On Fri, Feb 09, 2018 at 01:41:12PM +0100, Andrea Parri wrote: > On Fri, Feb 09, 2018 at 03:29:37AM -0800, Paul E. McKenney wrote: > > On Fri, Feb 09, 2018 at 10:11:10AM +0100, Andrea Parri wrote: > > > On Thu, Feb 08, 2018 at 09:02:19PM +0100, Peter Zijlstra wrote: > > > > On Thu, Feb 08, 2018 at 06:41:06PM +0000, Patrick Bellasi wrote: > > > > > Hi Paul, > > > > > thanks to you and all the involved guys for this useful tool. > > > > > > > > > > I give it a try today and found that by installing herd7 by just > > > > > following the instruction in herdtools7/INSTALL.md, and precisely > > > > > installing it via: > > > > > > > > > > opam install herdtools7 > > > > > > > > > > it seems to give you a tool which fails to run the basic example in > > > > > your README with this error: > > > > > > > > > > File "./linux-kernel.def", line 44, characters 29-30: unexpected '-' (in macros) > > > > > > > > > > As suggested by Will, by building instead herd7 HEAD (commit 44d69c2) > > > > > everything works fine. > > > > > > > > > > Maybe it's a know issue, in case just ignore me. :) > > > > > > > > > > Otherwise, maybe it can be worth to add to the README a note on which > > > > > minimum version of the herd7 tool is required. > > > > > > > > > > opma version (not working) : 7.47, Rev: exported > > > > > master version (working for me) : 7.47+7(dev), Rev: 44d69c2b1b5ca0f97bd138899d31532ee5e4e084 > > > > > > > > Urgh. So that's why it wouldn't work. > > > > > > > > I remember Paul saying you needed the latest version, which is why I > > > > rebuild from opam, but building top of git is a bit much. > > > > > > +1 > > > > > > _Sadly_ enough, co-developers and I were aware of this issue, > > > but it was only mildly reported here (c.f., > > > > > > https://marc.info/?l=linux-kernel&m=151638196427685&w=2 ). > > > > > > This bisects to that (crazy): > > > > > > 2d5fba7782d669c6a1cc577dbc3bf507780273bb > > > ("linux-kernel*: Make RCU identifiers match ASPLOS paper") > > > > > > From repo.: https://github.com/aparri/memory-model > > > > > > which not only did break 7.47, but also made the bell uglier > > > by mixing dashes and underscores in a very same block. > > > > > > As a solution to this issue, I can envisage a partial revert > > > of that commit (just replace those dashes); Paul, Jade, Luc: > > > any better solution? > > > > > > (Sorry for being late on IRC, glad this came out here,) > > > > Or maybe a 7.48 release? > > This would work, _prior upgrade. (This's not my call of course). > > I do however want to iterate, looking again at the above commit: > > 'rb_dep (*smp_read_barrier_depends*) || > - 'rcu_read_lock (*rcu_read_lock*) || > - 'rcu_read_unlock (*rcu_read_unlock*) || > - 'sync (*synchronize_rcu*) || > + 'rcu-lock (*rcu_read_lock*) || > + 'rcu-unlock (*rcu_read_unlock*) || > + 'sync-rcu (*synchronize_rcu*) || > 'before_atomic (*smp_mb__before_atomic*) || > 'after_atomic (*smp_mb__after_atomic*) || > 'after_spinlock (*smp_mb__after_spinlock*) > > The question arises: dash or underscore? This needs to be fixed. The underscore in rb_dep is determined by herd, so the best shot there is to update the model based on the de-Alpha-ication of the kernel, thus (I believe) allowing rb_dep to be removed entirely, along with its underscore. As far as I know, there is nothing preventing removing underscores from before_atomic, after_atomic, and after_spinlock, and the diff below seems to work OK. And I did have to make a litmus test for smp_mb__before_atomic() and smp_mb__after_atomic(). ;-) Thoughts? Thanx, Paul ------------------------------------------------------------------------ diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell index b984bbda01a5..18885ad15de9 100644 --- a/tools/memory-model/linux-kernel.bell +++ b/tools/memory-model/linux-kernel.bell @@ -28,9 +28,9 @@ enum Barriers = 'wmb (*smp_wmb*) || 'rcu-lock (*rcu_read_lock*) || 'rcu-unlock (*rcu_read_unlock*) || 'sync-rcu (*synchronize_rcu*) || - 'before_atomic (*smp_mb__before_atomic*) || - 'after_atomic (*smp_mb__after_atomic*) || - 'after_spinlock (*smp_mb__after_spinlock*) + 'before-atomic (*smp_mb__before_atomic*) || + 'after-atomic (*smp_mb__after_atomic*) || + 'after-spinlock (*smp_mb__after_spinlock*) instructions F[Barriers] (* Compute matching pairs of nested Rcu-lock and Rcu-unlock *) diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat index babe2b3b0bb3..f0d27f813ec2 100644 --- a/tools/memory-model/linux-kernel.cat +++ b/tools/memory-model/linux-kernel.cat @@ -29,9 +29,9 @@ let rb-dep = [R] ; fencerel(Rb_dep) ; [R] let rmb = [R \ Noreturn] ; fencerel(Rmb) ; [R \ Noreturn] let wmb = [W] ; fencerel(Wmb) ; [W] let mb = ([M] ; fencerel(Mb) ; [M]) | - ([M] ; fencerel(Before_atomic) ; [RMW] ; po? ; [M]) | - ([M] ; po? ; [RMW] ; fencerel(After_atomic) ; [M]) | - ([M] ; po? ; [LKW] ; fencerel(After_spinlock) ; [M]) + ([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) | + ([M] ; po? ; [RMW] ; fencerel(After-atomic) ; [M]) | + ([M] ; po? ; [LKW] ; fencerel(After-spinlock) ; [M]) let gp = po ; [Sync-rcu] ; po? let strong-fence = mb | gp diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def index a397387f77cc..f5a1eb04cb64 100644 --- a/tools/memory-model/linux-kernel.def +++ b/tools/memory-model/linux-kernel.def @@ -21,9 +21,9 @@ smp_mb() { __fence{mb} ; } smp_rmb() { __fence{rmb} ; } smp_wmb() { __fence{wmb} ; } smp_read_barrier_depends() { __fence{rb_dep}; } -smp_mb__before_atomic() { __fence{before_atomic} ; } -smp_mb__after_atomic() { __fence{after_atomic} ; } -smp_mb__after_spinlock() { __fence{after_spinlock} ; } +smp_mb__before_atomic() { __fence{before-atomic} ; } +smp_mb__after_atomic() { __fence{after-atomic} ; } +smp_mb__after_spinlock() { __fence{after-spinlock} ; } // Exchange xchg(X,V) __xchg{mb}(X,V)
