Merge branch 'phy-mdio-refcnt'
Russell King says: ==================== Phy, mdiobus, and netdev struct device fixes The third version of this series fixes the build error which David identified, and drops the broken changes for the Cavium Thunger BGX ethernet driver as this driver requires some complex changes to resolve the leakage - and this is best done by people who can test the driver. Compared to v2, the only patch which has changed is patch 6 "net: fix phy refcounting in a bunch of drivers" I _think_ I've been able to build-test all the drivers touched by that patch to some degree now, though several of them needed the Kconfig hacked to allow it (not all had || COMPILE_TEST clause on their dependencies.) Previous cover letters below: This is the second version of the series, with the comments David had on the first patch fixed up. Original series description with updated diffstat below. While looking at the DSA code, I noticed we have a of_find_net_device_by_node(), and it looks like users of that are similarly buggy - it looks like net/dsa/dsa.c is the only user. Fix that too. Hi, While looking at the phy code, I identified a number of weaknesses where refcounting on device structures was being leaked, where modules could be removed while in-use, and where the fixed-phy could end up having unintended consequences caused by incorrect calls to fixed_phy_update_state(). This patch series resolves those issues, some of which were discovered with testing on an Armada 388 board. Not all patches are fully tested, particularly the one which touches several network drivers. When resolving the struct device refcounting problems, several different solutions were considered before settling on the implementation here - one of the considerations was to avoid touching many network drivers. The solution here is: phy_attach*() - takes a refcount phy_detach*() - drops the phy_attach refcount Provided drivers always attach and detach their phys, which they should already be doing, this should change nothing, even if they leak a refcount. of_phy_find_device() and of_* functions which use that take a refcount. Arrange for this refcount to be dropped once the phy is attached. This is the reason why the previous change is important - we can't drop this refcount taken by of_phy_find_device() until something else holds a reference on the device. This resolves the leaked refcount caused by using of_phy_connect() or of_phy_attach(). Even without the above changes, these drivers are leaking by calling of_phy_find_device(). These drivers are addressed by adding the appropriate release of that refcount. The mdiobus code also suffered from the same kind of leak, but thankfully this only happened in one place - the mdio-mux code. I also found that the try_module_get() in the phy layer code was utterly useless: phydev->dev.driver was guaranteed to always be NULL, so try_module_get() was always being called with a NULL argument. I proved this with my SFP code, which declares its own MDIO bus - the module use count was never incremented irrespective of how I set the MDIO bus up. This allowed the MDIO bus code to be removed from the kernel while there were still PHYs attached to it. One other bug was discovered: while using in-band-status with mvneta, it was found that if a real phy is attached with in-band-status enabled, and another ethernet interface is using the fixed-phy infrastructure, the interface using the fixed-phy infrastructure is configured according to the other interface using the in-band-status - which is caused by the fixed-phy code not verifying that the phy_device passed in is actually a fixed-phy device, rather than a real MDIO phy. Lastly, having mdio_bus reversing phy_device_register() internals seems like a layering violation - it's trivial to move that code to the phy device layer. ==================== Tested-by:Florian Fainelli <f.fainelli@gmail.com> Reviewed-by:
David S. Miller <davem@davemloft.net>
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