From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: Michael Kelley <mikelley@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
KY Srinivasan <kys@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>, "hpa@zytor.com" <hpa@zytor.com>,
"arnd@arndb.de" <arnd@arndb.de>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Subject: Re: [PATCH v2 07/10] clocksource/drivers/hyper-v: Handle vDSO differences inline
Date: Tue, 2 Mar 2021 14:01:24 +0100 [thread overview]
Message-ID: <f09da965-aeda-7edf-722c-dbc9d7daab38@linaro.org> (raw)
In-Reply-To: <MWHPR21MB15930DD833E49415610C021DD7999@MWHPR21MB1593.namprd21.prod.outlook.com>
On 02/03/2021 02:29, Michael Kelley wrote:
> From: Daniel Lezcano <daniel.lezcano@linaro.org> Sent: Monday, March 1, 2021 4:22 AM
>>
>> On 01/03/2021 02:15, Michael Kelley wrote:
>>> While the driver for the Hyper-V Reference TSC and STIMERs is architecture
>>> neutral, vDSO is implemented for x86/x64, but not for ARM64. Current code
>>> calls into utility functions under arch/x86 (and coming, under arch/arm64)
>>> to handle the difference.
>>>
>>> Change this approach to handle the difference inline based on whether
>>> VDSO_CLOCK_MODE_HVCLOCK is present. The new approach removes code under
>>> arch/* since the difference is tied more to the specifics of the Linux
>>> implementation than to the architecture.
>>>
>>> No functional change.
>>
>> A suggestion below
>>
>>
>>> Signed-off-by: Michael Kelley <mikelley@microsoft.com>
>>> Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
>>> ---
>>> arch/x86/include/asm/mshyperv.h | 4 ----
>>> drivers/clocksource/hyperv_timer.c | 10 ++++++++--
>>> 2 files changed, 8 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
>>> index c73c127..5e5e08aa 100644
>>> --- a/drivers/clocksource/hyperv_timer.c
>>> +++ b/drivers/clocksource/hyperv_timer.c
>>> @@ -372,7 +372,9 @@ static void resume_hv_clock_tsc(struct clocksource *arg)
>>>
>>> static int hv_cs_enable(struct clocksource *cs)
>>
>> static __maybe_unused int hv_cs_enable(struct clocksource *cs)
>>
>>> {
>>> - hv_enable_vdso_clocksource();
>>> +#ifdef VDSO_CLOCKMODE_HVCLOCK
>>> + vclocks_set_used(VDSO_CLOCKMODE_HVCLOCK);
>>> +#endif
>>> return 0;
>>> }
>>>
>>> @@ -385,6 +387,11 @@ static int hv_cs_enable(struct clocksource *cs)
>>> .suspend= suspend_hv_clock_tsc,
>>> .resume = resume_hv_clock_tsc,
>>> .enable = hv_cs_enable,
>>> +#ifdef VDSO_CLOCKMODE_HVCLOCK
>>> + .vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK,
>>> +#else
>>> + .vdso_clock_mode = VDSO_CLOCKMODE_NONE,
>>> +#endif
>>
>> #ifdef VDSO_CLOCKMODE_HVCLOCK
>> .enable = hv_cs_enable,
>> .vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK,
>> #else
>> .vdso_clock_mode = VDSO_CLOCKMODE_NONE,
>> #endif
>>
>
> Is there any particular benefit (that I might not be recognizing)
> to having the .enable function be NULL vs. a function that
> does nothing? I can see the handful of places where the
> .enable function is invoked, and there doesn't seem to be
> much difference.
>
> In any case, I have no problem with making the change in
> a v3 of the patch set.
It is just coding style, it allows to remove a #ifdef in the code.
--
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next prev parent reply other threads:[~2021-03-03 5:38 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-01 1:15 [PATCH v2 00/10] Refactor arch specific Hyper-V code Michael Kelley
2021-03-01 1:15 ` [PATCH v2 01/10] Drivers: hv: vmbus: Move Hyper-V page allocator to arch neutral code Michael Kelley
2021-03-02 12:57 ` ** POTENTIAL FRAUD ALERT - RED HAT ** " Vitaly Kuznetsov
2021-03-02 17:42 ` Michael Kelley
2021-03-01 1:15 ` [PATCH v2 02/10] x86/hyper-v: Move hv_message_type to architecture neutral module Michael Kelley
2021-03-01 1:15 ` [PATCH v2 03/10] Drivers: hv: Redo Hyper-V synthetic MSR get/set functions Michael Kelley
2021-03-01 1:15 ` [PATCH v2 04/10] Drivers: hv: vmbus: Move hyperv_report_panic_msg to arch neutral code Michael Kelley
2021-03-01 1:15 ` [PATCH v2 05/10] Drivers: hv: vmbus: Handle auto EOI quirk inline Michael Kelley
2021-03-01 1:15 ` [PATCH v2 06/10] Drivers: hv: vmbus: Move handling of VMbus interrupts Michael Kelley
2021-03-01 1:15 ` [PATCH v2 07/10] clocksource/drivers/hyper-v: Handle vDSO differences inline Michael Kelley
2021-03-01 12:21 ` Daniel Lezcano
2021-03-02 1:29 ` Michael Kelley
2021-03-02 13:01 ` Daniel Lezcano [this message]
2021-03-01 1:15 ` [PATCH v2 08/10] clocksource/drivers/hyper-v: Handle sched_clock " Michael Kelley
2021-03-01 14:25 ` Daniel Lezcano
2021-03-02 1:38 ` Michael Kelley
2021-03-02 13:34 ` Daniel Lezcano
2021-03-01 1:15 ` [PATCH v2 09/10] clocksource/drivers/hyper-v: Set clocksource rating based on Hyper-V feature Michael Kelley
2021-03-01 15:42 ` Daniel Lezcano
2021-03-01 1:15 ` [PATCH v2 10/10] clocksource/drivers/hyper-v: Move handling of STIMER0 interrupts Michael Kelley
2021-03-01 18:44 ` Daniel Lezcano
2021-03-02 1:40 ` Michael Kelley
2021-03-01 11:30 ` [PATCH v2 00/10] Refactor arch specific Hyper-V code Wei Liu
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