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Message-ID: <cbcd29ab-2f8f-443e-96e4-0f2d134964db@arm.com>
Date: Mon, 6 May 2024 11:40:17 +0530
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Subject: Re: [PATCH v2 1/2] arm64/arch_timer: include <linux/percpu.h>
To: Puranjay Mohan <puranjay@kernel.org>,
 Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>,
 Sumit Garg <sumit.garg@linaro.org>, Stephen Boyd <swboyd@chromium.org>,
 Douglas Anderson <dianders@chromium.org>,
 "Peter Zijlstra (Intel)" <peterz@infradead.org>,
 Thomas Gleixner <tglx@linutronix.de>, Mark Rutland <mark.rutland@arm.com>,
 linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
 bpf@vger.kernel.org
References: <20240502123449.2690-1-puranjay@kernel.org>
 <7008cd0c-5b65-4289-9015-434cbe3d7e21@arm.com> <mb61p4jbf8c29.fsf@kernel.org>
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From: Anshuman Khandual <anshuman.khandual@arm.com>
In-Reply-To: <mb61p4jbf8c29.fsf@kernel.org>
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On 5/3/24 15:14, Puranjay Mohan wrote:
> Anshuman Khandual <anshuman.khandual@arm.com> writes:
> 
>> On 5/2/24 18:04, Puranjay Mohan wrote:
>>> arch_timer.h includes linux/smp.h to use DEFINE_PER_CPU() and it works
>>> because smp.h includes percpu.h. The next commit will remove percpu.h
>>> from smp.h and it will break this usage.
>>>
>>> Explicitly include percpu.h and remove smp.h
>>
>> But this particular change does not seem to be necessary for changing
>> raw_smp_processor_id() as current_thread_info()->cpu being done in the
>> later patch ? You might still leave header <asm/percpu.h> inclusion in
>> arch/arm64/include/asm/smp.h while dropping the per cpu cpu_number ?
> 
> commit 57c82954e77f ("arm64: make cpu number a percpu variable")
> created this percpu variable and included <asm/percpu.h> in <asm/smp.h>
> 
> Now we are removing the percpu variable cpu_number from smp.h, so there
> is no need to keep percpu.h in smp.h

Fair enough.

> 
> I feel users of DECLARE_PER_CPU_[...], etc. should include percpu.h and
> not smp.h as it makes reading the code more easier and can thwart build
> issues in the future, when headers are changed. 
Right, makes sense, hope there is no more such cases using smp.h to pull
in DECLARE_PER_CPU_[...]. A quick build on defconfig is successful after
this patch.