Re: [PATCH] remove BKL from driverfs

[Dave Hansen <haveblue@us.ibm.com>]

CC'ing Al for comments...

Greg KH wrote:
> bleah, a proliferation of a zillion little spinlocks all across the
> kernel is not my idea of fun :(

A zillion locks each with a single purpose is a lot more fun than 1 
lock with a zillion different uses.

> I don't know if a simple spinlock can help us here.  Look at
> driverfs_get_inode() and follow that into the vfs layer.  Make sure all
> of that is race safe (and isn't currently relying on the BKL.)  I'll
> defer to Al Viro's opinion about this, as I don't quite know all of the
> side effects going on at this moment in time.

OK, I agree a simple spinlock is not the way to go because I now see 
the sleepable operations in there.  But, I don't think 
driverfs_get_inode() needs any more locking.  The inode that it 
references is freshly allocated and my only concern would be about 
access from the inode_in_use list.  Maybe down()ing i_sem will provide 
a bit more protection, but unless the access through inode_in_use is 
already a problem, i_sem isn't needed.  Any thoughts, Al?

-- 
Dave Hansen
haveblue@us.ibm.com