[PATCH] driver-core : get_device before create/remove sysfs files

[PATCH] driver-core : get_device before create/remove sysfs files

[Dave Young]

get dev reference before create/remove sysfiles, errno fixes as well.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com> 

---
drivers/base/core.c |   12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff -upr a/drivers/base/core.c b/drivers/base/core.c
--- a/drivers/base/core.c	2008-01-30 09:49:56.000000000 +0800
+++ b/drivers/base/core.c	2008-01-30 09:49:56.000000000 +0800
@@ -414,7 +414,7 @@ struct kset *devices_kset;
  */
 int device_create_file(struct device *dev, struct device_attribute *attr)
 {
-	int error = 0;
+	int error = -ENODEV;
 	if (get_device(dev)) {
 		error = sysfs_create_file(&dev->kobj, &attr->attr);
 		put_device(dev);
@@ -442,9 +442,11 @@ void device_remove_file(struct device *d
  */
 int device_create_bin_file(struct device *dev, struct bin_attribute *attr)
 {
-	int error = -EINVAL;
-	if (dev)
+	int error = -ENODEV;
+	if (get_device(dev)) {
 		error = sysfs_create_bin_file(&dev->kobj, attr);
+		put_device(dev);
+	}
 	return error;
 }
 EXPORT_SYMBOL_GPL(device_create_bin_file);
@@ -456,8 +458,10 @@ EXPORT_SYMBOL_GPL(device_create_bin_file
  */
 void device_remove_bin_file(struct device *dev, struct bin_attribute *attr)
 {
-	if (dev)
+	if (get_device(dev)) {
 		sysfs_remove_bin_file(&dev->kobj, attr);
+		put_device(dev);
+	}
 }
 EXPORT_SYMBOL_GPL(device_remove_bin_file);
 

Re: [PATCH] driver-core : get_device before create/remove sysfs files

[Cornelia Huck]

On Wed, 30 Jan 2008 09:56:25 +0800,
Dave Young <hidave.darkstar@gmail.com> wrote:

> get dev reference before create/remove sysfiles, errno fixes as well.
> 
> Signed-off-by: Dave Young <hidave.darkstar@gmail.com> 
> 
> ---
> drivers/base/core.c |   12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff -upr a/drivers/base/core.c b/drivers/base/core.c
> --- a/drivers/base/core.c	2008-01-30 09:49:56.000000000 +0800
> +++ b/drivers/base/core.c	2008-01-30 09:49:56.000000000 +0800
> @@ -414,7 +414,7 @@ struct kset *devices_kset;
>   */
>  int device_create_file(struct device *dev, struct device_attribute *attr)
>  {
> -	int error = 0;
> +	int error = -ENODEV;

Uhm... why?

>  	if (get_device(dev)) {
>  		error = sysfs_create_file(&dev->kobj, &attr->attr);
>  		put_device(dev);
> @@ -442,9 +442,11 @@ void device_remove_file(struct device *d
>   */
>  int device_create_bin_file(struct device *dev, struct bin_attribute *attr)
>  {
> -	int error = -EINVAL;
> -	if (dev)
> +	int error = -ENODEV;
> +	if (get_device(dev)) {
>  		error = sysfs_create_bin_file(&dev->kobj, attr);
> +		put_device(dev);
> +	}

Why do we need to grab a reference here? If the calling site doesn't
hold unto a reference already, something is seriously broken.

>  	return error;
>  }
>  EXPORT_SYMBOL_GPL(device_create_bin_file);
> @@ -456,8 +458,10 @@ EXPORT_SYMBOL_GPL(device_create_bin_file
>   */
>  void device_remove_bin_file(struct device *dev, struct bin_attribute *attr)
>  {
> -	if (dev)
> +	if (get_device(dev)) {
>  		sysfs_remove_bin_file(&dev->kobj, attr);
> +		put_device(dev);
> +	}

Dito.

>  }
>  EXPORT_SYMBOL_GPL(device_remove_bin_file);

Re: [PATCH] driver-core : get_device before create/remove sysfs files

[Dave Young]

On Jan 30, 2008 6:32 PM, Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> On Wed, 30 Jan 2008 09:56:25 +0800,
> Dave Young <hidave.darkstar@gmail.com> wrote:
>
> > get dev reference before create/remove sysfiles, errno fixes as well.
> >
> > Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
> >
> > ---
> > drivers/base/core.c |   12 ++++++++----
> > 1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff -upr a/drivers/base/core.c b/drivers/base/core.c
> > --- a/drivers/base/core.c     2008-01-30 09:49:56.000000000 +0800
> > +++ b/drivers/base/core.c     2008-01-30 09:49:56.000000000 +0800
> > @@ -414,7 +414,7 @@ struct kset *devices_kset;
> >   */
> >  int device_create_file(struct device *dev, struct device_attribute *attr)
> >  {
> > -     int error = 0;
> > +     int error = -ENODEV;
>
> Uhm... why?

In this function :
        if (get_device(dev)) {
                do create issue
        }
        return error

So IMO the initial error should be -ENODEV

>
> >       if (get_device(dev)) {
> >               error = sysfs_create_file(&dev->kobj, &attr->attr);
> >               put_device(dev);
> > @@ -442,9 +442,11 @@ void device_remove_file(struct device *d
> >   */
> >  int device_create_bin_file(struct device *dev, struct bin_attribute *attr)
> >  {
> > -     int error = -EINVAL;
> > -     if (dev)
> > +     int error = -ENODEV;
> > +     if (get_device(dev)) {
> >               error = sysfs_create_bin_file(&dev->kobj, attr);
> > +             put_device(dev);
> > +     }
>
> Why do we need to grab a reference here? If the calling site doesn't
> hold unto a reference already, something is seriously broken.

First, we should keep consistent with previous function "device_create_file";
Second, AFAIK this function mostly are called after something like device_add
and the dev reference are not hold.


>
> >       return error;
> >  }
> >  EXPORT_SYMBOL_GPL(device_create_bin_file);
> > @@ -456,8 +458,10 @@ EXPORT_SYMBOL_GPL(device_create_bin_file
> >   */
> >  void device_remove_bin_file(struct device *dev, struct bin_attribute *attr)
> >  {
> > -     if (dev)
> > +     if (get_device(dev)) {
> >               sysfs_remove_bin_file(&dev->kobj, attr);
> > +             put_device(dev);
> > +     }
>
> Dito.
>
>
> >  }
> >  EXPORT_SYMBOL_GPL(device_remove_bin_file);
>

Re: [PATCH] driver-core : get_device before create/remove sysfs files

[Cornelia Huck]

On Thu, 31 Jan 2008 09:17:18 +0800,
"Dave Young" <hidave.darkstar@gmail.com> wrote:

> On Jan 30, 2008 6:32 PM, Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> > On Wed, 30 Jan 2008 09:56:25 +0800,
> > Dave Young <hidave.darkstar@gmail.com> wrote:
> >
> > > get dev reference before create/remove sysfiles, errno fixes as well.
> > >
> > > Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
> > >
> > > ---
> > > drivers/base/core.c |   12 ++++++++----
> > > 1 file changed, 8 insertions(+), 4 deletions(-)
> > >
> > > diff -upr a/drivers/base/core.c b/drivers/base/core.c
> > > --- a/drivers/base/core.c     2008-01-30 09:49:56.000000000 +0800
> > > +++ b/drivers/base/core.c     2008-01-30 09:49:56.000000000 +0800
> > > @@ -414,7 +414,7 @@ struct kset *devices_kset;
> > >   */
> > >  int device_create_file(struct device *dev, struct device_attribute *attr)
> > >  {
> > > -     int error = 0;
> > > +     int error = -ENODEV;
> >
> > Uhm... why?
> 
> In this function :
>         if (get_device(dev)) {
>                 do create issue
>         }
>         return error
> 
> So IMO the initial error should be -ENODEV

If everybody can agree on returning this error in case of dev == NULL,
OK. But please don't mix changing the function's semantics with the
other changes.

> 
> >
> > >       if (get_device(dev)) {
> > >               error = sysfs_create_file(&dev->kobj, &attr->attr);
> > >               put_device(dev);
> > > @@ -442,9 +442,11 @@ void device_remove_file(struct device *d
> > >   */
> > >  int device_create_bin_file(struct device *dev, struct bin_attribute *attr)
> > >  {
> > > -     int error = -EINVAL;
> > > -     if (dev)
> > > +     int error = -ENODEV;
> > > +     if (get_device(dev)) {
> > >               error = sysfs_create_bin_file(&dev->kobj, attr);
> > > +             put_device(dev);
> > > +     }
> >
> > Why do we need to grab a reference here? If the calling site doesn't
> > hold unto a reference already, something is seriously broken.
> 
> First, we should keep consistent with previous function "device_create_file";

I'd rather think that device_create_file() should be changed (see patch
below).

> Second, AFAIK this function mostly are called after something like device_add
> and the dev reference are not hold.

That code holds the reference acquired through device_initialize().

I think we should just get rid of those get/put games:


Driver core: Remove unneeded get_{device,driver}() calls.

Code trying to add/remove attributes must hold a reference to
the device resp. driver anyway, so let's remove those reference
count games.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

---
 drivers/base/core.c   |    8 ++------
 drivers/base/driver.c |    9 +++------
 2 files changed, 5 insertions(+), 12 deletions(-)

--- linux-2.6.orig/drivers/base/core.c
+++ linux-2.6/drivers/base/core.c
@@ -423,10 +423,8 @@ struct kset *devices_kset;
 int device_create_file(struct device *dev, struct device_attribute *attr)
 {
 	int error = 0;
-	if (get_device(dev)) {
+	if (dev)
 		error = sysfs_create_file(&dev->kobj, &attr->attr);
-		put_device(dev);
-	}
 	return error;
 }
 
@@ -437,10 +435,8 @@ int device_create_file(struct device *de
  */
 void device_remove_file(struct device *dev, struct device_attribute *attr)
 {
-	if (get_device(dev)) {
+	if (dev)
 		sysfs_remove_file(&dev->kobj, &attr->attr);
-		put_device(dev);
-	}
 }
 
 /**
--- linux-2.6.orig/drivers/base/driver.c
+++ linux-2.6/drivers/base/driver.c
@@ -97,10 +97,9 @@ int driver_create_file(struct device_dri
 		       struct driver_attribute *attr)
 {
 	int error;
-	if (get_driver(drv)) {
+	if (drv)
 		error = sysfs_create_file(&drv->p->kobj, &attr->attr);
-		put_driver(drv);
-	} else
+	else
 		error = -EINVAL;
 	return error;
 }
@@ -114,10 +113,8 @@ EXPORT_SYMBOL_GPL(driver_create_file);
 void driver_remove_file(struct device_driver *drv,
 			struct driver_attribute *attr)
 {
-	if (get_driver(drv)) {
+	if (drv)
 		sysfs_remove_file(&drv->p->kobj, &attr->attr);
-		put_driver(drv);
-	}
 }
 EXPORT_SYMBOL_GPL(driver_remove_file);