Messages in this thread | | | Date | Wed, 16 Nov 2016 18:11:45 +0100 | From | Johan Hovold <> | Subject | Re: [PATCH] net: dsa: fix fixed-link-phy device leaks |
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On Wed, Nov 16, 2016 at 09:06:26AM -0800, Florian Fainelli wrote: > On 11/16/2016 06:47 AM, Johan Hovold wrote: > > Make sure to drop the reference taken by of_phy_find_device() when > > registering and deregistering the fixed-link PHY-device. > > > > Note that we need to put both references held at deregistration. > > > > Fixes: 39b0c705195e ("net: dsa: Allow configuration of CPU & DSA port > > speeds/duplex") > > Signed-off-by: Johan Hovold <johan@kernel.org> > > --- > > > > Hi, > > > > This is one has been compile tested only, but fixes a couple of leaks > > similar to one that was found in the cpsw driver for which I just posted > > a patch. > > > > It turns out all drivers but DSA fail to deregister the fixed-link PHYs > > registered by of_phy_register_fixed_link(). Due to the way this > > interface was designed, deregistering such a PHY is a bit cumbersome and > > looks like it would benefit from a common helper. > > > > However, perhaps the interface should instead be changed so that the PHY > > device is returned so that drivers do not need to use > > of_phy_find_device() when they need to access properties of the fixed > > link (e.g. as in dsu_cpu_dsa_setup below). > > > > Thoughts? > > > > Thanks, > > Johan > > > > > > net/dsa/dsa.c | 8 +++++++- > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c > > index a6902c1e2f28..798a6a776a5f 100644 > > --- a/net/dsa/dsa.c > > +++ b/net/dsa/dsa.c > > @@ -233,6 +233,8 @@ int dsa_cpu_dsa_setup(struct dsa_switch *ds, struct device *dev, > > genphy_read_status(phydev); > > if (ds->ops->adjust_link) > > ds->ops->adjust_link(ds, port, phydev); > > + > > + phy_device_free(phydev); /* of_phy_find_device */ > > } > > > > return 0; > > @@ -509,8 +511,12 @@ void dsa_cpu_dsa_destroy(struct device_node *port_dn) > > if (of_phy_is_fixed_link(port_dn)) { > > phydev = of_phy_find_device(port_dn); > > if (phydev) { > > - phy_device_free(phydev); > > fixed_phy_unregister(phydev); > > + /* Put references taken by of_phy_find_device() and > > + * of_phy_register_fixed_link(). > > + */ > > + phy_device_free(phydev); > > + phy_device_free(phydev); > > Double free, this looks bogus here. Actually would not this mean a > triple free since you already free in dsa_cpu_dsa_setup() which is > paired with dsa_cpu_dsa_destroy()?
The naming of phy_device_free() is unfortunate when it's really a put():
void phy_device_free(struct phy_device *phydev) { put_device(&phydev->mdio.dev); }
which may need to be called multiple times, specifically after a call to of_phy_find_device() which takes another reference.
With this patch the refcounts are properly balanced.
Johan
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