Message ID | E1ZfCJR-0004Rk-8M@rmk-PC.arm.linux.org.uk (mailing list archive) |
---|---|
State | Not Applicable |
Headers | show |
On Thu, Sep 24, 2015 at 2:36 PM, Russell King <rmk+kernel@arm.linux.org.uk> 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@arm.linux.org.uk> Acked-by: Rob Herring <robh@kernel.org> > --- > 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 >
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);
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@arm.linux.org.uk> --- drivers/of/of_mdio.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-)