linux-kernel - Re: [External] Re: [PATCH] perf/dwc_pcie: fix duplicate pci

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Message-ID: <CAEEQ3wnTMfWSZRhTax3N60W=m3a=zxnJF6dOfiGnqJzBQs8WEg@mail.gmail.com>
Date: Sun, 26 Jan 2025 09:54:35 +0800
From: yunhui cui <cuiyunhui@...edance.com>
To: Will Deacon <will@...nel.org>
Cc: Shuai Xue <xueshuai@...ux.alibaba.com>, renyu.zj@...ux.alibaba.com, 
	mark.rutland@....com, linux-arm-kernel@...ts.infradead.org, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [External] Re: [PATCH] perf/dwc_pcie: fix duplicate pci_dev devices

Hi Will,

On Fri, Jan 24, 2025 at 8:30 PM Will Deacon <will@...nel.org> wrote:
>
> On Fri, Jan 24, 2025 at 05:11:05PM +0800, yunhui cui wrote:
> > > >>>        vsec = dwc_pcie_des_cap(pdev);
> > > >>>        if (!vsec)
> > > >>>                return -ENODEV;
> > > >>>
> > > >>>        sbdf = plat_dev->id;
> > > >>> -     name = devm_kasprintf(&plat_dev->dev, GFP_KERNEL, "dwc_rootport_%x", sbdf);
> > > >>> +     name = devm_kasprintf(&plat_dev->dev, GFP_KERNEL, "dwc_rootport_%d_pmu", sbdf);
> > > >>
> > > >> A new name will break previous user tools.
> > > > This name isn't suitable. It can't clearly show which is the PMU
> > > > device. Userspace tools don't have binding relationships, like perf.
> > > > Tools must traverse PMU devices before use.
> > >
> > > The device is under /sys/bus/event_source/ which indates it is PMU device.
> > > As far as I know, most of PMU devices do not endup with a '_pmu' prefix.
> >
> > The point is the name "dwc_rootport_" is misleading, suggesting an
> > extra PCIE RP in the system. Best to change the name to intuitive
> > "xx_pmu".
>
> As pointed out above, changing the name will break userspace. So it's
> simply not an option, sorry.

Could you specify what in the userspace is broken and give an example?

>
> Will

Thanks,
Yunhui