From: Cristian Marussi <cristian.marussi@arm.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-arch@vger.kernel.org, mark.rutland@arm.com,
peterz@infradead.org, catalin.marinas@arm.com,
linux-kernel@vger.kernel.org, takahiro.akashi@linaro.org,
james.morse@arm.com, hidehiro.kawai.ez@hitachi.com,
tglx@linutronix.de, will@kernel.org, dave.martin@arm.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH 5/7] arm64: smp: use generic SMP stop common code
Date: Mon, 26 Aug 2019 20:58:01 +0100 [thread overview]
Message-ID: <c6a86709-6faf-bf84-08aa-c41dab61c58f@arm.com> (raw)
In-Reply-To: <20190826153236.GA9591@infradead.org>
Hi
On 8/26/19 4:32 PM, Christoph Hellwig wrote:
>> +config ARCH_USE_COMMON_SMP_STOP
>> + def_bool y if SMP
>
> The option belongs into common code and the arch code shoud only
> select it.
>
In fact that was my first approach, but then I noticed that in kernel/ topdir
there was no generic Kconfig but only subsystem specific ones:
Kconfig.freezer Kconfig.hz Kconfig.locks Kconfig.preempt
while instead looking into archs top level Kconfig, beside the usual arch/Kconfig selects,
I could find this similar sort of "reversed" approach in which the arch defined and
selected a CONFIG which was indeed then used only in common code like in:
20:37 $ egrep -R ARCH_HAS_CACHE_LINE_SIZE .
./arch/arc/Kconfig:config ARCH_HAS_CACHE_LINE_SIZE
./arch/x86/Kconfig:config ARCH_HAS_CACHE_LINE_SIZE
./arch/arm64/Kconfig:config ARCH_HAS_CACHE_LINE_SIZE
./include/linux/cache.h:#ifndef CONFIG_ARCH_HAS_CACHE_LINE_SIZE
20:39 $ egrep -R ARCH_HAS_KEXEC_PURGATORY .
./arch/powerpc/Kconfig:config ARCH_HAS_KEXEC_PURGATORY
./arch/x86/Kconfig:config ARCH_HAS_KEXEC_PURGATORY
./arch/s390/Kconfig:config ARCH_HAS_KEXEC_PURGATORY
./arch/s390/purgatory/Makefile:obj-$(CONFIG_ARCH_HAS_KEXEC_PURGATORY) += kexec-purgatory.o
./arch/s390/Kbuild:obj-$(CONFIG_ARCH_HAS_KEXEC_PURGATORY) += purgatory/
./kernel/kexec_file.c: if (!IS_ENABLED(CONFIG_ARCH_HAS_KEXEC_PURGATORY))
so I thought it was an acceptable option and I went for it, not to introduce a new kernel/Kconfig.smp
just for this new config option; but in fact I could have missed the real reason underlying these two
different choices.
Thanks
Cristian
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next prev parent reply other threads:[~2019-08-26 19:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-23 11:57 [RFC PATCH 0/7] Unify SMP stop generic logic to common code Cristian Marussi
2019-08-23 11:57 ` [RFC PATCH 1/7] smp: add generic SMP-stop support " Cristian Marussi
2019-08-23 11:57 ` [RFC PATCH 2/7] smp: unify crash_ and smp_send_stop() logic Cristian Marussi
2019-08-23 11:57 ` [RFC PATCH 3/7] smp: coordinate concurrent crash/smp stop calls Cristian Marussi
2019-08-23 11:57 ` [RFC PATCH 4/7] smp: address races of starting CPUs while stopping Cristian Marussi
2019-08-23 11:57 ` [RFC PATCH 5/7] arm64: smp: use generic SMP stop common code Cristian Marussi
2019-08-26 15:32 ` Christoph Hellwig
2019-08-26 19:58 ` Cristian Marussi [this message]
2019-08-26 22:26 ` Thomas Gleixner
2019-08-27 14:34 ` Cristian Marussi
2019-08-23 11:57 ` [RFC PATCH 6/7] arm64: smp: use SMP crash-stop " Cristian Marussi
2019-08-23 11:57 ` [RFC PATCH 7/7] arm64: smp: add arch specific cpu parking helper Cristian Marussi
2019-08-26 15:34 ` [RFC PATCH 0/7] Unify SMP stop generic logic to common code Christoph Hellwig
2019-08-26 19:33 ` Cristian Marussi
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