linux-kernel - Re: [PATCH v4 1/3] driver-core: return EINVAL error instead of BUG

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Message-ID: <800f5947-96e0-085d-e127-894ee2a18e69@geekplace.eu>
Date:   Wed, 16 May 2018 18:07:58 +0200
From:   Florian Schmaus <flo@...kplace.eu>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/3] driver-core: return EINVAL error instead of
 BUG_ON()

On 16.05.2018 17:39, Greg Kroah-Hartman wrote:
> On Wed, May 16, 2018 at 02:05:25PM +0200, Florian Schmaus wrote:
>> I triggerd the BUG_ON() in driver_register() when booting a domU Xen
>> domain. Since there was no contextual information logged, I needed to
>> attach kgdb to determine the culprit (the wmi-bmof driver in my
>> case). The BUG_ON() was added in commit f48f3febb2cb ("driver-core: do
>> not register a driver with bus_type not registered").
>>
>> Instead of running into a BUG_ON() we print an error message
>> identifying the, likely faulty, driver but continue booting.
>>
>> Signed-off-by: Florian Schmaus <flo@...kplace.eu>
>> ---
>>
>> Notes:
>>     - Also print out the bus name
>>     - Use pr_err() instead of printk()
>>
>>  drivers/base/driver.c | 7 ++++++-
>>  1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/driver.c b/drivers/base/driver.c
>> index ba912558a510..203fa731e3ee 100644
>> --- a/drivers/base/driver.c
>> +++ b/drivers/base/driver.c
>> @@ -148,7 +148,12 @@ int driver_register(struct device_driver *drv)
>>  	int ret;
>>  	struct device_driver *other;
>>  
>> -	BUG_ON(!drv->bus->p);
>> +	if (!drv->bus->p) {
>> +		pr_err("Driver '%s' was unable to register with bus_type '%s'"
>> +			   " because it was not initialized.\n",
> 
> Are you using checkpatch.pl?

I do, I thought this was one of the rare occasions where it is sensible
to split the lines, also given that the other strings within the same
function are also split.

> Anyway, long strings should never be split across lines.  This needs to
> be one line.

Fixed in v5.

> Sometimes making small changes is hard :)

True words ;)

- Florian



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