`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. Iwas 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 therecursive-read is not a good option for that purpose.`