On Tue, Sep 05, 2017 at 03:46:43PM +0200, Peter Zijlstra wrote: > On Tue, Sep 05, 2017 at 07:58:38PM +0900, Byungchul Park wrote: > > On Tue, Sep 05, 2017 at 07:31:44PM +0900, Byungchul Park wrote: > > > Recursive-read and the hint I proposed(a.k.a. might) should be used for > > > their different specific applications. Both meaning and constraints of > > > them are totally different. > > > > > > Using a right function semantically is more important than making it > > > just work, as you know. Wrong? > > > Of course, in the following cases, the results are same: > > > > recursive-read(A) -> recursive-read(A), is like nothing, and also > > might(A) -> might(A) , is like nothing. > > > > recursive-read(A) -> lock(A), end in a deadlock, and also > > might(A) -> lock(A), end in a deadlock. > > And these are exactly the cases we need. > > > Futhermore, recursive-read-might() can be used if needed, since their > > semantics are orthogonal so they can be used in mixed forms. > > > > I really hope you accept the new semantics... I think current workqueue > > code exactly needs the semantics. > > I really don't want to introduce this extra state if we don't have to. > And as you already noted, this 'might' thing of yours doesn't belong in > the .read argument, since as you say its orthogonal.
Right. Of course, it can be changed to be a proper form if allowed. I was afraid to introduce another new function instead of using an arg. > recursive-read > wait_for_completion() > recursive-read > complete() > > is fundamentally not a deadlock, we don't need anything extra. It might be ok wrt the workqueue. But, I think generally the recursive-read is not a good option for that purpose.
