Linux Virtualization - Dec 2017 - [PATCH] virtio_mmio: add cleanup for virtio_mmio_probe

cleanup all resource allocated by virtio_mmio_probe.

Signed-off-by: weiping zhang <zhangweiping at didichuxing.com>
---
 drivers/virtio/virtio_mmio.c | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 74dc717..3fd0e66 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -513,8 +513,10 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 		return -EBUSY;
 
 	vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
-	if (!vm_dev)
-		return  -ENOMEM;
+	if (!vm_dev) {
+		rc =  -ENOMEM;
+		goto free_mem;
+	}
 
 	vm_dev->vdev.dev.parent = &pdev->dev;
 	vm_dev->vdev.dev.release = virtio_mmio_release_dev_empty;
@@ -524,14 +526,17 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	spin_lock_init(&vm_dev->lock);
 
 	vm_dev->base = devm_ioremap(&pdev->dev, mem->start,
resource_size(mem));
-	if (vm_dev->base == NULL)
-		return -EFAULT;
+	if (vm_dev->base == NULL) {
+		rc = -EFAULT;
+		goto free_vmdev;
+	}
 
 	/* Check magic value */
 	magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
 	if (magic != ('v' | 'i' << 8 | 'r' << 16 |
't' << 24)) {
 		dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
-		return -ENODEV;
+		rc = -ENODEV;
+		goto unmap;
 	}
 
 	/* Check device version */
@@ -539,7 +544,8 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	if (vm_dev->version < 1 || vm_dev->version > 2) {
 		dev_err(&pdev->dev, "Version %ld not supported!\n",
 				vm_dev->version);
-		return -ENXIO;
+		rc = -ENXIO;
+		goto unmap;
 	}
 
 	vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
@@ -548,7 +554,8 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 		 * virtio-mmio device with an ID 0 is a (dummy) placeholder
 		 * with no function. End probing now with no error reported.
 		 */
-		return -ENODEV;
+		rc = -ENODEV;
+		goto unmap;
 	}
 	vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
 
@@ -573,7 +580,18 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, vm_dev);
 
-	return register_virtio_device(&vm_dev->vdev);
+	rc = register_virtio_device(&vm_dev->vdev);
+	if (rc)
+		goto unmap;
+	return 0;
+unmap:
+	iounmap(vm_dev->base);
+free_mem:
+	devm_release_mem_region(&pdev->dev, mem->start,
+			resource_size(mem));
+free_vmdev:
+	devm_kfree(&pdev->dev, vm_dev);
+	return rc;
 }
 
 static int virtio_mmio_remove(struct platform_device *pdev)
-- 
2.9.4

On Sat, 2 Dec 2017 01:51:40 +0800
weiping zhang <zwp10758 at gmail.com> wrote:
> cleanup all resource allocated by virtio_mmio_probe.
> 
> Signed-off-by: weiping zhang <zhangweiping at didichuxing.com>
> ---
>  drivers/virtio/virtio_mmio.c | 34 ++++++++++++++++++++++++++--------
>  1 file changed, 26 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index 74dc717..3fd0e66 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/drivers/virtio/virtio_mmio.c
> @@ -513,8 +513,10 @@ static int virtio_mmio_probe(struct platform_device
*pdev)
>  		return -EBUSY;
>  
>  	vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
> -	if (!vm_dev)
> -		return  -ENOMEM;
> +	if (!vm_dev) {
> +		rc =  -ENOMEM;
Touching this would be a good time to remove the extra space in front
of the -ENOMEM :)
> +		goto free_mem;
> +	}
>  
>  	vm_dev->vdev.dev.parent = &pdev->dev;
>  	vm_dev->vdev.dev.release = virtio_mmio_release_dev_empty;
(...)
> @@ -573,7 +580,18 @@ static int virtio_mmio_probe(struct platform_device
*pdev)
>  
>  	platform_set_drvdata(pdev, vm_dev);
>  
> -	return register_virtio_device(&vm_dev->vdev);
> +	rc = register_virtio_device(&vm_dev->vdev);
> +	if (rc)
> +		goto unmap;
> +	return 0;
> +unmap:
> +	iounmap(vm_dev->base);
> +free_mem:
> +	devm_release_mem_region(&pdev->dev, mem->start,
> +			resource_size(mem));
> +free_vmdev:
> +	devm_kfree(&pdev->dev, vm_dev);
I think this is problematic as vm_dev embeds a struct device (via
embedding a struct virtio_device). I think the right way to do this is
- call this only if register_virtio_device() has not been called
- put the devm_kfree() into the ->release callback for the
  virtio_device (IOW, replace virtio_mmio_release_dev_empty() with a
  function that calls this)
- do a put_device() if register_virtio_device() failed

I might be missing some interaction between the usual driver model
handling and devm resources, though.
> +	return rc;
>  }
>  
>  static int virtio_mmio_remove(struct platform_device *pdev)

2017-12-04 18:24 GMT+08:00 Cornelia Huck <cohuck at
redhat.com>:
> On Sat, 2 Dec 2017 01:51:40 +0800
> weiping zhang <zwp10758 at gmail.com> wrote:
>
>> cleanup all resource allocated by virtio_mmio_probe.
>>
>> Signed-off-by: weiping zhang <zhangweiping at didichuxing.com>
>> ---
>>  drivers/virtio/virtio_mmio.c | 34 ++++++++++++++++++++++++++--------
>>  1 file changed, 26 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/virtio/virtio_mmio.c
b/drivers/virtio/virtio_mmio.c
>> index 74dc717..3fd0e66 100644
>> --- a/drivers/virtio/virtio_mmio.c
>> +++ b/drivers/virtio/virtio_mmio.c
>> @@ -513,8 +513,10 @@ static int virtio_mmio_probe(struct
platform_device *pdev)
>>               return -EBUSY;
>>
>>       vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev),
GFP_KERNEL);
>> -     if (!vm_dev)
>> -             return  -ENOMEM;
>> +     if (!vm_dev) {
>> +             rc =  -ENOMEM;
>
> Touching this would be a good time to remove the extra space in front
> of the -ENOMEM :)
Thanks, I fix this at V2.
>
>> +             goto free_mem;
>> +     }
>>
>>       vm_dev->vdev.dev.parent = &pdev->dev;
>>       vm_dev->vdev.dev.release = virtio_mmio_release_dev_empty;
>
> (...)
>
>> @@ -573,7 +580,18 @@ static int virtio_mmio_probe(struct
platform_device *pdev)
>>
>>       platform_set_drvdata(pdev, vm_dev);
>>
>> -     return register_virtio_device(&vm_dev->vdev);
>> +     rc = register_virtio_device(&vm_dev->vdev);
>> +     if (rc)
>> +             goto unmap;
>> +     return 0;
>> +unmap:
>> +     iounmap(vm_dev->base);
>> +free_mem:
>> +     devm_release_mem_region(&pdev->dev, mem->start,
>> +                     resource_size(mem));
>> +free_vmdev:
>> +     devm_kfree(&pdev->dev, vm_dev);
>
> I think this is problematic as vm_dev embeds a struct device (via
> embedding a struct virtio_device). I think the right way to do this is
> - call this only if register_virtio_device() has not been called
> - put the devm_kfree() into the ->release callback for the
>   virtio_device (IOW, replace virtio_mmio_release_dev_empty() with a
>   function that calls this)
> - do a put_device() if register_virtio_device() failed
>
> I might be missing some interaction between the usual driver model
> handling and devm resources, though.
>
if fail in virtio_mmio_probe, we need free @mem of @pdev, vdev->base,
so I prefer clean all this resource in virtio_mmio_probe itself, keep
vdev.dev.release do nothing.
also we need release these resources at virtio_mmio_remove.
I'll send V2.

--
thanks a ton