Re: [PATCH v3 3/4] drivers: mci: Add mci_get_device_by_name function

[Sascha Hauer <s.hauer@pengutronix.de>]

On Wed, Sep 02, 2015 at 08:28:52AM +0200, Daniel Schultz wrote:
> Get a 'struct mci' by search after the device name.
> 
> Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
> ---
> 
> Changes:
> 	v3:
> 	New with patch v3
> 
>  drivers/mci/mci-core.c | 16 ++++++++++++++++
>  include/mci.h          |  8 ++++++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
> index c22f932..d6865d1 100644
> --- a/drivers/mci/mci-core.c
> +++ b/drivers/mci/mci-core.c
> @@ -53,6 +53,8 @@
>  		__res & __mask;						\
>  	})
>  
> +LIST_HEAD(mci_list);
> +
>  /**
>   * @file
>   * @brief Memory Card framework
> @@ -1753,6 +1755,8 @@ int mci_register(struct mci_host *host)
>  		mci->dev.id = DEVICE_ID_DYNAMIC;
>  	}
>  
> +	list_add_tail(&mci->list, &mci_list);
> +

mci_register() may fail later in which case you end up with an undefined
entry in the mci_list. This should be done near the end of
mci_register() when it can't fail anymore.

>  	mci->dev.platform_data = host;
>  	mci->dev.parent = host->hw_dev;
>  	mci->host = host;
> @@ -1844,3 +1848,15 @@ void mci_of_parse(struct mci_host *host)
>  
>  	host->non_removable = of_property_read_bool(np, "non-removable");
>  }
> +
> +struct mci *mci_get_device_by_name(const char *name)
> +{
> +	struct mci *dev;
> +
> +	for_each_mci_device(dev) {
> +		if (!strcmp(dev->cdevname, name))
> +			return dev;
> +	}

dev->cdevname is initialized only in mci_card_probe() and only when
actually a card is detected. This causes a NULL pointer exception for
example when a there's no card in a slot. This has to be checked here.

It's a bit confusing when a variable named 'dev' not of type struct
device_d. Please rather use more specific names, like 'mci' in this
case.

I applied a fixed version to the -next branch.

Sascha

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