On Thu, Sep 24, 2015 at 2:36 PM, Russell King
<rmk+kernel@xxxxxxxxxxxxxxxx> wrote:
> bus_find_device() is defined as:
>
> * This is similar to the bus_for_each_dev() function above, but it
> * returns a reference to a device that is 'found' for later use, as
> * determined by the @match callback.
>
> and it does indeed return a reference-counted pointer to the device:
>
> while ((dev = next_device(&i)))
> if (match(dev, data) && get_device(dev))
> ^^^^^^^^^^^^^^^
> break;
> klist_iter_exit(&i);
> return dev;
>
> What that means is that when we're done with the struct device, we must
> drop that reference. Neither of_phy_connect() nor of_phy_attach() did
> this when phy_connect_direct() or phy_attach_direct() failed.
>
> With our previous patch, phy_connect_direct() and phy_attach_direct()
> take a new refcount on the phy device when successful, so we can drop
> our local reference immediatley after these functions, whether or not
> they succeeded.
>
> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Acked-by: Rob Herring <robh@xxxxxxxxxx>
> ---
> drivers/of/of_mdio.c | 27 +++++++++++++++++++++++----
> 1 file changed, 23 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
> index 1350fa25cdb0..a87a868fed64 100644
> --- a/drivers/of/of_mdio.c
> +++ b/drivers/of/of_mdio.c
> @@ -197,7 +197,8 @@ static int of_phy_match(struct device *dev, void *phy_np)
> * of_phy_find_device - Give a PHY node, find the phy_device
> * @phy_np: Pointer to the phy's device tree node
> *
> - * Returns a pointer to the phy_device.
> + * If successful, returns a pointer to the phy_device with the embedded
> + * struct device refcount incremented by one, or NULL on failure.
> */
> struct phy_device *of_phy_find_device(struct device_node *phy_np)
> {
> @@ -217,7 +218,9 @@ EXPORT_SYMBOL(of_phy_find_device);
> * @hndlr: Link state callback for the network device
> * @iface: PHY data interface type
> *
> - * Returns a pointer to the phy_device if successful. NULL otherwise
> + * If successful, returns a pointer to the phy_device with the embedded
> + * struct device refcount incremented by one, or NULL on failure. The
> + * refcount must be dropped by calling phy_disconnect() or phy_detach().
> */
> struct phy_device *of_phy_connect(struct net_device *dev,
> struct device_node *phy_np,
> @@ -225,13 +228,19 @@ struct phy_device *of_phy_connect(struct net_device *dev,
> phy_interface_t iface)
> {
> struct phy_device *phy = of_phy_find_device(phy_np);
> + int ret;
>
> if (!phy)
> return NULL;
>
> phy->dev_flags = flags;
>
> - return phy_connect_direct(dev, phy, hndlr, iface) ? NULL : phy;
> + ret = phy_connect_direct(dev, phy, hndlr, iface);
> +
> + /* refcount is held by phy_connect_direct() on success */
> + put_device(&phy->dev);
> +
> + return ret ? NULL : phy;
> }
> EXPORT_SYMBOL(of_phy_connect);
>
> @@ -241,17 +250,27 @@ EXPORT_SYMBOL(of_phy_connect);
> * @phy_np: Node pointer for the PHY
> * @flags: flags to pass to the PHY
> * @iface: PHY data interface type
> + *
> + * If successful, returns a pointer to the phy_device with the embedded
> + * struct device refcount incremented by one, or NULL on failure. The
> + * refcount must be dropped by calling phy_disconnect() or phy_detach().
> */
> struct phy_device *of_phy_attach(struct net_device *dev,
> struct device_node *phy_np, u32 flags,
> phy_interface_t iface)
> {
> struct phy_device *phy = of_phy_find_device(phy_np);
> + int ret;
>
> if (!phy)
> return NULL;
>
> - return phy_attach_direct(dev, phy, flags, iface) ? NULL : phy;
> + ret = phy_attach_direct(dev, phy, flags, iface);
> +
> + /* refcount is held by phy_attach_direct() on success */
> + put_device(&phy->dev);
> +
> + return ret ? NULL : phy;
> }
> EXPORT_SYMBOL(of_phy_attach);
>
> --
> 2.1.0
>
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