From: Nathan Chancellor <nathan@kernel.org>
To: Anders Roxell <anders.roxell@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
llvm@lists.linux.dev, ndesaulniers@google.com,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCHv3] powerpc: mm: radix_tlb: rearrange the if-else block
Date: Fri, 28 Jan 2022 08:02:58 -0700 [thread overview]
Message-ID: <YfQFom4xDcysN1yb@dev-arch.archlinux-ax161> (raw)
In-Reply-To: <20220128131713.299198-1-anders.roxell@linaro.org>
On Fri, Jan 28, 2022 at 02:17:13PM +0100, Anders Roxell wrote:
> 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>
> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> ---
> arch/powerpc/mm/book3s64/radix_tlb.c | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
> index 7724af19ed7e..5172d5cec2c0 100644
> --- a/arch/powerpc/mm/book3s64/radix_tlb.c
> +++ b/arch/powerpc/mm/book3s64/radix_tlb.c
> @@ -1171,15 +1171,12 @@ static inline void __radix__flush_tlb_range(struct mm_struct *mm,
> }
> }
> } else {
> - bool hflush = false;
> + bool hflush;
> 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
>
prev parent reply other threads:[~2022-01-28 15:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-28 13:17 [PATCHv3] powerpc: mm: radix_tlb: rearrange the if-else block Anders Roxell
2022-01-28 15:02 ` Nathan Chancellor [this message]
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