From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932767AbaJVKst (ORCPT ); Wed, 22 Oct 2014 06:48:49 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:37404 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932450AbaJVKss (ORCPT ); Wed, 22 Oct 2014 06:48:48 -0400 Date: Wed, 22 Oct 2014 11:47:42 +0100 From: Mark Rutland To: chai wen Cc: Will Deacon , "linux@arm.linux.org.uk" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "yuichi.kusakabe@jp.fujitsu.com" , Sudeep Holla Subject: Re: [PATCH 1/2] ARM: perf: armv7 remove useless return and check of idx in counter handling Message-ID: <20141022104742.GD22642@leverpostej> References: <1413966107-11881-1-git-send-email-chaiw.fnst@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1413966107-11881-1-git-send-email-chaiw.fnst@cn.fujitsu.com> Thread-Topic: [PATCH 1/2] ARM: perf: armv7 remove useless return and check of idx in counter handling Accept-Language: en-GB, en-US Content-Language: en-US User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wed, Oct 22, 2014 at 09:21:46AM +0100, chai wen wrote: > Idx sanity check was once implemented separately in these counter handling > functions and then return value was treated as a judgement. > armv7_pmnc_select_counter() > armv7_pmnc_enable_counter() > armv7_pmnc_disable_counter() > armv7_pmnc_enable_intens() > armv7_pmnc_disable_intens() > But we do not need to do this now, and the return of idx is useless. > > Signed-off-by: chai wen It looks like the validation was moved out of all of these functions in 7279adbd9bb8ef8f (ARM: perf: check ARMv7 counter validity on a per-pmu basis), and we just missed the opportunity to simplify callers at the time. It would be nice if we mentioned that in the commit message -- it takes a while to figure out and it's handy for reference. > --- > arch/arm/kernel/perf_event_v7.c | 32 ++++++++++++++------------------ > 1 files changed, 14 insertions(+), 18 deletions(-) > > diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c > index 116758b..f66a9b8 100644 > --- a/arch/arm/kernel/perf_event_v7.c > +++ b/arch/arm/kernel/perf_event_v7.c > @@ -564,13 +564,11 @@ static inline int armv7_pmnc_counter_has_overflowed(u32 pmnc, int idx) > return pmnc & BIT(ARMV7_IDX_TO_COUNTER(idx)); > } > > -static inline int armv7_pmnc_select_counter(int idx) > +static inline void armv7_pmnc_select_counter(int idx) > { > u32 counter = ARMV7_IDX_TO_COUNTER(idx); > asm volatile("mcr p15, 0, %0, c9, c12, 5" : : "r" (counter)); > isb(); > - > - return idx; > } > > static inline u32 armv7pmu_read_counter(struct perf_event *event) > @@ -585,8 +583,10 @@ static inline u32 armv7pmu_read_counter(struct perf_event *event) > smp_processor_id(), idx); > else if (idx == ARMV7_IDX_CYCLE_COUNTER) > asm volatile("mrc p15, 0, %0, c9, c13, 0" : "=r" (value)); > - else if (armv7_pmnc_select_counter(idx) == idx) > + else { > + armv7_pmnc_select_counter(idx); > asm volatile("mrc p15, 0, %0, c9, c13, 2" : "=r" (value)); > + } Please make the braces consistent -- if one branch in an if .. else chain needs them, they all do (see Documentation/CodingStyle). > > return value; > } > @@ -602,40 +602,38 @@ static inline void armv7pmu_write_counter(struct perf_event *event, u32 value) > smp_processor_id(), idx); > else if (idx == ARMV7_IDX_CYCLE_COUNTER) > asm volatile("mcr p15, 0, %0, c9, c13, 0" : : "r" (value)); > - else if (armv7_pmnc_select_counter(idx) == idx) > + else { > + armv7_pmnc_select_counter(idx); > asm volatile("mcr p15, 0, %0, c9, c13, 2" : : "r" (value)); > + } Likewise here. Otherwise this looks like a nice cleanup to me, so with those changes: Acked-by: Mark Rutland Thanks, Mark. > } > > static inline void armv7_pmnc_write_evtsel(int idx, u32 val) > { > - if (armv7_pmnc_select_counter(idx) == idx) { > - val &= ARMV7_EVTYPE_MASK; > - asm volatile("mcr p15, 0, %0, c9, c13, 1" : : "r" (val)); > - } > + armv7_pmnc_select_counter(idx); > + val &= ARMV7_EVTYPE_MASK; > + asm volatile("mcr p15, 0, %0, c9, c13, 1" : : "r" (val)); > } > > -static inline int armv7_pmnc_enable_counter(int idx) > +static inline void armv7_pmnc_enable_counter(int idx) > { > u32 counter = ARMV7_IDX_TO_COUNTER(idx); > asm volatile("mcr p15, 0, %0, c9, c12, 1" : : "r" (BIT(counter))); > - return idx; > } > > -static inline int armv7_pmnc_disable_counter(int idx) > +static inline void armv7_pmnc_disable_counter(int idx) > { > u32 counter = ARMV7_IDX_TO_COUNTER(idx); > asm volatile("mcr p15, 0, %0, c9, c12, 2" : : "r" (BIT(counter))); > - return idx; > } > > -static inline int armv7_pmnc_enable_intens(int idx) > +static inline void armv7_pmnc_enable_intens(int idx) > { > u32 counter = ARMV7_IDX_TO_COUNTER(idx); > asm volatile("mcr p15, 0, %0, c9, c14, 1" : : "r" (BIT(counter))); > - return idx; > } > > -static inline int armv7_pmnc_disable_intens(int idx) > +static inline void armv7_pmnc_disable_intens(int idx) > { > u32 counter = ARMV7_IDX_TO_COUNTER(idx); > asm volatile("mcr p15, 0, %0, c9, c14, 2" : : "r" (BIT(counter))); > @@ -643,8 +641,6 @@ static inline int armv7_pmnc_disable_intens(int idx) > /* Clear the overflow flag in case an interrupt is pending. */ > asm volatile("mcr p15, 0, %0, c9, c12, 3" : : "r" (BIT(counter))); > isb(); > - > - return idx; > } > > static inline u32 armv7_pmnc_getreset_flags(void) > -- > 1.7.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >