netdev - Re: [PATCH] net: ibm: emac: Fix some error handling path in 'emac

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Date:   Sat, 19 Aug 2017 15:22:56 +0200
From:   Christian Lamparter <chunkeey@...glemail.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     davem@...emloft.net, jarod@...hat.com, ivan@...ibm.com,
        ebiggers@...gle.com, tklauser@...tanz.ch, tremyfr@...il.com,
        robh@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] net: ibm: emac: Fix some error handling path in 'emac_probe()'

On Saturday, August 19, 2017 1:07:57 AM CEST Christophe JAILLET wrote:
> If 'irq_of_parse_and_map()' or 'of_address_to_resource()' fail, 'err' is
> known to be 0 at this point.
> So return -ENODEV instead in the first case and propagate the error
> returned by 'of_address_to_resource()' in the 2nd case.
> 
> While at it, turn a 'err != 0' test into an equivalent 'err' to be more
> consistent.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
>  drivers/net/ethernet/ibm/emac/core.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ibm/emac/core.c b/drivers/net/ethernet/ibm/emac/core.c
> index 95135d20458f..1af56a97fb47 100644
> --- a/drivers/net/ethernet/ibm/emac/core.c
> +++ b/drivers/net/ethernet/ibm/emac/core.c
> [...]
>  	/* Map EMAC regs */
> -	if (of_address_to_resource(np, 0, &dev->rsrc_regs)) {
> +	err = of_address_to_resource(np, 0, &dev->rsrc_regs);
> +	if (err) {
>  		printk(KERN_ERR "%pOF: Can't get registers address\n", np);
>  		goto err_irq_unmap;
>  	}
>  // TODO : request_mem_region
>  dev->emacp = ioremap(dev->rsrc_regs.start,
>                       resource_size(&dev->rsrc_regs));
>  ...

If you want to go for 101%: you could get rid of this block
altogether by doing: 
	dev->emacp = of_iomap(np, 0);

Note1:
This will also make the rsrc_regs variable in the emac_instance
struct redundant. So simply remove it from the core.h.

Note2: if you want to go for 110%, you could replace this with
platform_get_resource() and devm_ioremap_resource() (if you
are interested, take a look at devm_ioremap_resource's kdoc
it has an example).

Thanks,
Christian