On Fri, 2016-07-22 at 12:26 -0700, Davidlohr Bueso wrote: > On Fri, 22 Jul 2016, Imre Deak wrote: > > > On Fri, 2016-07-22 at 11:03 -0700, Davidlohr Bueso wrote: > > > On Fri, 22 Jul 2016, Waiman Long wrote: > > > > > > > I think making mutex_trylock() fail maybe a bit too far. Do we > > > > really > > > > have any real workload that cause starvation problem because > > > > of > > > > that. > > > > Code that does mutex_trylock() in a loop can certainly cause > > > > lock > > > > starvation, but it is not how mutex_trylock() is supposed to be > > > > used. > > > > We can't build in safeguard for all the possible abuses of the > > > > mutex > > > > APIs. > > > > > > True, and that's actually why I think that 'fixing' the > > > !SPIN_ON_OWNER case > > > is a bit too far in the first place: most of the archs that will > > > care > > > about > > > this already have ARCH_SUPPORTS_ATOMIC_RMW. The extra code for > > > dealing with > > > this is not worth it imo. > > > > SPIN_ON_OWNER is also disabled in case of DEBUG_MUTEXES, which is > > the > > config where I wanted to avoid starvation in the first place. > > Well yes, but know of course that that option is even less common > than > archs with non atomic Rmw.
The point is that it's broken atm. --Imre