linux-kernel - Re: [PATCH v3 05/17] usb: typec: Add device managed typec_switch

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Message-ID: <CAE-0n52FSUFictNQ9kotgFAZPYnJpy+3Ad__QeUN+EiJuBWGwQ@mail.gmail.com>
Date: Tue, 20 Aug 2024 10:19:48 -0700
From: Stephen Boyd <swboyd@...omium.org>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	patches@...ts.linux.dev, devicetree@...r.kernel.org, 
	Douglas Anderson <dianders@...omium.org>, Pin-yen Lin <treapking@...omium.org>, 
	Andrzej Hajda <andrzej.hajda@...el.com>, Benson Leung <bleung@...omium.org>, 
	Conor Dooley <conor+dt@...nel.org>, Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...il.com>, 
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, dri-devel@...ts.freedesktop.org, 
	Guenter Roeck <groeck@...omium.org>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	Jonas Karlman <jonas@...boo.se>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>, Lee Jones <lee@...nel.org>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Prashant Malani <pmalani@...omium.org>, 
	Robert Foss <rfoss@...nel.org>, Rob Herring <robh+dt@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, Tzung-Bi Shih <tzungbi@...nel.org>, 
	Alexandre Belloni <alexandre.belloni@...tlin.com>, Daniel Scally <djrscally@...il.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>, Ivan Orlov <ivan.orlov0322@...il.com>, 
	linux-acpi@...r.kernel.org, linux-usb@...r.kernel.org, 
	Mika Westerberg <mika.westerberg@...ux.intel.com>, 
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>, Sakari Ailus <sakari.ailus@...ux.intel.com>, 
	Vinod Koul <vkoul@...nel.org>
Subject: Re: [PATCH v3 05/17] usb: typec: Add device managed typec_switch_register()

Quoting Andy Shevchenko (2024-08-20 10:16:40)
> On Tue, Aug 20, 2024 at 10:01:07AM -0700, Stephen Boyd wrote:
> > Quoting Andy Shevchenko (2024-08-20 03:16:09)
> > > On Mon, Aug 19, 2024 at 03:38:19PM -0700, Stephen Boyd wrote:
> > > > +     ptr = devres_alloc(devm_typec_switch_unregister, sizeof(*ptr), GFP_KERNEL);
> > > > +     if (!ptr)
> > > > +             return ERR_PTR(-ENOMEM);
> > > > +
> > > > +     switch_dev = typec_switch_register(parent ,desc);
>
> (Side note: wrong location of the white space)

Thanks.

>
> > > > +     if (!IS_ERR(switch_dev)) {
>
> (Side note: positive conditional is okay)
>
> > > > +             *ptr = switch_dev;
> > > > +             devres_add(parent, ptr);
> > > > +     } else {
> > > > +             devres_free(ptr);
> > > > +     }
> > >
> > > devm_add_action_or_reset() ?
> >
> > No. We don't want to call the 'action' devm_typec_switch_unregister()
> > when it fails because that would unregister a switch that has never been
> > registered.
>
> Hmm... With devm_add_action_or_reset() we first do things and then try to add
> them to the managed resources. In that case it won't be like you described.
>
> What do I miss?
>

I believe you've missed that this is a wrapper around struct device and
the error path is different (put_device() vs. device_unregister()).