[v4,2/2] rpmsg: core: Add support to retrieve name extension
diff mbox series

Message ID 20200504215830.31394-3-mathieu.poirier@linaro.org
State New
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Series
  • pmsg: core: Add support for name extension
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Commit Message

Mathieu Poirier May 4, 2020, 9:58 p.m. UTC
After adding support for rpmsg device name extension, this patch
provides a function that returns the extension portion of an rpmsg
device name.  That way users of the name extension functionality don't
have to write the same boiler plate code to extract the information.

Suggested-by: Suman Anna <s-anna@ti.com>;
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/rpmsg/rpmsg_core.c | 92 ++++++++++++++++++++++++++++++++++++++
 include/linux/rpmsg.h      | 13 ++++++
 2 files changed, 105 insertions(+)

Comments

Arnaud POULIQUEN May 5, 2020, 8:07 a.m. UTC | #1
Hi Mathieu,



On 5/4/20 11:58 PM, Mathieu Poirier wrote:
> After adding support for rpmsg device name extension, this patch
> provides a function that returns the extension portion of an rpmsg
> device name.  That way users of the name extension functionality don't
> have to write the same boiler plate code to extract the information.
I do not test it yet,but LGTM.
I plan to use these patches for the rpmsg_tty.
Please find few remarks below.

> 
> Suggested-by: Suman Anna <s-anna@ti.com>;
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
>  drivers/rpmsg/rpmsg_core.c | 92 ++++++++++++++++++++++++++++++++++++++
>  include/linux/rpmsg.h      | 13 ++++++
>  2 files changed, 105 insertions(+)
> 
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index 5e01e8dede6b..dae87c0cb73d 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -439,6 +439,98 @@ static int rpmsg_dev_match(struct device *dev, struct device_driver *drv)
>  	return of_driver_match_device(dev, drv);
>  }
>  
> +/**
> + * rpmsg_device_get_name_extension() - get the name extension of a rpmsg device
> + * @rpdev: the rpmsg device to work with
> + * @skip: how many characters in the extension should be skipped over
> + *
> + * With function rpmsg_id_match() allowing for extension of the base driver name
> + * in order to differentiate services, this function returns the extension part
> + * of an rpmsg device name.  As such and with the following rpmsg driver device
> + * id table and rpmsg device names:
> + *
> + * static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = {
> + *      { .name = "rpmsg-client-sample" },
> + *      { },
> + * }
> + *
> + * rpdev1->id.name == "rpmsg-client-sample";
> + * rpdev2->id.name == "rpmsg-client-sample_instance0";
> + *
> + * Calling rpmsg_device_get_name_extension() will yields the following:
> + *
> + * rpmsg_device_get_name_extension(rpdev1, 0) == NULL;
> + * rpmsg_device_get_name_extension(rpdev2, 0) == "_instance0";
> + * rpmsg_device_get_name_extension(rpdev2, 1) == "instance0";
> + *
> + *
> + * Note: The name extension should be free'd using kfree_const().
> + *
> + * Return: the name extension if found, NULL if not found and an error
> + * code otherwise.
> + */
> +const char *rpmsg_device_get_name_extension(struct rpmsg_device *rpdev,
> +					    unsigned int skip)
> +{
> +	const char *drv_name, *dev_name, *extension;
> +	const struct rpmsg_device_id *ids;
> +	struct device *dev = &rpdev->dev;
> +	struct rpmsg_driver *rpdrv;
> +	bool match = false;
> +	unsigned int i;
> +
> +	if (!dev->driver)
> +		return ERR_PTR(-EINVAL);
> +
> +	rpdrv = to_rpmsg_driver(dev->driver);
> +
> +	/*
> +	 * No point in going further if the device and the driver don't
> +	 * have a name or a table to work with.
> +	 */
> +	if (!rpdev->id.name[0] || !rpdrv->id_table)
> +		return ERR_PTR(-EINVAL);
> +
> +	ids = rpdrv->id_table;
> +	dev_name = rpdev->id.name;
> +
> +	/*
> +	 * See if any name in the driver's table match the beginning
> +	 * of the rpmsg device's name.
> +	 */
> +	for (i = 0; ids[i].name[0]; i++) {
> +		drv_name = ids[i].name;
> +		if (strncmp(drv_name,
> +			    dev_name, strlen(drv_name)) == 0) {
> +			match = true;
> +			break;
> +		}
> +	}
> +
> +	if (!match)
> +		return NULL;
here i would return an error to differentiate unmatch and name without extension.
> +
> +	 /* No name extension to return if device and driver are the same */
> +	if (strlen(dev_name) == strlen(drv_name))
> +		return NULL;
> +
> +	/*
> +	 * Make sure we were not requested to skip past the end
> +	 * of the device name.
> +	 */
> +	if (strlen(drv_name) + skip >= strlen(dev_name))
> +		return ERR_PTR(-EINVAL);
> +
> +	/*
> +	 * Move past the base name published by the driver and
> +	 * skip any extra characters if needed.
> +	 */
> +	extension = dev_name + strlen(drv_name) + skip;
> +
> +	return kstrdup_const(extension, GFP_KERNEL);
what about just returning the extension pointer? 
rpdev->id.name should be valid until device is unregistered.

Regards
Arnaud

> +}
> +EXPORT_SYMBOL(rpmsg_device_get_name_extension);
> +
>  static int rpmsg_uevent(struct device *dev, struct kobj_uevent_env *env)
>  {
>  	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index 9fe156d1c018..9537b95ad30a 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -135,6 +135,9 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
>  __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
>  			poll_table *wait);
>  
> +const char *rpmsg_device_get_name_extension(struct rpmsg_device *dev,
> +					    unsigned int skip);
> +
>  #else
>  
>  static inline int register_rpmsg_device(struct rpmsg_device *dev)
> @@ -242,6 +245,16 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept,
>  	return 0;
>  }
>  
> +static inline
> +const char *rpmsg_device_get_name_extension(struct rpmsg_device *dev,
> +					    unsigned int skip)
> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +
> +	return NULL;
> +}
> +
>  #endif /* IS_ENABLED(CONFIG_RPMSG) */
>  
>  /* use a macro to avoid include chaining to get THIS_MODULE */
>
Mathieu Poirier May 5, 2020, 9:30 p.m. UTC | #2
On Tue, 5 May 2020 at 02:07, Arnaud POULIQUEN <arnaud.pouliquen@st.com> wrote:
>
> Hi Mathieu,
>
>
>
> On 5/4/20 11:58 PM, Mathieu Poirier wrote:
> > After adding support for rpmsg device name extension, this patch
> > provides a function that returns the extension portion of an rpmsg
> > device name.  That way users of the name extension functionality don't
> > have to write the same boiler plate code to extract the information.
> I do not test it yet,but LGTM.
> I plan to use these patches for the rpmsg_tty.
> Please find few remarks below.
>
> >
> > Suggested-by: Suman Anna <s-anna@ti.com>;
> > Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> > ---
> >  drivers/rpmsg/rpmsg_core.c | 92 ++++++++++++++++++++++++++++++++++++++
> >  include/linux/rpmsg.h      | 13 ++++++
> >  2 files changed, 105 insertions(+)
> >
> > diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> > index 5e01e8dede6b..dae87c0cb73d 100644
> > --- a/drivers/rpmsg/rpmsg_core.c
> > +++ b/drivers/rpmsg/rpmsg_core.c
> > @@ -439,6 +439,98 @@ static int rpmsg_dev_match(struct device *dev, struct device_driver *drv)
> >       return of_driver_match_device(dev, drv);
> >  }
> >
> > +/**
> > + * rpmsg_device_get_name_extension() - get the name extension of a rpmsg device
> > + * @rpdev: the rpmsg device to work with
> > + * @skip: how many characters in the extension should be skipped over
> > + *
> > + * With function rpmsg_id_match() allowing for extension of the base driver name
> > + * in order to differentiate services, this function returns the extension part
> > + * of an rpmsg device name.  As such and with the following rpmsg driver device
> > + * id table and rpmsg device names:
> > + *
> > + * static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = {
> > + *      { .name = "rpmsg-client-sample" },
> > + *      { },
> > + * }
> > + *
> > + * rpdev1->id.name == "rpmsg-client-sample";
> > + * rpdev2->id.name == "rpmsg-client-sample_instance0";
> > + *
> > + * Calling rpmsg_device_get_name_extension() will yields the following:
> > + *
> > + * rpmsg_device_get_name_extension(rpdev1, 0) == NULL;
> > + * rpmsg_device_get_name_extension(rpdev2, 0) == "_instance0";
> > + * rpmsg_device_get_name_extension(rpdev2, 1) == "instance0";
> > + *
> > + *
> > + * Note: The name extension should be free'd using kfree_const().
> > + *
> > + * Return: the name extension if found, NULL if not found and an error
> > + * code otherwise.
> > + */
> > +const char *rpmsg_device_get_name_extension(struct rpmsg_device *rpdev,
> > +                                         unsigned int skip)
> > +{
> > +     const char *drv_name, *dev_name, *extension;
> > +     const struct rpmsg_device_id *ids;
> > +     struct device *dev = &rpdev->dev;
> > +     struct rpmsg_driver *rpdrv;
> > +     bool match = false;
> > +     unsigned int i;
> > +
> > +     if (!dev->driver)
> > +             return ERR_PTR(-EINVAL);
> > +
> > +     rpdrv = to_rpmsg_driver(dev->driver);
> > +
> > +     /*
> > +      * No point in going further if the device and the driver don't
> > +      * have a name or a table to work with.
> > +      */
> > +     if (!rpdev->id.name[0] || !rpdrv->id_table)
> > +             return ERR_PTR(-EINVAL);
> > +
> > +     ids = rpdrv->id_table;
> > +     dev_name = rpdev->id.name;
> > +
> > +     /*
> > +      * See if any name in the driver's table match the beginning
> > +      * of the rpmsg device's name.
> > +      */
> > +     for (i = 0; ids[i].name[0]; i++) {
> > +             drv_name = ids[i].name;
> > +             if (strncmp(drv_name,
> > +                         dev_name, strlen(drv_name)) == 0) {
> > +                     match = true;
> > +                     break;
> > +             }
> > +     }
> > +
> > +     if (!match)
> > +             return NULL;
> here i would return an error to differentiate unmatch and name without extension.

That's a fair point.

> > +
> > +      /* No name extension to return if device and driver are the same */
> > +     if (strlen(dev_name) == strlen(drv_name))
> > +             return NULL;
> > +
> > +     /*
> > +      * Make sure we were not requested to skip past the end
> > +      * of the device name.
> > +      */
> > +     if (strlen(drv_name) + skip >= strlen(dev_name))
> > +             return ERR_PTR(-EINVAL);
> > +
> > +     /*
> > +      * Move past the base name published by the driver and
> > +      * skip any extra characters if needed.
> > +      */
> > +     extension = dev_name + strlen(drv_name) + skip;
> > +
> > +     return kstrdup_const(extension, GFP_KERNEL);
> what about just returning the extension pointer?
> rpdev->id.name should be valid until device is unregistered.

I grappled with that...  I didn't know all the scenarios people would
use this for and where the returned string would end up so I decided
to play it safe.  Does anyone else have an opinion on this?  Am I too
cautious?

>
> Regards
> Arnaud
>
> > +}
> > +EXPORT_SYMBOL(rpmsg_device_get_name_extension);
> > +
> >  static int rpmsg_uevent(struct device *dev, struct kobj_uevent_env *env)
> >  {
> >       struct rpmsg_device *rpdev = to_rpmsg_device(dev);
> > diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> > index 9fe156d1c018..9537b95ad30a 100644
> > --- a/include/linux/rpmsg.h
> > +++ b/include/linux/rpmsg.h
> > @@ -135,6 +135,9 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
> >  __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
> >                       poll_table *wait);
> >
> > +const char *rpmsg_device_get_name_extension(struct rpmsg_device *dev,
> > +                                         unsigned int skip);
> > +
> >  #else
> >
> >  static inline int register_rpmsg_device(struct rpmsg_device *dev)
> > @@ -242,6 +245,16 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept,
> >       return 0;
> >  }
> >
> > +static inline
> > +const char *rpmsg_device_get_name_extension(struct rpmsg_device *dev,
> > +                                         unsigned int skip)
> > +{
> > +     /* This shouldn't be possible */
> > +     WARN_ON(1);
> > +
> > +     return NULL;
> > +}
> > +
> >  #endif /* IS_ENABLED(CONFIG_RPMSG) */
> >
> >  /* use a macro to avoid include chaining to get THIS_MODULE */
> >

Patch
diff mbox series

diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index 5e01e8dede6b..dae87c0cb73d 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -439,6 +439,98 @@  static int rpmsg_dev_match(struct device *dev, struct device_driver *drv)
 	return of_driver_match_device(dev, drv);
 }
 
+/**
+ * rpmsg_device_get_name_extension() - get the name extension of a rpmsg device
+ * @rpdev: the rpmsg device to work with
+ * @skip: how many characters in the extension should be skipped over
+ *
+ * With function rpmsg_id_match() allowing for extension of the base driver name
+ * in order to differentiate services, this function returns the extension part
+ * of an rpmsg device name.  As such and with the following rpmsg driver device
+ * id table and rpmsg device names:
+ *
+ * static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = {
+ *      { .name = "rpmsg-client-sample" },
+ *      { },
+ * }
+ *
+ * rpdev1->id.name == "rpmsg-client-sample";
+ * rpdev2->id.name == "rpmsg-client-sample_instance0";
+ *
+ * Calling rpmsg_device_get_name_extension() will yields the following:
+ *
+ * rpmsg_device_get_name_extension(rpdev1, 0) == NULL;
+ * rpmsg_device_get_name_extension(rpdev2, 0) == "_instance0";
+ * rpmsg_device_get_name_extension(rpdev2, 1) == "instance0";
+ *
+ *
+ * Note: The name extension should be free'd using kfree_const().
+ *
+ * Return: the name extension if found, NULL if not found and an error
+ * code otherwise.
+ */
+const char *rpmsg_device_get_name_extension(struct rpmsg_device *rpdev,
+					    unsigned int skip)
+{
+	const char *drv_name, *dev_name, *extension;
+	const struct rpmsg_device_id *ids;
+	struct device *dev = &rpdev->dev;
+	struct rpmsg_driver *rpdrv;
+	bool match = false;
+	unsigned int i;
+
+	if (!dev->driver)
+		return ERR_PTR(-EINVAL);
+
+	rpdrv = to_rpmsg_driver(dev->driver);
+
+	/*
+	 * No point in going further if the device and the driver don't
+	 * have a name or a table to work with.
+	 */
+	if (!rpdev->id.name[0] || !rpdrv->id_table)
+		return ERR_PTR(-EINVAL);
+
+	ids = rpdrv->id_table;
+	dev_name = rpdev->id.name;
+
+	/*
+	 * See if any name in the driver's table match the beginning
+	 * of the rpmsg device's name.
+	 */
+	for (i = 0; ids[i].name[0]; i++) {
+		drv_name = ids[i].name;
+		if (strncmp(drv_name,
+			    dev_name, strlen(drv_name)) == 0) {
+			match = true;
+			break;
+		}
+	}
+
+	if (!match)
+		return NULL;
+
+	 /* No name extension to return if device and driver are the same */
+	if (strlen(dev_name) == strlen(drv_name))
+		return NULL;
+
+	/*
+	 * Make sure we were not requested to skip past the end
+	 * of the device name.
+	 */
+	if (strlen(drv_name) + skip >= strlen(dev_name))
+		return ERR_PTR(-EINVAL);
+
+	/*
+	 * Move past the base name published by the driver and
+	 * skip any extra characters if needed.
+	 */
+	extension = dev_name + strlen(drv_name) + skip;
+
+	return kstrdup_const(extension, GFP_KERNEL);
+}
+EXPORT_SYMBOL(rpmsg_device_get_name_extension);
+
 static int rpmsg_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
index 9fe156d1c018..9537b95ad30a 100644
--- a/include/linux/rpmsg.h
+++ b/include/linux/rpmsg.h
@@ -135,6 +135,9 @@  int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
 __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
 			poll_table *wait);
 
+const char *rpmsg_device_get_name_extension(struct rpmsg_device *dev,
+					    unsigned int skip);
+
 #else
 
 static inline int register_rpmsg_device(struct rpmsg_device *dev)
@@ -242,6 +245,16 @@  static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept,
 	return 0;
 }
 
+static inline
+const char *rpmsg_device_get_name_extension(struct rpmsg_device *dev,
+					    unsigned int skip)
+{
+	/* This shouldn't be possible */
+	WARN_ON(1);
+
+	return NULL;
+}
+
 #endif /* IS_ENABLED(CONFIG_RPMSG) */
 
 /* use a macro to avoid include chaining to get THIS_MODULE */