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Date: Thu, 28 May 2015 08:36:46 -0400
From: Sasha Levin <sasha.levin@oracle.com>
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To: Sudip Mukherjee <sudipm.mukherjee@gmail.com>,
        Greg KH <gregkh@linuxfoundation.org>
CC: Alan Stern <stern@rowland.harvard.edu>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Tal Shorer <tal.shorer@gmail.com>,
        USB list <linux-usb@vger.kernel.org>,
        "<linux-kernel@vger.kernel.org>" <linux-kernel@vger.kernel.org>,
        David Cohen <david.a.cohen@linux.intel.com>,
        Felipe Balbi <balbi@ti.com>, Lu Baolu <baolu.lu@linux.intel.com>
Subject: Re: [PATCH] usb: ulpi: don't register drivers if bus doesn't exist
References: <20150527083933.GA13844@kuha.fi.intel.com> <Pine.LNX.4.44L0.1505271109450.1540-100000@iolanthe.rowland.org> <20150527152116.GA1972@kroah.com> <20150528053938.GB2944@sudip-PC>
In-Reply-To: <20150528053938.GB2944@sudip-PC>
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On 05/28/2015 01:39 AM, Sudip Mukherjee wrote:
> diff --git a/drivers/base/driver.c b/drivers/base/driver.c
> index 4eabfe2..1acae5b 100644
> --- a/drivers/base/driver.c
> +++ b/drivers/base/driver.c
> @@ -150,6 +150,11 @@ int driver_register(struct device_driver *drv)
>  	int ret;
>  	struct device_driver *other;
>  
> +	if (!drv->bus->registered) {
> +		pr_err("Driver %s registration failed. bus not yet registered\n",
> +		       drv->name);
> +		return -ENODEV;
> +	}
>  	BUG_ON(!drv->bus->p);

This is a design issue with the code in the layer above, there's no reason
driver_register() should be called with a bus that wasn't registered to
begin with.

This is why there's a BUG_ON there to catch these issues - it's a bug, not
a desired behaviour.


Thanks,
Sasha