Add gcc attribute unused for `cpumsr` variable.
Fix warnings treated as errors with W=1:
arch/powerpc/kernel/process.c:231:16: error: variable ‘cpumsr’ set but not used [-Werror=unused-but-set-variable]
arch/powerpc/kernel/process.c:296:16: error: variable ‘cpumsr’ set but not used [-Werror=unused-but-set-variable]
Signed-off-by: Mathieu Malaterre <[email protected]>
---
arch/powerpc/kernel/process.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 96f34730010f..b9f1a2408738 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -228,7 +228,7 @@ EXPORT_SYMBOL_GPL(flush_fp_to_thread);
void enable_kernel_fp(void)
{
- unsigned long cpumsr;
+ unsigned long cpumsr __maybe_unused;
WARN_ON(preemptible());
@@ -293,7 +293,7 @@ EXPORT_SYMBOL(giveup_altivec);
void enable_kernel_altivec(void)
{
- unsigned long cpumsr;
+ unsigned long cpumsr __maybe_unused;
WARN_ON(preemptible());
--
2.11.0
On 11/07/2018 08:26 PM, Mathieu Malaterre wrote:
> Add gcc attribute unused for `cpumsr` variable.
>
> Fix warnings treated as errors with W=1:
>
> arch/powerpc/kernel/process.c:231:16: error: variable ‘cpumsr’ set but not used [-Werror=unused-but-set-variable]
> arch/powerpc/kernel/process.c:296:16: error: variable ‘cpumsr’ set but not used [-Werror=unused-but-set-variable]
>
> Signed-off-by: Mathieu Malaterre <[email protected]>
I don't think this is the good way to fix that. This problem was
introduced by commit 5c784c8414fb ("powerpc/tm: Remove
msr_tm_active()"). That commit should be reverted and fixed.
That commit should have removed the macro and kept the inline function.
Christophe
> ---
> arch/powerpc/kernel/process.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 96f34730010f..b9f1a2408738 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -228,7 +228,7 @@ EXPORT_SYMBOL_GPL(flush_fp_to_thread);
>
> void enable_kernel_fp(void)
> {
> - unsigned long cpumsr;
> + unsigned long cpumsr __maybe_unused;
>
> WARN_ON(preemptible());
>
> @@ -293,7 +293,7 @@ EXPORT_SYMBOL(giveup_altivec);
>
> void enable_kernel_altivec(void)
> {
> - unsigned long cpumsr;
> + unsigned long cpumsr __maybe_unused;
>
> WARN_ON(preemptible());
>
>
On Thu, Nov 8, 2018 at 7:09 AM Christophe Leroy <[email protected]> wrote:
>
>
>
> On 11/07/2018 08:26 PM, Mathieu Malaterre wrote:
> > Add gcc attribute unused for `cpumsr` variable.
> >
> > Fix warnings treated as errors with W=1:
> >
> > arch/powerpc/kernel/process.c:231:16: error: variable ‘cpumsr’ set but not used [-Werror=unused-but-set-variable]
> > arch/powerpc/kernel/process.c:296:16: error: variable ‘cpumsr’ set but not used [-Werror=unused-but-set-variable]
> >
> > Signed-off-by: Mathieu Malaterre <[email protected]>
>
> I don't think this is the good way to fix that. This problem was
> introduced by commit 5c784c8414fb ("powerpc/tm: Remove
> msr_tm_active()"). That commit should be reverted and fixed.
I see, it makes sense.
> That commit should have removed the macro and kept the inline function.
Breno, what do you think ?
> Christophe
>
> > ---
> > arch/powerpc/kernel/process.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> > index 96f34730010f..b9f1a2408738 100644
> > --- a/arch/powerpc/kernel/process.c
> > +++ b/arch/powerpc/kernel/process.c
> > @@ -228,7 +228,7 @@ EXPORT_SYMBOL_GPL(flush_fp_to_thread);
> >
> > void enable_kernel_fp(void)
> > {
> > - unsigned long cpumsr;
> > + unsigned long cpumsr __maybe_unused;
> >
> > WARN_ON(preemptible());
> >
> > @@ -293,7 +293,7 @@ EXPORT_SYMBOL(giveup_altivec);
> >
> > void enable_kernel_altivec(void)
> > {
> > - unsigned long cpumsr;
> > + unsigned long cpumsr __maybe_unused;
> >
> > WARN_ON(preemptible());
> >
> >
Hi Mathieu, Christophe
Thanks for spotting and fixing this bug.
On 11/08/2018 05:25 AM, Mathieu Malaterre wrote:
> On Thu, Nov 8, 2018 at 7:09 AM Christophe Leroy <[email protected]> wrote:
>>
>>
>>
>> On 11/07/2018 08:26 PM, Mathieu Malaterre wrote:
>>> Add gcc attribute unused for `cpumsr` variable.
>>>
>>> Fix warnings treated as errors with W=1:
>>>
>>> arch/powerpc/kernel/process.c:231:16: error: variable ‘cpumsr’ set but not used [-Werror=unused-but-set-variable]
>>> arch/powerpc/kernel/process.c:296:16: error: variable ‘cpumsr’ set but not used [-Werror=unused-but-set-variable]
>>>
>>> Signed-off-by: Mathieu Malaterre <[email protected]>
>>
>> I don't think this is the good way to fix that. This problem was
>> introduced by commit 5c784c8414fb ("powerpc/tm: Remove
>> msr_tm_active()"). That commit should be reverted and fixed.
>
> I see, it makes sense.
>
>> That commit should have removed the macro and kept the inline function.
>
> Breno, what do you think ?
Turning this macro into a function might cause the code to be more confused,
since all the other TM states bits are checked using a macro, for example:
MSR_TM_SUSPENDED Checks if the MSR has Suspended bits set
MSR_TM_TRANSACTIONAL Checks if the MSR has the transactional bits set
MSR_TM_RESV Checks if the MSR has the TM reserved bits set
That said, I understand that it makes sense to have an uniform way to check
for TM bits in MSR, thus having a MSR_TM_ACTIVE macro to check for the active
bits. Using a non-uniform function just to fix this warning seems to be an
overkill. Reverting the patch seems to bring back the old style, which is
having a macro and a function with the same name, where the function just
calls the macro.
Anyway, I think it might have other ways to fix warning, as I can think now:
1) Avoid setting cpumsr if CONFIG_PPC_TRANSACTIONAL_MEM is not enabled
2) If !CONFIG_PPC_TRANSACTIONAL_MEM, redefine MSR_TM_ACTIVE(x) to something
as (x & 0) instead of 0.
3) Avoid double definition of MSR_TM_ACTIVE, i.e, have the same definition
independent of PPC_TRANSACTIONAL_MEM being set or not.
Anyway, I would like to try option 3), which is the hardest one to implement
and validate, but it seems to be the most correct option, once it checks for
a MSR bit configuration, and the caller should have the logic.