Jarkko,
On Fri, Oct 16, 2015 at 09:40:22PM +0300, Jarkko Sakkinen wrote:
> Added a new function __compat_only_sysfs_link_group_to_kobj() that adds
> a symlink from attribute or group to a kobject. This needed for
> maintaining backwards compatibility with PPI attributes in the TPM
> driver.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
> ---
> fs/sysfs/group.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/sysfs.h | 11 +++++++++++
> 2 files changed, 55 insertions(+)
>
> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> index 39a0199..e123659 100644
> --- a/fs/sysfs/group.c
> +++ b/fs/sysfs/group.c
> @@ -352,3 +352,47 @@ void sysfs_remove_link_from_group(struct kobject *kobj,
> const char *group_name,
> }
> }
> EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
> +
> +/**
> + * __compat_only_sysfs_link_entry_to_kobj - add a symlink to a kobject
> pointing
> + * to a group or an attribute
> + * @kobj: The kobject containing the group.
> + * @target_kobj: The target kobject.
> + * @target_name: The name of the target group or attribute.
> + */
> +int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
> + struct kobject *target_kobj,
> + const char *target_name)
> +{
> + struct kernfs_node *target;
> + struct kernfs_node *entry;
> + struct kernfs_node *link;
> +
> + /*
> + * We don't own @target_kobj and it may be removed at any time.
> + * Synchronize using sysfs_symlink_target_lock. See sysfs_remove_dir()
> + * for details.
> + */
> + spin_lock(&sysfs_symlink_target_lock);
> + target = target_kobj->sd;
> + if (target)
> + kernfs_get(target);
> + spin_unlock(&sysfs_symlink_target_lock);
> + if (!target)
> + return -ENOENT;
> +
> + entry = kernfs_find_and_get(target_kobj->sd, target_name);
> + if (!entry) {
> + kernfs_put(target);
> + return -ENOENT;
> + }
> +
On an Acer C720 this call to kernfs_find_and_get fails resulting in
a failed resume after suspend.
Apparently it can't find an object for the name "ppi".
This bug does not appear until the next patch is applied which
calls __compat_only_sysfs_link_entry_to_kobj.
[...]
--
- Jeremiah Mahler
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