On 05/15/2018 02:05 PM, Amir Goldstein wrote: > On Tue, May 15, 2018 at 9:02 PM, Waiman Long <longman@xxxxxxxxxx> 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. >> > BUILD_BUG_ON(!rwsem_has_anonymous_owner(RWSEM_OWNER_UNKNOWN)) > inside rwsem.c and comment above to explain it. Yes, it is a good idea. I will do that. -Longman
