Re: [PATCH] mtd: nand: atmel: fix of_irq_get() error check

[Boris Brezillon <boris.brezillon@free-electrons.com>]

Le Sun, 06 Aug 2017 00:14:28 +0300,
Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> a écrit :

> of_irq_get() may return 0 as well as negative error number on failure,
> while the driver only checks for the negative values.  The driver would
> then call devm_request_irq() for IRQ0  in its probe method and never get
> a valid interrupt.
> 
> Check for 'nc->irq <= 0' instead and return -ENXIO from the driver's probe
> iff of_irq_get() returned 0.
> 
> Fixes: f88fc122cc34 ("mtd: nand: Cleanup/rework the atmel_nand driver")
> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
> 
> ---
> The patch is against the 'master' branch of the 'linux-mtd.git' repo --
> the 'nand/fixes'  branch seems too old...
> 
>  drivers/mtd/nand/atmel/nand-controller.c |   12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> Index: linux-mtd/drivers/mtd/nand/atmel/nand-controller.c
> ===================================================================
> --- linux-mtd.orig/drivers/mtd/nand/atmel/nand-controller.c
> +++ linux-mtd/drivers/mtd/nand/atmel/nand-controller.c
> @@ -2078,11 +2078,11 @@ atmel_hsmc_nand_controller_legacy_init(s
>  	}
>  
>  	nc->irq = of_irq_get(nand_np, 0);
> -	if (nc->irq < 0) {
> -		ret = nc->irq;
> -		if (ret != -EPROBE_DEFER)
> +	if (nc->irq <= 0) {
> +		if (nc->irq != -EPROBE_DEFER)
>  			dev_err(dev, "Failed to get IRQ number (err = %d)\n",
> -				ret);
> +				nc->irq);

nc->irq can be 0 here which doesn't make any sense for an error return
code, so I'd suggest to still use ret and move the 'ret = nc->irq ?:
-ENXIO' line before doing the != -EPROBE_DEFER test.

> +		ret = nc->irq ?: -ENXIO;

Why ENXIO and not EINVAL?

>  		goto out;
>  	}
>  
> @@ -2168,11 +2168,11 @@ atmel_hsmc_nand_controller_init(struct a
>  
>  	nc->irq = of_irq_get(np, 0);
>  	of_node_put(np);
> -	if (nc->irq < 0) {
> +	if (nc->irq <= 0) {
>  		if (nc->irq != -EPROBE_DEFER)
>  			dev_err(dev, "Failed to get IRQ number (err = %d)\n",
>  				nc->irq);
> -		return nc->irq;
> +		return nc->irq ?: -ENXIO;
>  	}
>  
>  	np = of_parse_phandle(dev->of_node, "atmel,nfc-io", 0);
>