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    Subject[PATCH 09/50] sysdev: Do not register with sysdev when erroring on add
    Date
    From: Borislav Petkov <borislav.petkov@amd.com>

    When encountering an error while executing the driver's ->add method, we
    should cancel registration and unwind what we've regged so far. The low
    level ->add methods do return proper error codes but those aren't looked
    at in sysdev_driver_register(). Fix that by sharing the unregistering
    code.

    Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    ---
    drivers/base/sys.c | 61 +++++++++++++++++++++++++++++++++++++--------------
    1 files changed, 44 insertions(+), 17 deletions(-)

    diff --git a/drivers/base/sys.c b/drivers/base/sys.c
    index b094e0d..f6fb547 100644
    --- a/drivers/base/sys.c
    +++ b/drivers/base/sys.c
    @@ -166,6 +166,36 @@ EXPORT_SYMBOL_GPL(sysdev_class_unregister);

    static DEFINE_MUTEX(sysdev_drivers_lock);

    +/*
    + * @dev != NULL means that we're unwinding because some drv->add()
    + * failed for some reason. You need to grab sysdev_drivers_lock before
    + * calling this.
    + */
    +static void __sysdev_driver_remove(struct sysdev_class *cls,
    + struct sysdev_driver *drv,
    + struct sys_device *from_dev)
    +{
    + struct sys_device *dev = from_dev;
    +
    + list_del_init(&drv->entry);
    + if (!cls)
    + return;
    +
    + if (!drv->remove)
    + goto kset_put;
    +
    + if (dev)
    + list_for_each_entry_continue_reverse(dev, &cls->kset.list,
    + kobj.entry)
    + drv->remove(dev);
    + else
    + list_for_each_entry(dev, &cls->kset.list, kobj.entry)
    + drv->remove(dev);
    +
    +kset_put:
    + kset_put(&cls->kset);
    +}
    +
    /**
    * sysdev_driver_register - Register auxillary driver
    * @cls: Device class driver belongs to.
    @@ -175,9 +205,9 @@ static DEFINE_MUTEX(sysdev_drivers_lock);
    * called on each operation on devices of that class. The refcount
    * of @cls is incremented.
    */
    -
    int sysdev_driver_register(struct sysdev_class *cls, struct sysdev_driver *drv)
    {
    + struct sys_device *dev = NULL;
    int err = 0;

    if (!cls) {
    @@ -198,19 +228,27 @@ int sysdev_driver_register(struct sysdev_class *cls, struct sysdev_driver *drv)

    /* If devices of this class already exist, tell the driver */
    if (drv->add) {
    - struct sys_device *dev;
    - list_for_each_entry(dev, &cls->kset.list, kobj.entry)
    - drv->add(dev);
    + list_for_each_entry(dev, &cls->kset.list, kobj.entry) {
    + err = drv->add(dev);
    + if (err)
    + goto unwind;
    + }
    }
    } else {
    err = -EINVAL;
    WARN(1, KERN_ERR "%s: invalid device class\n", __func__);
    }
    +
    + goto unlock;
    +
    +unwind:
    + __sysdev_driver_remove(cls, drv, dev);
    +
    +unlock:
    mutex_unlock(&sysdev_drivers_lock);
    return err;
    }

    -
    /**
    * sysdev_driver_unregister - Remove an auxillary driver.
    * @cls: Class driver belongs to.
    @@ -220,23 +258,12 @@ void sysdev_driver_unregister(struct sysdev_class *cls,
    struct sysdev_driver *drv)
    {
    mutex_lock(&sysdev_drivers_lock);
    - list_del_init(&drv->entry);
    - if (cls) {
    - if (drv->remove) {
    - struct sys_device *dev;
    - list_for_each_entry(dev, &cls->kset.list, kobj.entry)
    - drv->remove(dev);
    - }
    - kset_put(&cls->kset);
    - }
    + __sysdev_driver_remove(cls, drv, NULL);
    mutex_unlock(&sysdev_drivers_lock);
    }
    -
    EXPORT_SYMBOL_GPL(sysdev_driver_register);
    EXPORT_SYMBOL_GPL(sysdev_driver_unregister);

    -
    -
    /**
    * sysdev_register - add a system device to the tree
    * @sysdev: device in question
    --
    1.7.4.1


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