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SubjectRe: [PATCH v3 1/3] msi: free msi_desc entry only after we've released the kobject
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On Tue, Oct 29, 2013 at 3:30 AM, Veaceslav Falico <vfalico@redhat.com> wrote:
> /*
> * Its possible that we get into this path
> * When populate_msi_sysfs fails, which means the entries
> * were not registered with sysfs. In that case don't
> - * unregister them.
> + * unregister them, and just free. Otherwise the
> + * kobject->release will take care of freeing the entry via
> + * msi_kobj_release().
> */
> if (entry->kobj.parent) {
> kobject_del(&entry->kobj);
> kobject_put(&entry->kobj);
> + } else {
> + kfree(entry);
> }
> -
> - list_del(&entry->list);
> - kfree(entry);

So this code sequence still makes me very unhappy.

Why does not just a simple unconditional

kobject_del(&entry->kobj);
kobject_put(&entry->kobj);

work for the "not registered with sysfs" case? And if the sysfs code
really gets confused, why not

if (entry->kobj.parent)
kobject_del(&entry->kobj);
kobject_put(&entry->kobj);

(btw, looking at the sysfs code, this looks *very* suspicious in
sysfs_remove_dir():

struct sysfs_dirent *sd = kobj->sd;

spin_lock(&sysfs_assoc_lock);
kobj->sd = NULL;
spin_unlock(&sysfs_assoc_lock);

and I would suggest that "sd = kobj->sd" should be done under the
lock, because otherwise the lock is kind of pointless..)

Greg?

Linus


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