| Message ID | 1479307664-32428-1-git-send-email-johan@kernel.org |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
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()?
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
On 11/16/2016 09:11 AM, Johan Hovold wrote: > 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); > } Indeed, should have looked a little harder. > > 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. The intent of your patch is good, but it still feels like having to double imbalance the refcount is symptomatic of a larger issue here, it does not seem like having several refcounts are necessary, so we may really want to rework the API.
On Wed, Nov 16, 2016 at 10:14:10AM -0800, Florian Fainelli wrote: > On 11/16/2016 09:11 AM, Johan Hovold wrote: > > 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); > > } > > Indeed, should have looked a little harder. > > > > > 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. > > The intent of your patch is good, but it still feels like having to > double imbalance the refcount is symptomatic of a larger issue here, it > does not seem like having several refcounts are necessary, so we may > really want to rework the API. I'll cook something up for -next, but how about using put_device(&phydev->mdio.dev) for the reference taken by of_phy_find_device() (as some driver already do) to fix the immediate leaks? Then deregistration would look like: phydev = of_phy_find_device(port_dn); if (phydev) { - phy_device_free(phydev); fixed_phy_unregister(phydev); + put_device(&phydev->mdio.dev) + phy_device_free(phydev); Thanks, Johan
On Thu, Nov 17, 2016 at 10:52:25AM +0100, Johan Hovold wrote: > On Wed, Nov 16, 2016 at 10:14:10AM -0800, Florian Fainelli wrote: > > On 11/16/2016 09:11 AM, Johan Hovold wrote: > > > 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); > > > } > > > > Indeed, should have looked a little harder. > > > > > > > > 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. > > > > The intent of your patch is good, but it still feels like having to > > double imbalance the refcount is symptomatic of a larger issue here, it > > does not seem like having several refcounts are necessary, so we may > > really want to rework the API. > > I'll cook something up for -next, but how about using > > put_device(&phydev->mdio.dev) > > for the reference taken by of_phy_find_device() (as some driver > already do) to fix the immediate leaks? > > Then deregistration would look like: > > phydev = of_phy_find_device(port_dn); > if (phydev) { > - phy_device_free(phydev); > fixed_phy_unregister(phydev); > + put_device(&phydev->mdio.dev) > + phy_device_free(phydev); On second thought, I suggest just renaming the phy_device_free() as phy_device_put() to reflect what it really does these days. There can never be a guarantee that the phy is freed on a call to phy_device_free() anyway. The OF interface can still be modified to return a pointer later. Johan
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); } } }
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(-)