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

From: Christoph Hellwig <hch@infradead.org>
To: Uwe Kleine-K??nig <u.kleine-koenig@pengutronix.de>
Cc: Christoph Hellwig <hch@infradead.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	linux-pci@vger.kernel.org,
	Alexander Duyck <alexanderduyck@fb.com>,
	oss-drivers@corigine.com, Paul Mackerras <paulus@samba.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Rafa?? Mi??ecki <zajec5@gmail.com>,
	Jesse Brandeburg <jesse.brandeburg@intel.com>,
	Bjorn Helgaas <helgaas@kernel.org>,
	Ido Schimmel <idosch@nvidia.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Yisen Zhuang <yisen.zhuang@huawei.com>,
	Vadym Kochan <vkochan@marvell.com>, Michael Buesch <m@bues.ch>,
	Jiri Pirko <jiri@nvidia.com>,
	Salil Mehta <salil.mehta@huawei.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
	Taras Chornyi <tchornyi@marvell.com>,
	Zhou Wang <wangzhou1@hisilicon.com>,
	linux-crypto@vger.kernel.org, kernel@pengutronix.de,
	netdev@vger.kernel.org, Simon Horman <simon.horman@corigine.com>,
	Oliver O'Halloran <oohall@gmail.com>,
	linuxppc-dev@lists.ozlabs.org,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH v3 4/8] PCI: replace pci_dev::driver usage that gets the driver name
Date: Sat, 14 Aug 2021 09:38:34 +0100	[thread overview]
Message-ID: <YReBCtWxvmDx7Uqg@infradead.org> (raw)
In-Reply-To: <20210812081425.7pjy4a25e2ehkr3x@pengutronix.de>

On Thu, Aug 12, 2021 at 10:14:25AM +0200, Uwe Kleine-K??nig wrote:
> dev_driver_string() might return "" (via dev_bus_name()). If that happens
> *drvstr == '\0' becomes true.
> 
> Would the following be better?:
> 
> 	const char *drvstr;
> 
> 	if (pdev)
> 		return "<null>";
> 
> 	drvstr = dev_driver_string(&pdev->dev);
> 
> 	if (!strcmp(drvstr, ""))
> 		return "<null>";
> 
> 	return drvstr;
> 
> When I thought about this hunk I considered it ugly to have "<null>" in
> it twice.

Well, if you want to avoid that you can do:

	if (pdev) {
		const char *name = dev_driver_string(&pdev->dev);

		if (strcmp(drvstr, ""))
			return name;
	}
	return "<null>";

Which would be a lot more readable.