Messages in this thread | | | Date | Wed, 20 Nov 2013 01:30:39 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH] sysfs: use a separate locking class for open files depending on mmap |
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On Sun, Nov 17, 2013 at 08:45:23PM -0800, Greg Kroah-Hartman wrote: > On Sun, Nov 17, 2013 at 12:29:37PM +0900, Tejun Heo wrote: > > On Sat, Nov 16, 2013 at 10:21:19PM -0500, Dave Jones wrote: > > > On Sun, Nov 17, 2013 at 11:17:36AM +0900, Tejun Heo wrote: > > > > > > > > > > + if (has_mmap) > > > > + mutex_init(&of->mutex); > > > > + else > > > > + mutex_init(&of->mutex); > > > > > > ummm... > > > > Supposed to look that way. It'll give two separate static lock class > > keys to of->mutex. Yeah, looks weird. Any better ideas? > > Doesn't gcc optimize that away to just one lock class anyway?
Well, it basically becomes
if (has_mmap) { static struct lock_class_key key; __mutex_init(blah, &key); } else { static struct lock_class_key key; __mutex_init(blah, &key); }
So, the compiler isn't allowed to merge the two keys and we actually use constructs like the above from a few places. Yeah, it is weird but does work.
Thanks.
-- tejun
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