linux-kernel - Re: [PATCH] drivers/perf: riscv: Remove redundant macro check

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Message-ID: <20240709-unengaged-handgrip-56a5c7b3e1d1@spud>
Date: Tue, 9 Jul 2024 21:44:17 +0100
From: Conor Dooley <conor@...nel.org>
To: Charlie Jenkins <charlie@...osinc.com>
Cc: Xiao Wang <xiao.w.wang@...el.com>,
	Alexandre Ghiti <alexghiti@...osinc.com>, paul.walmsley@...ive.com,
	palmer@...belt.com, aou@...s.berkeley.edu, atishp@...shpatra.org,
	anup@...infault.org, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/perf: riscv: Remove redundant macro check

On Tue, Jul 09, 2024 at 01:29:42PM -0700, Charlie Jenkins wrote:
> On Mon, Jul 08, 2024 at 01:22:11PM +0100, Conor Dooley wrote:
> > On Mon, Jul 08, 2024 at 08:12:24PM +0800, Xiao Wang wrote:
> > > The macro CONFIG_RISCV_PMU must have been defined when riscv_pmu.c gets
> > > compiled, so this patch removes the redundant check.
> > 
> > Did you investigate why this define was added? Why do you think that it
> > is redundant, rather than checking the incorrect config option?
> 
> This file is only compiled with CONFIG_RISCV_PMU:

I might be ill, but I can still read. I was not disagreeing with Xiao
that the condition is redundant as written - I want to know whether they
made sure that this check was intentionally using CONFIG_RISCV_PMU in the
first place, or if another option should have been here instead.

> 
> # drivers/perf/Makefile
> obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
> 
> So having this check does seem redundant. I am copying Alex as it looks
> like he wrote this.
> 
> - Charlie
> 
> > 
> > Cheers,
> > Conor.
> > 
> > > 
> > > Signed-off-by: Xiao Wang <xiao.w.wang@...el.com>
> > > ---
> > >  drivers/perf/riscv_pmu.c | 2 --
> > >  1 file changed, 2 deletions(-)
> > > 
> > > diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> > > index 0a02e85a8951..7644147d50b4 100644
> > > --- a/drivers/perf/riscv_pmu.c
> > > +++ b/drivers/perf/riscv_pmu.c
> > > @@ -39,7 +39,6 @@ void arch_perf_update_userpage(struct perf_event *event,
> > >  	userpg->cap_user_time_short = 0;
> > >  	userpg->cap_user_rdpmc = riscv_perf_user_access(event);
> > >  
> > > -#ifdef CONFIG_RISCV_PMU
> > >  	/*
> > >  	 * The counters are 64-bit but the priv spec doesn't mandate all the
> > >  	 * bits to be implemented: that's why, counter width can vary based on
> > > @@ -47,7 +46,6 @@ void arch_perf_update_userpage(struct perf_event *event,
> > >  	 */
> > >  	if (userpg->cap_user_rdpmc)
> > >  		userpg->pmc_width = to_riscv_pmu(event->pmu)->ctr_get_width(event->hw.idx) + 1;
> > > -#endif
> > >  
> > >  	do {
> > >  		rd = sched_clock_read_begin(&seq);
> > > -- 
> > > 2.25.1
> > > 
> > > 
> > > _______________________________________________
> > > linux-riscv mailing list
> > > linux-riscv@...ts.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> 

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