[PATCH] tpm: Fix initialization of the cdev

[PATCH] tpm: Fix initialization of the cdev

[Jason Gunthorpe]

When a cdev is contained in a dynamic structure the cdev parent kobj
should be set to the kobj that controls the lifetime of the enclosing
structure. In TPM's case this is the embedded struct device.

Also, cdev_init 0's the whole structure, so all sets must be after,
not before. This fixes module ref counting and cdev.

Fixes: 313d21eeab92 ("tpm: device class for tpm")
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
---
 drivers/char/tpm/tpm-chip.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Peter, I've only compile tests this. Thanks

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 283f00a7f036..1082d4bb016a 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -129,8 +129,9 @@ struct tpm_chip *tpmm_chip_alloc(struct device *dev,
 
 	device_initialize(&chip->dev);
 
-	chip->cdev.owner = chip->pdev->driver->owner;
 	cdev_init(&chip->cdev, &tpm_fops);
+	chip->cdev.owner = chip->pdev->driver->owner;
+	chip->cdev.kobj.parent = &chip->dev.kobj;
 
 	return chip;
 }
-- 
2.1.4

Re: [PATCH] tpm: Fix initialization of the cdev

[Dmitry Torokhov]

On Tue, Jun 30, 2015 at 01:15:31PM -0600, Jason Gunthorpe wrote:
> When a cdev is contained in a dynamic structure the cdev parent kobj
> should be set to the kobj that controls the lifetime of the enclosing
> structure. In TPM's case this is the embedded struct device.
> 
> Also, cdev_init 0's the whole structure, so all sets must be after,
> not before. This fixes module ref counting and cdev.
> 
> Fixes: 313d21eeab92 ("tpm: device class for tpm")
> Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>

Right, when embedding cdev its lifetime should be tied to the lifetime
of the enclosing structure.

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

> ---
>  drivers/char/tpm/tpm-chip.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> Peter, I've only compile tests this. Thanks
> 
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 283f00a7f036..1082d4bb016a 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -129,8 +129,9 @@ struct tpm_chip *tpmm_chip_alloc(struct device *dev,
>  
>  	device_initialize(&chip->dev);
>  
> -	chip->cdev.owner = chip->pdev->driver->owner;
>  	cdev_init(&chip->cdev, &tpm_fops);
> +	chip->cdev.owner = chip->pdev->driver->owner;
> +	chip->cdev.kobj.parent = &chip->dev.kobj;
>  
>  	return chip;
>  }
> -- 
> 2.1.4
> --
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-- 
Dmitry