Re: [PATCH 4/5] EDAC/versalnet: Fix device_register() error handling in init_one_mc()

[Borislav Petkov]

On Sun, Mar 22, 2026 at 06:11:45AM -0700, Prasanna Kumar T S M wrote:
> When device_register() fails, it must be followed by put_device()
> rather than kfree(), because device_register() calls
> device_initialize() which sets up the device refcount. The matching
> release function versal_edac_release() handles the actual kfree().
> 
> Also reorder the dev allocation to after edac_mc_alloc() so the error
> path no longer needs a separate err_dev_free label.

Nope.

edac_mc_alloc() is a lot more heavy-weight than a simple k*alloc(). Pls keep
the ordering as it is.

> Fixes: d5fe2fec6c40d ("EDAC: Add a driver for the AMD Versal NET DDR controller")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Prasanna Kumar T S M <ptsm@xxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/edac/versalnet_edac.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/edac/versalnet_edac.c b/drivers/edac/versalnet_edac.c
> index acd51b492772..6463e88ed3d3 100644
> --- a/drivers/edac/versalnet_edac.c
> +++ b/drivers/edac/versalnet_edac.c
> @@ -817,24 +817,26 @@ static int init_one_mc(struct mc_priv *priv, struct platform_device *pdev, int i
>  	if (!name)
>  		return rc;
>  
> -	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> -	if (!dev)
> -		goto err_name_free;
> -
>  	mci = edac_mc_alloc(i, ARRAY_SIZE(layers), layers, sizeof(struct mc_priv));
>  	if (!mci) {
>  		edac_printk(KERN_ERR, EDAC_MC, "Failed memory allocation for MC%d\n", i);
> -		goto err_dev_free;
> +		goto err_name_free;
>  	}
>  
> +	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> +	if (!dev)
> +		goto err_mc_free;
> +
>  	sprintf(name, "versal-net-ddrmc5-edac-%d", i);
>  
>  	dev->init_name = name;
>  	dev->release = versal_edac_release;
>  
>  	rc = device_register(dev);
> -	if (rc)
> +	if (rc) {
> +		put_device(dev);

Why here and not at the error label below?

>  		goto err_mc_free;
> +	}
>  
>  	mci->pdev = dev;
>  	mc_init(mci, dev);
> @@ -856,8 +858,6 @@ static int init_one_mc(struct mc_priv *priv, struct platform_device *pdev, int i
>  	device_unregister(mci->pdev);
>  err_mc_free:
>  	edac_mc_free(mci);
> -err_dev_free:
> -	kfree(dev);
>  err_name_free:
>  	kfree(name);
>  
> -- 
> 2.49.0
> 

-- 
Regards/Gruss,
    Boris.

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