* [PATCH] net: dsa: fix fixed-link-phy device leaks
@ 2016-11-16 14:47 Johan Hovold
2016-11-16 17:06 ` Florian Fainelli
0 siblings, 1 reply; 6+ messages in thread
From: Johan Hovold @ 2016-11-16 14:47 UTC (permalink / raw)
To: Andrew Lunn
Cc: Vivien Didelot, Florian Fainelli, David S. Miller, netdev,
linux-kernel, Johan Hovold
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);
}
}
}
--
2.7.3
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] net: dsa: fix fixed-link-phy device leaks
2016-11-16 14:47 [PATCH] net: dsa: fix fixed-link-phy device leaks Johan Hovold
@ 2016-11-16 17:06 ` Florian Fainelli
2016-11-16 17:11 ` Johan Hovold
0 siblings, 1 reply; 6+ messages in thread
From: Florian Fainelli @ 2016-11-16 17:06 UTC (permalink / raw)
To: Johan Hovold, Andrew Lunn
Cc: Vivien Didelot, David S. Miller, netdev, linux-kernel
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()?
--
Florian
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] net: dsa: fix fixed-link-phy device leaks
2016-11-16 17:06 ` Florian Fainelli
@ 2016-11-16 17:11 ` Johan Hovold
2016-11-16 18:14 ` Florian Fainelli
0 siblings, 1 reply; 6+ messages in thread
From: Johan Hovold @ 2016-11-16 17:11 UTC (permalink / raw)
To: Florian Fainelli
Cc: Johan Hovold, Andrew Lunn, Vivien Didelot, David S. Miller,
netdev, linux-kernel
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
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] net: dsa: fix fixed-link-phy device leaks
2016-11-16 17:11 ` Johan Hovold
@ 2016-11-16 18:14 ` Florian Fainelli
2016-11-17 9:52 ` Johan Hovold
0 siblings, 1 reply; 6+ messages in thread
From: Florian Fainelli @ 2016-11-16 18:14 UTC (permalink / raw)
To: Johan Hovold
Cc: Andrew Lunn, Vivien Didelot, David S. Miller, netdev, linux-kernel
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.
--
Florian
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] net: dsa: fix fixed-link-phy device leaks
2016-11-16 18:14 ` Florian Fainelli
@ 2016-11-17 9:52 ` Johan Hovold
2016-11-17 16:47 ` Johan Hovold
0 siblings, 1 reply; 6+ messages in thread
From: Johan Hovold @ 2016-11-17 9:52 UTC (permalink / raw)
To: Florian Fainelli
Cc: Johan Hovold, Andrew Lunn, Vivien Didelot, David S. Miller,
netdev, linux-kernel
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
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] net: dsa: fix fixed-link-phy device leaks
2016-11-17 9:52 ` Johan Hovold
@ 2016-11-17 16:47 ` Johan Hovold
0 siblings, 0 replies; 6+ messages in thread
From: Johan Hovold @ 2016-11-17 16:47 UTC (permalink / raw)
To: Florian Fainelli
Cc: Johan Hovold, Andrew Lunn, Vivien Didelot, David S. Miller,
netdev, linux-kernel
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
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-11-17 16:59 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2016-11-16 14:47 [PATCH] net: dsa: fix fixed-link-phy device leaks Johan Hovold
2016-11-16 17:06 ` Florian Fainelli
2016-11-16 17:11 ` Johan Hovold
2016-11-16 18:14 ` Florian Fainelli
2016-11-17 9:52 ` Johan Hovold
2016-11-17 16:47 ` Johan Hovold
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