From: Bjorn Helgaas <bjorn.helgaas@hp.com>
To: Jes Sorensen <jes@sgi.com>
Subject: Re: initcall at ... returned with error code -19 (Was: Re: 2.6.16-rc5-mm2)
Date: Tue, 7 Mar 2006 10:31:32 -0700
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Cc: Paul Jackson <pj@sgi.com>, Andrew Morton <akpm@osdl.org>,
       jesper.juhl@gmail.com, linux-kernel@vger.kernel.org
References: <9a8748490603061359r64655a45i9a26e1f92009c7bf@mail.gmail.com> <20060306170919.0fcd8566.pj@sgi.com> <yq0veuq2yeu.fsf@jaguar.mkp.net>
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On Tuesday 07 March 2006 06:10, Jes Sorensen wrote:
> >>>>> "Paul" == Paul Jackson <pj@sgi.com> writes:
> Paul> Andrew wrote:
> >> That's OK - it's -ENODEV.
> 
> Paul> I can't help but wonder if the particular case of -ENODEV should
> Paul> be kept quiet, as in the following totally untested patch:
> 
> I'd subscribe to that. It seems a bit wrong to return 0 in a
> loadable module if nothing is found, and some of the ones people have
> posted patches for converting can be either modules or static.

Yeah, maybe.  But it feels a little like the question of whether
{pci,pnp,acpi_bus}_register_driver() should return the number of
devices found.  The consensus is that these functions should return
only a negative error, or zero for success, leaving any counting of
devices to the driver's .probe() or .add() method.

I think a loadable driver's init function *should* return success
even if no device is yet present.  Maybe you want to load the driver
before hot-adding the device.

The common idiom of, e.g.,

    static int __init serial8250_pci_init(void)
    {
        return pci_register_driver(&serial_pci_driver);
    }

should remain acceptable, though it returns 0 even if no devices
are found.

Bjorn
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