[PATCH] soc: ti: knav_dma: remove debugfs file on teardown

[PATCH] soc: ti: knav_dma: remove debugfs file on teardown

[Pengpeng Hou]

knav_dma_probe() creates the global knav_dma debugfs file whose show
callback walks the global kdev list. knav_dma_remove() tears down the DMA
instances and runtime PM but leaves that debugfs file and global ready
state behind.

Save the debugfs dentry, remove it before destroying the DMA state, and
clear the global ready pointer state during remove.

Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
 drivers/soc/ti/knav_dma.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/ti/knav_dma.c b/drivers/soc/ti/knav_dma.c
index e5f5e3142fc4..9277c525ac21 100644
--- a/drivers/soc/ti/knav_dma.c
+++ b/drivers/soc/ti/knav_dma.c
@@ -125,6 +125,7 @@ struct knav_dma_chan {
 			ch->channel : ch->flow)
 
 static struct knav_dma_pool_device *kdev;
+static struct dentry *knav_dma_debugfs;
 
 static bool device_ready;
 bool knav_dma_device_ready(void)
@@ -740,8 +741,9 @@ static int knav_dma_probe(struct platform_device *pdev)
 		goto err_put_sync;
 	}
 
-	debugfs_create_file("knav_dma", S_IFREG | S_IRUGO, NULL, NULL,
-			    &knav_dma_debug_fops);
+	knav_dma_debugfs = debugfs_create_file("knav_dma", 0444,
+					       NULL, NULL,
+					       &knav_dma_debug_fops);
 
 	device_ready = true;
 	return ret;
@@ -758,6 +760,10 @@ static void knav_dma_remove(struct platform_device *pdev)
 {
 	struct knav_dma_device *dma;
 
+	device_ready = false;
+	debugfs_remove(knav_dma_debugfs);
+	knav_dma_debugfs = NULL;
+
 	list_for_each_entry(dma, &kdev->list, list) {
 		if (atomic_dec_return(&dma->ref_count) == 0)
 			knav_dma_hw_destroy(dma);
@@ -765,6 +771,7 @@ static void knav_dma_remove(struct platform_device *pdev)
 
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
+	kdev = NULL;
 }
 
 static struct of_device_id of_match[] = {
-- 
2.50.1 (Apple Git-155)

Re: [PATCH] soc: ti: knav_dma: remove debugfs file on teardown

[Nishanth Menon]

On 17:12-20260615, Pengpeng Hou wrote:
> knav_dma_probe() creates the global knav_dma debugfs file whose show
> callback walks the global kdev list. knav_dma_remove() tears down the DMA
> instances and runtime PM but leaves that debugfs file and global ready
> state behind.
> 
> Save the debugfs dentry, remove it before destroying the DMA state, and
> clear the global ready pointer state during remove.
> 
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
>  drivers/soc/ti/knav_dma.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soc/ti/knav_dma.c b/drivers/soc/ti/knav_dma.c
> index e5f5e3142fc4..9277c525ac21 100644
> --- a/drivers/soc/ti/knav_dma.c
> +++ b/drivers/soc/ti/knav_dma.c
> @@ -125,6 +125,7 @@ struct knav_dma_chan {
>  			ch->channel : ch->flow)
>  
>  static struct knav_dma_pool_device *kdev;
> +static struct dentry *knav_dma_debugfs;

Similar comment as previous patch to consider moving this to
knav_dma_pool_device.

>  
>  static bool device_ready;
>  bool knav_dma_device_ready(void)
> @@ -740,8 +741,9 @@ static int knav_dma_probe(struct platform_device *pdev)
>  		goto err_put_sync;
>  	}
>  
> -	debugfs_create_file("knav_dma", S_IFREG | S_IRUGO, NULL, NULL,
> -			    &knav_dma_debug_fops);
> +	knav_dma_debugfs = debugfs_create_file("knav_dma", 0444,

0444 is worth mentioning in the commit message.

> +					       NULL, NULL,
> +					       &knav_dma_debug_fops);
>  
>  	device_ready = true;
>  	return ret;
> @@ -758,6 +760,10 @@ static void knav_dma_remove(struct platform_device *pdev)
>  {
>  	struct knav_dma_device *dma;
>  
> +	device_ready = false;
> +	debugfs_remove(knav_dma_debugfs);
> +	knav_dma_debugfs = NULL;
> +
>  	list_for_each_entry(dma, &kdev->list, list) {
>  		if (atomic_dec_return(&dma->ref_count) == 0)
>  			knav_dma_hw_destroy(dma);
> @@ -765,6 +771,7 @@ static void knav_dma_remove(struct platform_device *pdev)
>  
>  	pm_runtime_put_sync(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
> +	kdev = NULL;

Also worth stating in the commit message.

>  }
>  
>  static struct of_device_id of_match[] = {
> -- 
> 2.50.1 (Apple Git-155)
> 
> 

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D
https://ti.com/opensource

Re: [PATCH] soc: ti: knav_dma: remove debugfs file on teardown

[Hari Prasath]

Hello,

On 15/06/26 2:42 pm, Pengpeng Hou wrote:
> knav_dma_probe() creates the global knav_dma debugfs file whose show
> callback walks the global kdev list. knav_dma_remove() tears down the DMA
> instances and runtime PM but leaves that debugfs file and global ready
> state behind.
> 
> Save the debugfs dentry, remove it before destroying the DMA state, and
> clear the global ready pointer state during remove.
> 
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
>   drivers/soc/ti/knav_dma.c | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soc/ti/knav_dma.c b/drivers/soc/ti/knav_dma.c
> index e5f5e3142fc4..9277c525ac21 100644
> --- a/drivers/soc/ti/knav_dma.c
> +++ b/drivers/soc/ti/knav_dma.c
> @@ -125,6 +125,7 @@ struct knav_dma_chan {
>   			ch->channel : ch->flow)
>   
>   static struct knav_dma_pool_device *kdev;
> +static struct dentry *knav_dma_debugfs;
>   
>   static bool device_ready;
>   bool knav_dma_device_ready(void)
> @@ -740,8 +741,9 @@ static int knav_dma_probe(struct platform_device *pdev)
>   		goto err_put_sync;
>   	}
>   
> -	debugfs_create_file("knav_dma", S_IFREG | S_IRUGO, NULL, NULL,
> -			    &knav_dma_debug_fops);
> +	knav_dma_debugfs = debugfs_create_file("knav_dma", 0444,
> +					       NULL, NULL,
> +					       &knav_dma_debug_fops);
>   
>   	device_ready = true;
>   	return ret;
> @@ -758,6 +760,10 @@ static void knav_dma_remove(struct platform_device *pdev)
>   {
>   	struct knav_dma_device *dma;
>   
> +	device_ready = false;
> +	debugfs_remove(knav_dma_debugfs);

Does this handle the case where a process already has the debugfs file 
open? A concurrent read() from the userspace could still potentially 
reach knav_dma_debug_show() and access kdev while it's being torn down
below. Pls check and add necessary protection around kdev access.

Regards,
Hari 


> +	knav_dma_debugfs = NULL;
> +
>   	list_for_each_entry(dma, &kdev->list, list) {
>   		if (atomic_dec_return(&dma->ref_count) == 0)
>   			knav_dma_hw_destroy(dma);
> @@ -765,6 +771,7 @@ static void knav_dma_remove(struct platform_device *pdev)
>   
>   	pm_runtime_put_sync(&pdev->dev);
>   	pm_runtime_disable(&pdev->dev);
> +	kdev = NULL;
>   }
>   
>   static struct of_device_id of_match[] = {