2008-01-30 01:55:38

by Dave Young

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

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

Signed-off-by: Dave Young <[email protected]>

---
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);


2008-01-30 10:33:26

by Cornelia Huck

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

On Wed, 30 Jan 2008 09:56:25 +0800,
Dave Young <[email protected]> wrote:

> get dev reference before create/remove sysfiles, errno fixes as well.
>
> Signed-off-by: Dave Young <[email protected]>
>
> ---
> 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);

2008-01-31 01:17:34

by Dave Young

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

On Jan 30, 2008 6:32 PM, Cornelia Huck <[email protected]> wrote:
> On Wed, 30 Jan 2008 09:56:25 +0800,
> Dave Young <[email protected]> wrote:
>
> > get dev reference before create/remove sysfiles, errno fixes as well.
> >
> > Signed-off-by: Dave Young <[email protected]>
> >
> > ---
> > 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);
>

2008-01-31 09:39:58

by Cornelia Huck

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

On Thu, 31 Jan 2008 09:17:18 +0800,
"Dave Young" <[email protected]> wrote:

> On Jan 30, 2008 6:32 PM, Cornelia Huck <[email protected]> wrote:
> > On Wed, 30 Jan 2008 09:56:25 +0800,
> > Dave Young <[email protected]> wrote:
> >
> > > get dev reference before create/remove sysfiles, errno fixes as well.
> > >
> > > Signed-off-by: Dave Young <[email protected]>
> > >
> > > ---
> > > 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 <[email protected]>

---
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);