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Date:   Mon, 18 Oct 2021 16:15:33 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Denis Kirjanov <dkirjanov@suse.de>
Cc:     Zheyu Ma <zheyuma97@gmail.com>, isdn@linux-pingi.de,
        davem@davemloft.net, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mISDN: Fix return values of the probe function
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In-Reply-To: <02fe8f6c-e332-5286-a759-750f47c3512a@suse.de>
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        <02fe8f6c-e332-5286-a759-750f47c3512a@suse.de>
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On Mon, 18 Oct 2021 20:06:51 +0300 Denis Kirjanov wrote:
> 10/18/21 5:20 PM, Zheyu Ma =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> > During the process of driver probing, the probe function should return =
< 0
> > for failure, otherwise, the kernel will treat value > 0 as success. =20
>=20
> setup_card() checks for the return value.
> Thus it makes sense to submit the patch with net-next tag

setup_card() propagates the value returned by setup_hw() which in turn
gets propagated by hfc_probe() and hits local_pci_probe():

	/*
	 * Probe function should return < 0 for failure, 0 for success
	 * Treat values > 0 as success, but warn.
	 */
	pci_warn(pci_dev, "Driver probe function unexpectedly returned %d\n",
		 rc);
	return 0;

But you're right, this is a minor bug, hfc_remove_pci() checks if
driver data is already NULL so there will be no crash. Just a driver
bound to a device even though probe failed. Still net material tho.