Re: [PATCH RFC tip/lkmm 08/10] EXP Remove understore from smp_mb__before_atomic() workings

From: Andrea Parri
Date: Thu Feb 15 2018 - 17:30:29 EST


On Fri, Feb 09, 2018 at 06:20:29AM -0800, Paul E. McKenney wrote:
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>

nit: s/understore/underscore (a very understandable lapsus, BTW ;-)

According to the cover letter, patches 8-10 of this series are intended
to be squashed together; it could be useful to add a description then:
the motivation for these changes might appear "trivial" today; months/
years from now? mmh, I can't put my finger on it ;-)

IMO, this descrition should also mention why this solution "is the way
to go" (e.g., compare with the solution recently implemented by Akira).

Andrea


> ---
> tools/memory-model/linux-kernel.bell | 2 +-
> tools/memory-model/linux-kernel.cat | 2 +-
> tools/memory-model/linux-kernel.def | 2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell
> index b984bbda01a5..558bbef9e08a 100644
> --- a/tools/memory-model/linux-kernel.bell
> +++ b/tools/memory-model/linux-kernel.bell
> @@ -28,7 +28,7 @@ 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*) ||
> + 'before-atomic (*smp_mb__before_atomic*) ||
> 'after_atomic (*smp_mb__after_atomic*) ||
> 'after_spinlock (*smp_mb__after_spinlock*)
> instructions F[Barriers]
> diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat
> index babe2b3b0bb3..31c08a44c088 100644
> --- a/tools/memory-model/linux-kernel.cat
> +++ b/tools/memory-model/linux-kernel.cat
> @@ -29,7 +29,7 @@ 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] ; 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?
> diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def
> index a397387f77cc..ff4b756f4a44 100644
> --- a/tools/memory-model/linux-kernel.def
> +++ b/tools/memory-model/linux-kernel.def
> @@ -21,7 +21,7 @@ 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__before_atomic() { __fence{before-atomic} ; }
> smp_mb__after_atomic() { __fence{after_atomic} ; }
> smp_mb__after_spinlock() { __fence{after_spinlock} ; }
>
> --
> 2.5.2
>