Messages in this thread | | | Date | Wed, 22 Oct 2014 11:47:42 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH 1/2] ARM: perf: armv7 remove useless return and check of idx in counter handling |
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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 <chaiw.fnst@cn.fujitsu.com>
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 <mark.rutland@arm.com>
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 >
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