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. Thanks, Amir.
