1. Patchew
  2. linux
  3. View series

[PATCHv2] powerpc: mm: radix_tlb: rearrange the if-else block

Anders Roxell posted 1 patch 4 years, 5 months ago
There is a newer version of this series
arch/powerpc/mm/book3s64/radix_tlb.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
[PATCHv2] powerpc: mm: radix_tlb: rearrange the if-else block
Posted by Anders Roxell 4 years, 5 months ago 
Clang warns:

arch/powerpc/mm/book3s64/radix_tlb.c:1191:23: error: variable 'hstart' is uninitialized when used here [-Werror,-Wuninitialized]
                                __tlbiel_va_range(hstart, hend, pid,
                                                  ^~~~~~
arch/powerpc/mm/book3s64/radix_tlb.c:1175:23: note: initialize the variable 'hstart' to silence this warning
                unsigned long hstart, hend;
                                    ^
                                     = 0
arch/powerpc/mm/book3s64/radix_tlb.c:1191:31: error: variable 'hend' is uninitialized when used here [-Werror,-Wuninitialized]
                                __tlbiel_va_range(hstart, hend, pid,
                                                          ^~~~
arch/powerpc/mm/book3s64/radix_tlb.c:1175:29: note: initialize the variable 'hend' to silence this warning
                unsigned long hstart, hend;
                                          ^
                                           = 0
2 errors generated.

Rework the 'if (IS_ENABLE(CONFIG_TRANSPARENT_HUGEPAGE))' so hstart/hend
always gets initialized, this will silence the warnings. That will also
simplify the 'else' path. Clang is getting confused with these warnings,
but the warnings is a false-positive.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 arch/powerpc/mm/book3s64/radix_tlb.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
index 7724af19ed7e..7d65965a0688 100644
--- a/arch/powerpc/mm/book3s64/radix_tlb.c
+++ b/arch/powerpc/mm/book3s64/radix_tlb.c
@@ -1174,12 +1174,9 @@ static inline void __radix__flush_tlb_range(struct mm_struct *mm,
 		bool hflush = false;
 		unsigned long hstart, hend;
 
-		if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
-			hstart = (start + PMD_SIZE - 1) & PMD_MASK;
-			hend = end & PMD_MASK;
-			if (hstart < hend)
-				hflush = true;
-		}
+		hstart = (start + PMD_SIZE - 1) & PMD_MASK;
+		hend = end & PMD_MASK;
+		hflush = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hstart < hend;
 
 		if (type == FLUSH_TYPE_LOCAL) {
 			asm volatile("ptesync": : :"memory");
-- 
2.34.1
Re: [PATCHv2] powerpc: mm: radix_tlb: rearrange the if-else block
Posted by Christophe Leroy 4 years, 5 months ago 

Le 28/01/2022 à 11:08, Anders Roxell a écrit :
> Clang warns:
> 
> arch/powerpc/mm/book3s64/radix_tlb.c:1191:23: error: variable 'hstart' is uninitialized when used here [-Werror,-Wuninitialized]
>                                  __tlbiel_va_range(hstart, hend, pid,
>                                                    ^~~~~~
> arch/powerpc/mm/book3s64/radix_tlb.c:1175:23: note: initialize the variable 'hstart' to silence this warning
>                  unsigned long hstart, hend;
>                                      ^
>                                       = 0
> arch/powerpc/mm/book3s64/radix_tlb.c:1191:31: error: variable 'hend' is uninitialized when used here [-Werror,-Wuninitialized]
>                                  __tlbiel_va_range(hstart, hend, pid,
>                                                            ^~~~
> arch/powerpc/mm/book3s64/radix_tlb.c:1175:29: note: initialize the variable 'hend' to silence this warning
>                  unsigned long hstart, hend;
>                                            ^
>                                             = 0
> 2 errors generated.
> 
> Rework the 'if (IS_ENABLE(CONFIG_TRANSPARENT_HUGEPAGE))' so hstart/hend
> always gets initialized, this will silence the warnings. That will also
> simplify the 'else' path. Clang is getting confused with these warnings,
> but the warnings is a false-positive.
> 
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Suggested-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> ---
>   arch/powerpc/mm/book3s64/radix_tlb.c | 9 +++------
>   1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
> index 7724af19ed7e..7d65965a0688 100644
> --- a/arch/powerpc/mm/book3s64/radix_tlb.c
> +++ b/arch/powerpc/mm/book3s64/radix_tlb.c
> @@ -1174,12 +1174,9 @@ static inline void __radix__flush_tlb_range(struct mm_struct *mm,
>   		bool hflush = false;

You should then remove the default initialisation of hflush to false 
which has become pointless.

With that fixed,

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>


>   		unsigned long hstart, hend;
>   
> -		if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
> -			hstart = (start + PMD_SIZE - 1) & PMD_MASK;
> -			hend = end & PMD_MASK;
> -			if (hstart < hend)
> -				hflush = true;
> -		}
> +		hstart = (start + PMD_SIZE - 1) & PMD_MASK;
> +		hend = end & PMD_MASK;
> +		hflush = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hstart < hend;
>   
>   		if (type == FLUSH_TYPE_LOCAL) {
>   			asm volatile("ptesync": : :"memory");
Re: [PATCHv2] powerpc: mm: radix_tlb: rearrange the if-else block
Posted by Anders Roxell 4 years, 5 months ago 
On Fri, 28 Jan 2022 at 11:14, Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
>
>
>
> Le 28/01/2022 à 11:08, Anders Roxell a écrit :
> > Clang warns:
> >
> > arch/powerpc/mm/book3s64/radix_tlb.c:1191:23: error: variable 'hstart' is uninitialized when used here [-Werror,-Wuninitialized]
> >                                  __tlbiel_va_range(hstart, hend, pid,
> >                                                    ^~~~~~
> > arch/powerpc/mm/book3s64/radix_tlb.c:1175:23: note: initialize the variable 'hstart' to silence this warning
> >                  unsigned long hstart, hend;
> >                                      ^
> >                                       = 0
> > arch/powerpc/mm/book3s64/radix_tlb.c:1191:31: error: variable 'hend' is uninitialized when used here [-Werror,-Wuninitialized]
> >                                  __tlbiel_va_range(hstart, hend, pid,
> >                                                            ^~~~
> > arch/powerpc/mm/book3s64/radix_tlb.c:1175:29: note: initialize the variable 'hend' to silence this warning
> >                  unsigned long hstart, hend;
> >                                            ^
> >                                             = 0
> > 2 errors generated.
> >
> > Rework the 'if (IS_ENABLE(CONFIG_TRANSPARENT_HUGEPAGE))' so hstart/hend
> > always gets initialized, this will silence the warnings. That will also
> > simplify the 'else' path. Clang is getting confused with these warnings,
> > but the warnings is a false-positive.
> >
> > Suggested-by: Arnd Bergmann <arnd@arndb.de>
> > Suggested-by: Nathan Chancellor <nathan@kernel.org>
> > Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> > ---
> >   arch/powerpc/mm/book3s64/radix_tlb.c | 9 +++------
> >   1 file changed, 3 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
> > index 7724af19ed7e..7d65965a0688 100644
> > --- a/arch/powerpc/mm/book3s64/radix_tlb.c
> > +++ b/arch/powerpc/mm/book3s64/radix_tlb.c
> > @@ -1174,12 +1174,9 @@ static inline void __radix__flush_tlb_range(struct mm_struct *mm,
> >               bool hflush = false;
>
> You should then remove the default initialisation of hflush to false
> which has become pointless.
>
> With that fixed,
>
> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>

Thank you for the review.
I will send a v3 shortly with that fixed.

Cheers,
Anders

Patchew 2.1-devel-ea86937

© 2016 - 2026 Red Hat, Inc.