On Saturday, May 04, 2013 02:51:16 PM Pavel Machek wrote:
> Hi!
>
> > dev_pm_put_subsys_data() calls kfree() while holding device power lock, when
> > the reference count is 0. Fix it to call kfree() after releasing the lock.
> >
> > Signed-off-by: Shuah Khan <[email protected]>
> > ---
> > drivers/base/power/common.c | 6 +++++-
> > 1 file changed, 5 insertions(+), 1 deletion(-)
> >
> w> diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
> > index 39c3252..da05fe2 100644
> > --- a/drivers/base/power/common.c
> > +++ b/drivers/base/power/common.c
> > @@ -73,13 +73,17 @@ int dev_pm_put_subsys_data(struct device *dev)
> >
> > if (--psd->refcount == 0) {
> > dev->power.subsys_data = NULL;
> > - kfree(psd);
> > ret = 1;
> > }
> >
> > out:
> > spin_unlock_irq(&dev->power.lock);
> >
> > + if (ret == 1) {
> > + /* kfree() verifies that its argument is nonzero. */
> > + kfree(psd);
> > + }
> > +
> > return ret;
> > }
>
> Wow, that function is fragile. It returns 0/1/-EINVAL, while being
> documented for 0/1...
Oh, it generally should return 1 for !psd.
> Patch does not look obviously wrong, but maybe
>
> @@ -73,13 +73,17 @@ int dev_pm_put_subsys_data(struct device *dev)
>
> if (--psd->refcount == 0) {
> dev->power.subsys_data = NULL;
> + spin_unlock_irq(&dev->power.lock);
> - kfree(psd);
> - ret = 1;
> + return 1;
> }
>
> Would be cleaner.
What about this:
---
drivers/base/power/common.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
Index: linux-pm/drivers/base/power/common.c
===================================================================
--- linux-pm.orig/drivers/base/power/common.c
+++ linux-pm/drivers/base/power/common.c
@@ -61,24 +61,24 @@ EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data
int dev_pm_put_subsys_data(struct device *dev)
{
struct pm_subsys_data *psd;
- int ret = 0;
+ int ret = 1;
spin_lock_irq(&dev->power.lock);
psd = dev_to_psd(dev);
- if (!psd) {
- ret = -EINVAL;
+ if (!psd)
goto out;
- }
if (--psd->refcount == 0) {
dev->power.subsys_data = NULL;
- kfree(psd);
- ret = 1;
+ } else {
+ psd = NULL;
+ ret = 0;
}
out:
spin_unlock_irq(&dev->power.lock);
+ kfree(psd);
return ret;
}
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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