linux-kernel - Re: [PATCH v3 4/8] PCI: replace pci_dev::driver usage that gets the driver name

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Message-ID: <YRTIqGm5Dr8du7a7@infradead.org>
Date:   Thu, 12 Aug 2021 08:07:20 +0100
From:   Christoph Hellwig <hch@...radead.org>
To:     Uwe Kleine-K??nig <u.kleine-koenig@...gutronix.de>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-pci@...r.kernel.org, kernel@...gutronix.de,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Rafa?? Mi??ecki <zajec5@...il.com>,
        Zhou Wang <wangzhou1@...ilicon.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Yisen Zhuang <yisen.zhuang@...wei.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Vadym Kochan <vkochan@...vell.com>,
        Taras Chornyi <tchornyi@...vell.com>,
        Jiri Pirko <jiri@...dia.com>, Ido Schimmel <idosch@...dia.com>,
        Simon Horman <simon.horman@...igine.com>,
        Michael Buesch <m@...s.ch>,
        Oliver O'Halloran <oohall@...il.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Alexander Duyck <alexanderduyck@...com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-wireless@...r.kernel.org, linux-crypto@...r.kernel.org,
        netdev@...r.kernel.org, oss-drivers@...igine.com
Subject: Re: [PATCH v3 4/8] PCI: replace pci_dev::driver usage that gets the
 driver name

On Wed, Aug 11, 2021 at 10:06:33AM +0200, Uwe Kleine-K??nig wrote:
>  static inline const char *eeh_driver_name(struct pci_dev *pdev)
>  {
> -	return (pdev && pdev->driver) ? pdev->driver->name : "<null>";
> +	const char *drvstr = pdev ? dev_driver_string(&pdev->dev) : "";
> +
> +	if (*drvstr == '\0')
> +		return "<null>";
> +
> +	return drvstr;

This looks rather obsfucated due to the fact that dev_driver_string
never returns '\0', and due to the strange mix of a tenary operation
and the if on a related condition.


>  }
>  
>  #endif /* CONFIG_EEH */
> diff --git a/drivers/bcma/host_pci.c b/drivers/bcma/host_pci.c
> index 69c10a7b7c61..dc2ffa686964 100644
> --- a/drivers/bcma/host_pci.c
> +++ b/drivers/bcma/host_pci.c
> @@ -175,9 +175,10 @@ static int bcma_host_pci_probe(struct pci_dev *dev,
>  	if (err)
>  		goto err_kfree_bus;
>  
> -	name = dev_name(&dev->dev);
> -	if (dev->driver && dev->driver->name)
> -		name = dev->driver->name;
> +	name = dev_driver_string(&dev->dev);
> +	if (*name == '\0')
> +		name = dev_name(&dev->dev);

Where does this '\0' check come from?

> +
> +	name = dev_driver_string(&dev->dev);
> +	if (*name == '\0')
> +		name = dev_name(&dev->dev);
> +

More of this weirdness.