Re: [PATCH][-mm] reclassify sg_sysfs_class for lockdep

["Dave Young" <hidave.darkstar@gmail.com>]

On Wed, May 28, 2008 at 10:40 PM, James Bottomley
<James.Bottomley@hansenpartnership.com> wrote:
> On Tue, 2008-05-27 at 18:10 +0800, Dave Young wrote:
>> As register sg_interface, the sg_add will be called, which then will
>> add device to sg_sysfs_class. This will cause lockdep warning,
>> please see following email
>>
>> In this case the locks are from diffrent classi, one is sdev_class,
>> another is sg_sysfs_class
>>
>> Here reclassify the sg_sysfs_class for lockdep
>
> This isn't really a generic solution, is it?  It only works because we
> currently only have two users of the interface functions, so if we
> reclassify one they look separate to lockdep.  It will fall over again
> if we ever get another one.
>
> Surely the correct fix is to initialise lockdep for the mutex the same
> way we did for the semaphore in class_register() (which does exactly the
> same locking without triggering lockdep)?  That way we'll also fix the
> problem for other conversions of semaphore->mutex.

Matthew & greg did the work already.

>From my original idea I don't want to do this for all classes, and I
would think it as a rare case.

Regards
dave