linux-kernel - Re: [PATCH v2 1/7] device core: add BUS_NOTIFY_BIND_DRIVER

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Date:	Fri, 27 Nov 2015 11:46:20 +0200
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	linux-acpi@...r.kernel.org, Vinod Koul <vinod.koul@...el.com>,
	dmaengine@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH v2 1/7] device core: add BUS_NOTIFY_BIND_DRIVER_ERROR
 notification

On Fri, 2015-11-27 at 00:09 +0100, Rafael J. Wysocki wrote:
> On Thursday, November 26, 2015 05:19:07 PM Andy Shevchenko wrote:
> > In case ->probe() fails the notifier does not inform a subscriber
> > about this.
> > In the result it might happend that some resources that had been
> > allocated will
> > stay allocated and therefore lead to resource leak.
> > 
> > Introduce a new notification to inform the subscriber that
> > ->probe() failed.
> > 
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> 
> I'd rather say the problem is that the users of
> BUS_NOTIFY_BIND_DRIVER have no
> chance to do any cleanup in case of a probe failure (there may be
> problems even
> if resources aren't leaked).

Thanks, Rafael, all of your comments sound reasonable for me. Will be
taken into consideration in next version.

> 
> > ---
> >  drivers/base/dd.c      | 8 ++++++--
> >  include/linux/device.h | 1 +
> >  2 files changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> > index a641cf3..ac071a5 100644
> > --- a/drivers/base/dd.c
> > +++ b/drivers/base/dd.c
> > @@ -290,7 +290,7 @@ static int really_probe(struct device *dev,
> > struct device_driver *drv)
> >  	/* If using pinctrl, bind pins now before probing */
> >  	ret = pinctrl_bind_pins(dev);
> >  	if (ret)
> > -		goto probe_failed;
> > +		goto pinctrl_bind_failed;
> >  
> >  	if (driver_sysfs_add(dev)) {
> >  		printk(KERN_ERR "%s: driver_sysfs_add(%s)
> > failed\n",
> > @@ -334,6 +334,11 @@ static int really_probe(struct device *dev,
> > struct device_driver *drv)
> >  	goto done;
> >  
> >  probe_failed:
> > +	if (dev->bus)
> > +		blocking_notifier_call_chain(&dev->bus->p-
> > >bus_notifier,
> > +					     BUS_NOTIFY_BIND_DRIVE
> > R_ERROR,
> > +					     dev);
> 
> Well, if we do that, device_bind_driver() needs to send that
> notification too
> in case it doesn't call driver_bound().
> 
> > +pinctrl_bind_failed:
> >  	devres_release_all(dev);
> >  	driver_sysfs_remove(dev);
> >  	dev->driver = NULL;
> > @@ -701,7 +706,6 @@ static void __device_release_driver(struct
> > device *dev)
> >  			blocking_notifier_call_chain(&dev->bus->p-
> > >bus_notifier,
> >  						     BUS_NOTIFY_UN
> > BOUND_DRIVER,
> >  						     dev);
> > -
> >  	}
> >  }
> >  
> > diff --git a/include/linux/device.h b/include/linux/device.h
> > index b8f411b..87cf423 100644
> > --- a/include/linux/device.h
> > +++ b/include/linux/device.h
> > @@ -191,6 +191,7 @@ extern int bus_unregister_notifier(struct
> > bus_type *bus,
> >  						      unbound */
> >  #define BUS_NOTIFY_UNBOUND_DRIVER	0x00000007 /* driver is
> > unbound
> >  						      from the
> > device */
> > +#define BUS_NOTIFY_BIND_DRIVER_ERROR	0x80000004 /* driver
> > fails to be bound */
> 
> I'd call it BUS_NOTIFY_DRIVER_NOT_BOUND.
> 
> >  
> >  extern struct kset *bus_get_kset(struct bus_type *bus);
> >  extern struct klist *bus_get_device_klist(struct bus_type *bus);
> > 
> 
> Thanks,
> Rafael
> 

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy

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