[PATCH 0/3] remoteproc: core: Fixes for rproc cdev and add

[PATCH 0/3] remoteproc: core: Fixes for rproc cdev and add

[Siddharth Gupta]

This patch series contains stability fixes and error handling for remoteproc.

The changes included in this series do the following:
Patch 1: Fixes the creation of the rproc character device.
Patch 2: Validates rproc as the first step of rproc_add().
Patch 3: Adds error handling in rproc_add().

Siddharth Gupta (3):
  remoteproc: core: Move cdev add before device add
  remoteproc: core: Move validate before device add
  remoteproc: core: Cleanup device in case of failure

 drivers/remoteproc/remoteproc_core.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

-- 
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH 1/3] remoteproc: core: Move cdev add before device add

[Siddharth Gupta]

When cdev_add is called after device_add has been called there is no
way for the userspace to know about the addition of a cdev as cdev_add
itself doesn't trigger a uevent notification, or for the kernel to
know about the change to devt. This results in two problems:
 - mknod is never called for the cdev and hence no cdev appears on
   devtmpfs.
 - sysfs links to the new cdev are not established.

The cdev needs to be added and devt assigned before device_add() is
called in order for the relevant sysfs and devtmpfs entries to be
created and the uevent to be properly populated.

Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
---
 drivers/remoteproc/remoteproc_core.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 626a6b90f..562355a 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2316,6 +2316,11 @@ int rproc_add(struct rproc *rproc)
 	struct device *dev = &rproc->dev;
 	int ret;
 
+	/* add char device for this remoteproc */
+	ret = rproc_char_device_add(rproc);
+	if (ret < 0)
+		return ret;
+
 	ret = device_add(dev);
 	if (ret < 0)
 		return ret;
@@ -2329,11 +2334,6 @@ int rproc_add(struct rproc *rproc)
 	/* create debugfs entries */
 	rproc_create_debug_dir(rproc);
 
-	/* add char device for this remoteproc */
-	ret = rproc_char_device_add(rproc);
-	if (ret < 0)
-		return ret;
-
 	/* if rproc is marked always-on, request it to boot */
 	if (rproc->auto_boot) {
 		ret = rproc_trigger_auto_boot(rproc);
-- 
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH 1/3] remoteproc: core: Move cdev add before device add

[Bjorn Andersson]

On Mon 17 May 15:45 CDT 2021, Siddharth Gupta wrote:

> When cdev_add is called after device_add has been called there is no
> way for the userspace to know about the addition of a cdev as cdev_add
> itself doesn't trigger a uevent notification, or for the kernel to
> know about the change to devt. This results in two problems:
>  - mknod is never called for the cdev and hence no cdev appears on
>    devtmpfs.
>  - sysfs links to the new cdev are not established.
> 
> The cdev needs to be added and devt assigned before device_add() is
> called in order for the relevant sysfs and devtmpfs entries to be
> created and the uevent to be properly populated.
> 

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
> ---
>  drivers/remoteproc/remoteproc_core.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 626a6b90f..562355a 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -2316,6 +2316,11 @@ int rproc_add(struct rproc *rproc)
>  	struct device *dev = &rproc->dev;
>  	int ret;
>  
> +	/* add char device for this remoteproc */
> +	ret = rproc_char_device_add(rproc);
> +	if (ret < 0)
> +		return ret;
> +
>  	ret = device_add(dev);
>  	if (ret < 0)
>  		return ret;
> @@ -2329,11 +2334,6 @@ int rproc_add(struct rproc *rproc)
>  	/* create debugfs entries */
>  	rproc_create_debug_dir(rproc);
>  
> -	/* add char device for this remoteproc */
> -	ret = rproc_char_device_add(rproc);
> -	if (ret < 0)
> -		return ret;
> -
>  	/* if rproc is marked always-on, request it to boot */
>  	if (rproc->auto_boot) {
>  		ret = rproc_trigger_auto_boot(rproc);
> -- 
> Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

[PATCH 2/3] remoteproc: core: Move validate before device add

[Siddharth Gupta]

We can validate whether the remoteproc is correctly setup before
calling making the cdev_add and device_add calls. This saves us
the trouble of cleaning up later on.

Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
---
 drivers/remoteproc/remoteproc_core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 562355a..45d09bf 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2316,16 +2316,16 @@ int rproc_add(struct rproc *rproc)
 	struct device *dev = &rproc->dev;
 	int ret;
 
-	/* add char device for this remoteproc */
-	ret = rproc_char_device_add(rproc);
+	ret = rproc_validate(rproc);
 	if (ret < 0)
 		return ret;
 
-	ret = device_add(dev);
+	/* add char device for this remoteproc */
+	ret = rproc_char_device_add(rproc);
 	if (ret < 0)
 		return ret;
 
-	ret = rproc_validate(rproc);
+	ret = device_add(dev);
 	if (ret < 0)
 		return ret;
 
-- 
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH 2/3] remoteproc: core: Move validate before device add

[Bjorn Andersson]

On Mon 17 May 15:45 CDT 2021, Siddharth Gupta wrote:

> We can validate whether the remoteproc is correctly setup before
> calling making the cdev_add and device_add calls. This saves us
> the trouble of cleaning up later on.
> 

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

> Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
> ---
>  drivers/remoteproc/remoteproc_core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 562355a..45d09bf 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -2316,16 +2316,16 @@ int rproc_add(struct rproc *rproc)
>  	struct device *dev = &rproc->dev;
>  	int ret;
>  
> -	/* add char device for this remoteproc */
> -	ret = rproc_char_device_add(rproc);
> +	ret = rproc_validate(rproc);
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = device_add(dev);
> +	/* add char device for this remoteproc */
> +	ret = rproc_char_device_add(rproc);
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = rproc_validate(rproc);
> +	ret = device_add(dev);
>  	if (ret < 0)
>  		return ret;
>  
> -- 
> Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

[PATCH 3/3] remoteproc: core: Cleanup device in case of failure

[Siddharth Gupta]

When a failure occurs in rproc_add() it returns an error, but does
not cleanup after itself. This change adds the failure path in such
cases.

Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
---
 drivers/remoteproc/remoteproc_core.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 45d09bf..6f5fa81 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2326,8 +2326,10 @@ int rproc_add(struct rproc *rproc)
 		return ret;
 
 	ret = device_add(dev);
-	if (ret < 0)
-		return ret;
+	if (ret < 0) {
+		put_device(dev);
+		goto rproc_remove_cdev;
+	}
 
 	dev_info(dev, "%s is available\n", rproc->name);
 
@@ -2338,7 +2340,7 @@ int rproc_add(struct rproc *rproc)
 	if (rproc->auto_boot) {
 		ret = rproc_trigger_auto_boot(rproc);
 		if (ret < 0)
-			return ret;
+			goto rproc_remove_dev;
 	}
 
 	/* expose to rproc_get_by_phandle users */
@@ -2347,6 +2349,13 @@ int rproc_add(struct rproc *rproc)
 	mutex_unlock(&rproc_list_mutex);
 
 	return 0;
+
+rproc_remove_dev:
+	rproc_delete_debug_dir(rproc);
+	device_del(dev);
+rproc_remove_cdev:
+	rproc_char_device_remove(rproc);
+	return ret;
 }
 EXPORT_SYMBOL(rproc_add);
 
-- 
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH 3/3] remoteproc: core: Cleanup device in case of failure

[Bjorn Andersson]

On Mon 17 May 15:45 CDT 2021, Siddharth Gupta wrote:

> When a failure occurs in rproc_add() it returns an error, but does
> not cleanup after itself. This change adds the failure path in such
> cases.
> 
> Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
> ---
>  drivers/remoteproc/remoteproc_core.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 45d09bf..6f5fa81 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -2326,8 +2326,10 @@ int rproc_add(struct rproc *rproc)
>  		return ret;
>  
>  	ret = device_add(dev);
> -	if (ret < 0)
> -		return ret;
> +	if (ret < 0) {
> +		put_device(dev);
> +		goto rproc_remove_cdev;
> +	}
>  
>  	dev_info(dev, "%s is available\n", rproc->name);
>  
> @@ -2338,7 +2340,7 @@ int rproc_add(struct rproc *rproc)
>  	if (rproc->auto_boot) {
>  		ret = rproc_trigger_auto_boot(rproc);
>  		if (ret < 0)
> -			return ret;
> +			goto rproc_remove_dev;
>  	}
>  
>  	/* expose to rproc_get_by_phandle users */
> @@ -2347,6 +2349,13 @@ int rproc_add(struct rproc *rproc)
>  	mutex_unlock(&rproc_list_mutex);
>  
>  	return 0;
> +
> +rproc_remove_dev:
> +	rproc_delete_debug_dir(rproc);
> +	device_del(dev);
> +rproc_remove_cdev:
> +	rproc_char_device_remove(rproc);

I'm confused, shouldn't this function just do cdev_del()?
__unregister_chrdev() seems to do more than unroll what cdev_add()
did...

Apart from this, I think the patch looks good. Really nice to see you
tidy this up!

Regards,
Bjorn

> +	return ret;
>  }
>  EXPORT_SYMBOL(rproc_add);
>  
> -- 
> Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>