Re: [PATCH] PM / wakeup: Avoid dev_name collisions in wakeup class

From: Tri Vo <trong@android.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Stephen Boyd <swboyd@chromium.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux PM <linux-pm@vger.kernel.org>,
	Kalesh Singh <kaleshsingh@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ravi Chandra Sadineni <ravisadineni@chromium.org>
Subject: Re: [PATCH] PM / wakeup: Avoid dev_name collisions in wakeup class
Date: Sat, 27 Jul 2019 10:37:07 -0700	[thread overview]
Message-ID: <CANA+-vDNkSG39SLd0_B_L8gkDkfQ2uJLcuvCaRgHkU8DiBzMTw@mail.gmail.com> (raw)
In-Reply-To: <CAJZ5v0hroRuGQ5N42Z8=yFVXiJPdid3wJrHoKqr2BZVx=sfnBQ@mail.gmail.com>

On Sat, Jul 27, 2019 at 6:10 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Sat, Jul 27, 2019 at 3:11 AM Stephen Boyd <swboyd@chromium.org> wrote:
> >
> > If a device is wakeup capable and the driver calls device_wakeup_init()
> > on it during probe and then userspace writes 'enabled' to that device's
> > power/wakeup file in sysfs we'll try to create the same named wakeup
> > device in sysfs. The kernel will complain about duplicate file names.

Thanks for reporting the issue, Stephen!
> >
> > sysfs: cannot create duplicate filename '/devices/virtual/wakeup/1-1.1'
> > kobject_add_internal failed for 1-1.1 with -EEXIST, don't try to register things with the same name in the same directory.
> >
> > It may be advantageous to not write 'enabled' to the wakeup file (see
> > wakeup_store()) from userspace for these devices because we allocate
> > devices and register them and then throw them all away later on if the
> > device driver has already initialized the wakeup attribute. The
> > implementation currently tries to avoid taking locks here so it seems
> > best to optimize that path in a separate patch.
> >
> > Let's rename the wakeup class devices as 'wakeupN' with an IDA that's
> > simple enough to just return some sort of number. In addition, let's
> > make the device registering the wakeup the parent and include a 'name'
> > attribute in case userspace wants to figure out the type of wakeup it is
> > (in the case of virtual wakeups) or the device associated with the
> > wakeup. This makes it easier for userspace to go from /sys/class/wakeup
> > to a place in the device hierarchy where the wakeup is generated from
> > like an input device.
> >
> > Cc: Tri Vo <trong@android.com>
> > Cc: Kalesh Singh <kaleshsingh@google.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: Ravi Chandra Sadineni <ravisadineni@chromium.org>
> > Signed-off-by: Stephen Boyd <swboyd@chromium.org>
>
> I'd rather change the commit that introduced this issue which is only
> in linux-next for now.

Raphael, could you roll back my patch? I'll work with Stephen to fix it.