On 05/15/2018 02:05 PM, Peter Zijlstra wrote: > On Tue, May 15, 2018 at 02:02:00PM -0400, Waiman Long wrote: >> On 05/15/2018 01:58 PM, Peter Zijlstra wrote: >>> On Tue, May 15, 2018 at 01:38:04PM -0400, Waiman Long wrote: >>>> +/* >>>> + * Owner value to indicate the rwsem's owner is not currently known. >>>> + */ >>>> +#define RWSEM_OWNER_UNKNOWN ((struct task_struct *)-1) >>> It might be nice to comment that this works and relies on having that >>> ANON_OWNER bit set. >> I am just trying not to expose internal working of rwsem, but I can >> document that one of the bits is the real deal without specifying which one. > Thing is, you don't want someone changing this without knowing about > that one magic bit. It doesn't hurt to be explicit here. > > Also, do we want -1L instead of a -1 literal? > Yes, I should -1L instead. Cheers, Longman
