by: Alex Elder <[email protected]>
> >> ---
> >>
> >> David/Jakub, this fixes a bug in a commit in net-next/master. -Alex
> >>
> >> drivers/net/ipa/ipa_main.c | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
> >> index 25bbb456e0078..f90b3521e266b 100644
> >> --- a/drivers/net/ipa/ipa_main.c
> >> +++ b/drivers/net/ipa/ipa_main.c
> >> @@ -255,9 +255,9 @@ ipa_hardware_config_qsb(struct ipa *ipa, const struct ipa_data *data)
> >> * less than the number of timer ticks in the requested period. 0 is not
> >> * a valid granularity value.
> >> */
> >> -static u32 ipa_aggr_granularity_val(u32 usec)
> >> +static __always_inline u32 ipa_aggr_granularity_val(u32 usec)
> >> {
> >> - WARN_ON(!usec);
> >> + BUILD_BUG_ON(!usec);
> >
> > So what exactly are you checking here if all callers pass same value?
> > It is in-kernel API, declared as static inside one module. There is no
> > need to protect from itself.
>
> Yeah that's a good point. It can just as well be removed.
> I think the check was added before I knew it was only going
> to be used with a single constant value. That said, the
> point was to check at runtime a required constraint.
>
> I'll post version 2 that simply removes it. Thanks.
Thanks
>
> -Alex
>
> >
> > Thanks
> >
> >>
> >> return DIV_ROUND_CLOSEST(usec * TIMER_FREQUENCY, USEC_PER_SEC) - 1;
> >> }
> >> --
> >> 2.27.0
> >>
>