linux-kernel - Re: [PATCH v3 09/11] platform/x86/intel/ifs: Add IFS sysfs interface

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Message-ID: <CAPcyv4haH561eC_+oPj8PMdf2510BDq7==orHNLoHPm0d16k2w@mail.gmail.com>
Date:   Tue, 19 Apr 2022 11:15:05 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     "Luck, Tony" <tony.luck@...el.com>,
        Hans de Goede <hdegoede@...hat.com>, markgross@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Jonathan Corbet <corbet@....net>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Joseph, Jithu" <jithu.joseph@...el.com>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org, patches@...ts.linux.dev,
        Ravi V Shankar <ravi.v.shankar@...el.com>
Subject: Re: [PATCH v3 09/11] platform/x86/intel/ifs: Add IFS sysfs interface

On Tue, Apr 19, 2022 at 11:01 AM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Tue, Apr 19, 2022 at 10:35:17AM -0700, Luck, Tony wrote:
> > On Tue, Apr 19, 2022 at 07:20:54PM +0200, Greg KH wrote:
> > > > +/*
> > > > + * Note there is no need for a ->remove() call back. There isn't an
> > > > + * "unload" operation to remove the scan binary from the BIOS reserved
> > > > + * area. Also ".dev_groups" removal order will guarantee that any in
> > > > + * flight tests have completed.
> > > > + */
> > >
> > > So you are ok with the warning the kernel gives you when you unload the
> > > driver?  That feels wrong :(
> >
> > What warning?
> >
> > # dmesg | tail -5
> > [   38.084165] virbr0: port 1(virbr0-nic) entered listening state
> > [   38.149621] virbr0: port 1(virbr0-nic) entered disabled state
> > [   38.582054] broken atomic modeset userspace detected, disabling atomic
> > [   43.703321] igc 0000:01:00.0 enp1s0: NIC Link is Up 2500 Mbps Full Duplex, Flow Control: RX
> > [   43.703470] IPv6: ADDRCONF(NETDEV_CHANGE): enp1s0: link becomes ready
> > # modprobe intel_ifs
> > # ls /sys/devices/platform/intel_ifs.0/
> > details  driver_override  modalias  reload    status     uevent
> > driver   image_version    power     run_test  subsystem
> > # rmmod intel_ifs
> > # dmesg | tail -5
> > [   38.084165] virbr0: port 1(virbr0-nic) entered listening state
> > [   38.149621] virbr0: port 1(virbr0-nic) entered disabled state
> > [   38.582054] broken atomic modeset userspace detected, disabling atomic
> > [   43.703321] igc 0000:01:00.0 enp1s0: NIC Link is Up 2500 Mbps Full Duplex, Flow Control: RX
> > [   43.703470] IPv6: ADDRCONF(NETDEV_CHANGE): enp1s0: link becomes ready
> > #
>
> If there's no warning when the device goes away, why the crazy comment
> trying to justify the lack of a remove callback?

The comment clarifies the nuance that driver.dev_groups coordinates
flushing access sysfs ops users before ->remove() is called. It can
certainly be dropped.