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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc:     christophe.leroy@c-s.fr, mikey@neuling.org, apopple@linux.ibm.com,
        linux-kernel@vger.kernel.org, npiggin@gmail.com, paulus@samba.org,
        naveen.n.rao@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] hw_breakpoint: Fix build warnings with clang
In-Reply-To: <0217bbaf-a831-8aea-3ecd-fa217fca1669@csgroup.eu>
References: <20200602041208.128913-1-ravi.bangoria@linux.ibm.com> <0217bbaf-a831-8aea-3ecd-fa217fca1669@csgroup.eu>
Date:   Tue, 02 Jun 2020 21:00:39 +1000
Message-ID: <87d06hivfs.fsf@mpe.ellerman.id.au>
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Sender: linux-kernel-owner@vger.kernel.org
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Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Le 02/06/2020 =C3=A0 06:12, Ravi Bangoria a =C3=A9crit=C2=A0:
>> kbuild test robot reported few build warnings with hw_breakpoint code
>> when compiled with clang[1]. Fix those.
>>=20
>> [1]: https://lore.kernel.org/linuxppc-dev/202005192233.oi9CjRtA%25lkp@in=
tel.com/
>>=20

This should have mentioned that some of the errors were recently
introduced by your commit.

>> Reported-by: kbuild test robot <lkp@intel.com>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>> ---
>> Note: Prepared on top of powerpc/next.
>>=20
>>   arch/powerpc/include/asm/hw_breakpoint.h | 3 ---
>>   include/linux/hw_breakpoint.h            | 4 ++++
>>   2 files changed, 4 insertions(+), 3 deletions(-)
>>=20
>> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/inc=
lude/asm/hw_breakpoint.h
>> index f42a55eb77d2..cb424799da0d 100644
>> --- a/arch/powerpc/include/asm/hw_breakpoint.h
>> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
>> @@ -70,9 +70,6 @@ extern int hw_breakpoint_exceptions_notify(struct noti=
fier_block *unused,
>>   						unsigned long val, void *data);
>>   int arch_install_hw_breakpoint(struct perf_event *bp);
>>   void arch_uninstall_hw_breakpoint(struct perf_event *bp);
>> -int arch_reserve_bp_slot(struct perf_event *bp);
>> -void arch_release_bp_slot(struct perf_event *bp);
>> -void arch_unregister_hw_breakpoint(struct perf_event *bp);
>>   void hw_breakpoint_pmu_read(struct perf_event *bp);
>>   extern void flush_ptrace_hw_breakpoint(struct task_struct *tsk);
>>=20=20=20
>> diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint=
.h
>> index 6058c3844a76..521481f0d320 100644
>> --- a/include/linux/hw_breakpoint.h
>> +++ b/include/linux/hw_breakpoint.h
>> @@ -80,6 +80,10 @@ extern int dbg_reserve_bp_slot(struct perf_event *bp);
>>   extern int dbg_release_bp_slot(struct perf_event *bp);
>>   extern int reserve_bp_slot(struct perf_event *bp);
>>   extern void release_bp_slot(struct perf_event *bp);
>> +extern int hw_breakpoint_weight(struct perf_event *bp);
>> +extern int arch_reserve_bp_slot(struct perf_event *bp);
>> +extern void arch_release_bp_slot(struct perf_event *bp);
>> +extern void arch_unregister_hw_breakpoint(struct perf_event *bp);
>
> Please no new 'extern'. In the old days 'extern' keyword was used, but=20
> new code shall not introduce new unnecessary usage of 'extern' keyword.=20
> See report from Checkpatch below:
>
> WARNING:COMMIT_LOG_LONG_LINE: Possible unwrapped commit description=20
> (prefer a maximum 75 chars per line)
> #9:
> [1]:=20
> https://lore.kernel.org/linuxppc-dev/202005192233.oi9CjRtA%25lkp@intel.co=
m/
>
> CHECK:AVOID_EXTERNS: extern prototypes should be avoided in .h files
> #40: FILE: include/linux/hw_breakpoint.h:83:
> +extern int hw_breakpoint_weight(struct perf_event *bp);

I fixed it up when applying.

cheers