* [PATCH v3 1/8] Input: synaptics-rmi4: Use of_get_child_by_name() instead of of_find_node_by_name()
@ 2016-07-14 6:08 Andrew Duggan
2016-07-18 14:48 ` Benjamin Tissoires
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Duggan @ 2016-07-14 6:08 UTC (permalink / raw)
To: linux-input, linux-kernel
Cc: Andrew Duggan, Dmitry Torokhov, Linus Walleij, Jiri Kosina,
Benjamin Tissoires, Vincent Huang, Nick Dyer, Chris Healy
Calling of_find_node_by_name() assumes that the caller has incremented
the refcount of the of_node being passed in. Currently, the caller is
not incrementing the refcount of the of_node which results in the node
being prematurely freed when of_find_node_by_name() calls of_node_put()
on it. Instead use of_get_child_by_name() which does not call put on the
of_node.
Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
---
drivers/input/rmi4/rmi_bus.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
index b368b05..253df96 100644
--- a/drivers/input/rmi4/rmi_bus.c
+++ b/drivers/input/rmi4/rmi_bus.c
@@ -157,11 +157,11 @@ static int rmi_function_match(struct device *dev, struct device_driver *drv)
static void rmi_function_of_probe(struct rmi_function *fn)
{
char of_name[9];
+ struct device_node *node = fn->rmi_dev->xport->dev->of_node;
snprintf(of_name, sizeof(of_name), "rmi4-f%02x",
fn->fd.function_number);
- fn->dev.of_node = of_find_node_by_name(
- fn->rmi_dev->xport->dev->of_node, of_name);
+ fn->dev.of_node = of_get_child_by_name(node, of_name);
}
#else
static inline void rmi_function_of_probe(struct rmi_function *fn)
--
2.5.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v3 1/8] Input: synaptics-rmi4: Use of_get_child_by_name() instead of of_find_node_by_name()
2016-07-14 6:08 [PATCH v3 1/8] Input: synaptics-rmi4: Use of_get_child_by_name() instead of of_find_node_by_name() Andrew Duggan
@ 2016-07-18 14:48 ` Benjamin Tissoires
2016-07-18 23:13 ` Andrew Duggan
0 siblings, 1 reply; 4+ messages in thread
From: Benjamin Tissoires @ 2016-07-18 14:48 UTC (permalink / raw)
To: Andrew Duggan
Cc: linux-input, linux-kernel, Dmitry Torokhov, Linus Walleij,
Jiri Kosina, Vincent Huang, Nick Dyer, Chris Healy
On Jul 13 2016 or thereabouts, Andrew Duggan wrote:
> Calling of_find_node_by_name() assumes that the caller has incremented
> the refcount of the of_node being passed in. Currently, the caller is
> not incrementing the refcount of the of_node which results in the node
> being prematurely freed when of_find_node_by_name() calls of_node_put()
> on it. Instead use of_get_child_by_name() which does not call put on the
> of_node.
There are 2 other differences in using of_get_child_by_name() in place
of of_find_node_by_name(). One is that now we are following the OF tree
while the spinlock is not held. I think it's fine in our case. The
other difference is that the returned of_node has not been called
of_node_get() on it. I am not 100% sure, but I think it might be good to
call of_node_get() on the of node here, and in remove call
of_node_put(), just to be sure we don't use the of_node while it has
been freed.
Cheers,
Benjamin
>
> Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
> ---
> drivers/input/rmi4/rmi_bus.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
> index b368b05..253df96 100644
> --- a/drivers/input/rmi4/rmi_bus.c
> +++ b/drivers/input/rmi4/rmi_bus.c
> @@ -157,11 +157,11 @@ static int rmi_function_match(struct device *dev, struct device_driver *drv)
> static void rmi_function_of_probe(struct rmi_function *fn)
> {
> char of_name[9];
> + struct device_node *node = fn->rmi_dev->xport->dev->of_node;
>
> snprintf(of_name, sizeof(of_name), "rmi4-f%02x",
> fn->fd.function_number);
> - fn->dev.of_node = of_find_node_by_name(
> - fn->rmi_dev->xport->dev->of_node, of_name);
> + fn->dev.of_node = of_get_child_by_name(node, of_name);
> }
> #else
> static inline void rmi_function_of_probe(struct rmi_function *fn)
> --
> 2.5.0
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3 1/8] Input: synaptics-rmi4: Use of_get_child_by_name() instead of of_find_node_by_name()
2016-07-18 14:48 ` Benjamin Tissoires
@ 2016-07-18 23:13 ` Andrew Duggan
2016-07-19 9:37 ` Benjamin Tissoires
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Duggan @ 2016-07-18 23:13 UTC (permalink / raw)
To: Benjamin Tissoires
Cc: linux-input, linux-kernel, Dmitry Torokhov, Linus Walleij,
Jiri Kosina, Vincent Huang, Nick Dyer, Chris Healy
On 07/18/2016 07:48 AM, Benjamin Tissoires wrote:
> On Jul 13 2016 or thereabouts, Andrew Duggan wrote:
>> Calling of_find_node_by_name() assumes that the caller has incremented
>> the refcount of the of_node being passed in. Currently, the caller is
>> not incrementing the refcount of the of_node which results in the node
>> being prematurely freed when of_find_node_by_name() calls of_node_put()
>> on it. Instead use of_get_child_by_name() which does not call put on the
>> of_node.
> There are 2 other differences in using of_get_child_by_name() in place
> of of_find_node_by_name(). One is that now we are following the OF tree
> while the spinlock is not held. I think it's fine in our case. The
> other difference is that the returned of_node has not been called
> of_node_get() on it. I am not 100% sure, but I think it might be good to
> call of_node_get() on the of node here, and in remove call
> of_node_put(), just to be sure we don't use the of_node while it has
> been freed.
The comment for of_get_child_by_name() says that it returns an of_node
with the refcount incremented (drivers/of/base.c:717). Also, that the
caller needs to call of_node_put() when finished with it. I take that to
mean that the of_node_get() has been done for me by
of_get_child_by_name(). Then rmi_unregister_function() calls
of_node_put() when unregistered the function device undoing
of_get_child_by_name()'s increment of the refcount.
Unless I am missing something I think the current implementation is
correct. Hopefully, it is since this patch has already landed in Linus's
tree.
Andrew
>
> Cheers,
> Benjamin
>
>> Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
>> ---
>> drivers/input/rmi4/rmi_bus.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
>> index b368b05..253df96 100644
>> --- a/drivers/input/rmi4/rmi_bus.c
>> +++ b/drivers/input/rmi4/rmi_bus.c
>> @@ -157,11 +157,11 @@ static int rmi_function_match(struct device *dev, struct device_driver *drv)
>> static void rmi_function_of_probe(struct rmi_function *fn)
>> {
>> char of_name[9];
>> + struct device_node *node = fn->rmi_dev->xport->dev->of_node;
>>
>> snprintf(of_name, sizeof(of_name), "rmi4-f%02x",
>> fn->fd.function_number);
>> - fn->dev.of_node = of_find_node_by_name(
>> - fn->rmi_dev->xport->dev->of_node, of_name);
>> + fn->dev.of_node = of_get_child_by_name(node, of_name);
>> }
>> #else
>> static inline void rmi_function_of_probe(struct rmi_function *fn)
>> --
>> 2.5.0
>>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3 1/8] Input: synaptics-rmi4: Use of_get_child_by_name() instead of of_find_node_by_name()
2016-07-18 23:13 ` Andrew Duggan
@ 2016-07-19 9:37 ` Benjamin Tissoires
0 siblings, 0 replies; 4+ messages in thread
From: Benjamin Tissoires @ 2016-07-19 9:37 UTC (permalink / raw)
To: Andrew Duggan
Cc: linux-input, linux-kernel, Dmitry Torokhov, Linus Walleij,
Jiri Kosina, Vincent Huang, Nick Dyer, Chris Healy
On Jul 18 2016 or thereabouts, Andrew Duggan wrote:
> On 07/18/2016 07:48 AM, Benjamin Tissoires wrote:
> >On Jul 13 2016 or thereabouts, Andrew Duggan wrote:
> >>Calling of_find_node_by_name() assumes that the caller has incremented
> >>the refcount of the of_node being passed in. Currently, the caller is
> >>not incrementing the refcount of the of_node which results in the node
> >>being prematurely freed when of_find_node_by_name() calls of_node_put()
> >>on it. Instead use of_get_child_by_name() which does not call put on the
> >>of_node.
> >There are 2 other differences in using of_get_child_by_name() in place
> >of of_find_node_by_name(). One is that now we are following the OF tree
> >while the spinlock is not held. I think it's fine in our case. The
> >other difference is that the returned of_node has not been called
> >of_node_get() on it. I am not 100% sure, but I think it might be good to
> >call of_node_get() on the of node here, and in remove call
> >of_node_put(), just to be sure we don't use the of_node while it has
> >been freed.
>
> The comment for of_get_child_by_name() says that it returns an of_node with
> the refcount incremented (drivers/of/base.c:717). Also, that the caller
> needs to call of_node_put() when finished with it. I take that to mean that
> the of_node_get() has been done for me by of_get_child_by_name(). Then
> rmi_unregister_function() calls of_node_put() when unregistered the function
> device undoing of_get_child_by_name()'s increment of the refcount.
>
> Unless I am missing something I think the current implementation is correct.
> Hopefully, it is since this patch has already landed in Linus's tree.
Oh, then OK. Sorry for coming late in the party then :)
Cheers,
Benjamin
>
> Andrew
>
> >
> >Cheers,
> >Benjamin
> >
> >>Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
> >>---
> >> drivers/input/rmi4/rmi_bus.c | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >>diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
> >>index b368b05..253df96 100644
> >>--- a/drivers/input/rmi4/rmi_bus.c
> >>+++ b/drivers/input/rmi4/rmi_bus.c
> >>@@ -157,11 +157,11 @@ static int rmi_function_match(struct device *dev, struct device_driver *drv)
> >> static void rmi_function_of_probe(struct rmi_function *fn)
> >> {
> >> char of_name[9];
> >>+ struct device_node *node = fn->rmi_dev->xport->dev->of_node;
> >> snprintf(of_name, sizeof(of_name), "rmi4-f%02x",
> >> fn->fd.function_number);
> >>- fn->dev.of_node = of_find_node_by_name(
> >>- fn->rmi_dev->xport->dev->of_node, of_name);
> >>+ fn->dev.of_node = of_get_child_by_name(node, of_name);
> >> }
> >> #else
> >> static inline void rmi_function_of_probe(struct rmi_function *fn)
> >>--
> >>2.5.0
> >>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-07-19 9:37 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-07-14 6:08 [PATCH v3 1/8] Input: synaptics-rmi4: Use of_get_child_by_name() instead of of_find_node_by_name() Andrew Duggan
2016-07-18 14:48 ` Benjamin Tissoires
2016-07-18 23:13 ` Andrew Duggan
2016-07-19 9:37 ` Benjamin Tissoires
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).