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From: Mark Rutland <mark.rutland@arm.com>
To: Joe Perches <joe@perches.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Zhu Lingshan <lingshan.zhu@intel.com>,
	wanpengli@tencent.com, Like Xu <like.xu@linux.intel.com>,
	eranian@google.com, weijiang.yang@intel.com,
	Guo Ren <guoren@kernel.org>,
	linux-riscv@lists.infradead.org, Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu, kan.liang@linux.intel.com,
	ak@linux.intel.com, kvm@vger.kernel.org,
	Marc Zyngier <maz@kernel.org>,
	joro@8bytes.org, x86@kernel.org, linux-csky@vger.kernel.org,
	wei.w.wang@intel.com, xen-devel@lists.xenproject.org,
	liuxiangdong5@huawei.com, bp@alien8.de,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	linux-arm-kernel@lists.infradead.org, jmattson@google.com,
	like.xu.linux@gmail.com, Nick Hu <nickhu@andestech.com>,
	seanjc@google.com, linux-kernel@vger.kernel.org,
	pbonzini@redhat.com, vkuznets@redhat.com
Subject: Re: [PATCH V7 01/18] perf/core: Use static_call to optimize perf_guest_info_callbacks
Date: Fri, 2 Jul 2021 17:38:36 +0100	[thread overview]
Message-ID: <20210702163836.GB94260@C02TD0UTHF1T.local> (raw)
In-Reply-To: <7379289718c6826dd1affec5824b749be2aee0a4.camel@perches.com>

On Fri, Jul 02, 2021 at 09:00:22AM -0700, Joe Perches wrote:
> On Fri, 2021-07-02 at 13:22 +0200, Peter Zijlstra wrote:
> > On Tue, Jun 22, 2021 at 05:42:49PM +0800, Zhu Lingshan wrote:
> > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> []
> > > @@ -90,6 +90,27 @@ DEFINE_STATIC_CALL_NULL(x86_pmu_pebs_aliases, *x86_pmu.pebs_aliases);
> > >   */
> > >  DEFINE_STATIC_CALL_RET0(x86_pmu_guest_get_msrs, *x86_pmu.guest_get_msrs);
> > >  
> > > 
> > > +DEFINE_STATIC_CALL_RET0(x86_guest_state, *(perf_guest_cbs->state));
> > > +DEFINE_STATIC_CALL_RET0(x86_guest_get_ip, *(perf_guest_cbs->get_ip));
> > > +DEFINE_STATIC_CALL_RET0(x86_guest_handle_intel_pt_intr, *(perf_guest_cbs->handle_intel_pt_intr));
> > > +
> > > +void arch_perf_update_guest_cbs(void)
> > > +{
> > > +	static_call_update(x86_guest_state, (void *)&__static_call_return0);
> > > +	static_call_update(x86_guest_get_ip, (void *)&__static_call_return0);
> > > +	static_call_update(x86_guest_handle_intel_pt_intr, (void *)&__static_call_return0);
> > > +
> > > +	if (perf_guest_cbs && perf_guest_cbs->state)
> > > +		static_call_update(x86_guest_state, perf_guest_cbs->state);
> > > +
> > > +	if (perf_guest_cbs && perf_guest_cbs->get_ip)
> > > +		static_call_update(x86_guest_get_ip, perf_guest_cbs->get_ip);
> > > +
> > > +	if (perf_guest_cbs && perf_guest_cbs->handle_intel_pt_intr)
> > > +		static_call_update(x86_guest_handle_intel_pt_intr,
> > > +				   perf_guest_cbs->handle_intel_pt_intr);
> > > +}
> > 
> > Coding style wants { } on that last if().
> 
> That's just your personal preference.
> 
> The coding-style document doesn't require that.
> 
> It just says single statement.  It's not the number of
> vertical lines or characters required for the statement.
> 
> ----------------------------------
> 
> Do not unnecessarily use braces where a single statement will do.
> 
> .. code-block:: c
> 
> 	if (condition)
> 		action();
> 
> and
> 
> .. code-block:: none
> 
> 	if (condition)
> 		do_this();
> 	else
> 		do_that();
> 
> This does not apply if only one branch of a conditional statement is a single
> statement; in the latter case use braces in both branches:

Immediately after this, we say:

| Also, use braces when a loop contains more than a single simple statement:
|
| .. code-block:: c
| 
|         while (condition) {
|                 if (test)
|                         do_something();
|         }
| 

... and while that says "a loop", the principle is obviously supposed to
apply to conditionals too; structurally they're no different. We should
just fix the documentation to say "a loop or conditional", or something
to that effect.

Mark.

  parent reply	other threads:[~2021-07-02 16:38 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-22  9:42 [PATCH V7 00/18] KVM: x86/pmu: Add *basic* support to enable guest PEBS via DS Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 01/18] perf/core: Use static_call to optimize perf_guest_info_callbacks Zhu Lingshan
2021-07-02 11:22   ` Peter Zijlstra
2021-07-02 16:00     ` Joe Perches
2021-07-02 16:19       ` Peter Zijlstra
2021-07-02 16:42         ` Joe Perches
2021-07-02 16:38       ` Mark Rutland [this message]
2021-07-02 16:56         ` Joe Perches
2021-07-08  8:53     ` Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 02/18] perf/x86/intel: Add EPT-Friendly PEBS for Ice Lake Server Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 03/18] perf/x86/intel: Handle guest PEBS overflow PMI for KVM guest Zhu Lingshan
2021-07-02 11:28   ` Peter Zijlstra
2021-07-08 13:39     ` Zhu, Lingshan
2021-06-22  9:42 ` [PATCH V7 04/18] perf/x86/core: Pass "struct kvm_pmu *" to determine the guest values Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 05/18] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE_EMON bit when vPMU is enabled Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 06/18] KVM: x86/pmu: Introduce the ctrl_mask value for fixed counter Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 07/18] x86/perf/core: Add pebs_capable to store valid PEBS_COUNTER_MASK value Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 08/18] KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 09/18] KVM: x86/pmu: Reprogram PEBS event to emulate guest PEBS counter Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 10/18] KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter Zhu Lingshan
2021-06-22  9:42 ` [PATCH V7 11/18] KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to support guest DS Zhu Lingshan
2021-07-02 11:52   ` Peter Zijlstra
2021-07-08  8:52     ` Zhu, Lingshan
2021-06-22  9:43 ` [PATCH V7 12/18] KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS Zhu Lingshan
2021-06-22  9:43 ` [PATCH V7 13/18] KVM: x86: Set PEBS_UNAVAIL in IA32_MISC_ENABLE when PEBS is enabled Zhu Lingshan
2021-06-22  9:43 ` [PATCH V7 14/18] KVM: x86/pmu: Move pmc_speculative_in_use() to arch/x86/kvm/pmu.h Zhu Lingshan
2021-06-22  9:43 ` [PATCH V7 15/18] KVM: x86/pmu: Disable guest PEBS temporarily in two rare situations Zhu Lingshan
2021-07-02 12:46   ` Peter Zijlstra
2021-07-08  8:52     ` Zhu, Lingshan
2021-06-22  9:43 ` [PATCH V7 16/18] KVM: x86/pmu: Add kvm_pmu_cap to optimize perf_get_x86_pmu_capability Zhu Lingshan
2021-06-22  9:43 ` [PATCH V7 17/18] KVM: x86/cpuid: Refactor host/guest CPU model consistency check Zhu Lingshan
2021-06-22  9:43 ` [PATCH V7 18/18] KVM: x86/pmu: Expose CPUIDs feature bits PDCM, DS, DTES64 Zhu Lingshan
2021-06-25  9:40 ` [PATCH V7 00/18] KVM: x86/pmu: Add *basic* support to enable guest PEBS via DS Liuxiangdong
2021-06-25  9:46   ` Zhu, Lingshan
2021-06-28  7:49     ` Wang, Wei W
2021-06-28  7:53       ` Zhu, Lingshan
2021-07-02 12:49 ` Peter Zijlstra
2021-07-12  1:37 ` Liuxiangdong
2021-07-12 10:34   ` Like Xu

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