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tools/memory-model: Add smp_mb__after_srcu_read_unlock()

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This commit adds support for smp_mb__after_srcu_read_unlock(), which,
when combined with a prior srcu_read_unlock(), implies a full memory
barrier.  No ordering is guaranteed to accesses between the two, and
placing accesses between is bad practice in any case.

Tests may be found at https://github.com/paulmckrcu/litmus in files
matching manual/kernel/C-srcu-mb-*.litmus.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2023-01-29 09:41:44 -08:00
parent dd409de256
commit 02bae7a242
3 changed files with 5 additions and 2 deletions
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3
tools/memory-model/linux-kernel.bell
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@ -31,7 +31,8 @@ enum Barriers = 'wmb (*smp_wmb*) ||
'before-atomic (*smp_mb__before_atomic*) ||
'after-atomic (*smp_mb__after_atomic*) ||
'after-spinlock (*smp_mb__after_spinlock*) ||
'after-unlock-lock (*smp_mb__after_unlock_lock*)
'after-unlock-lock (*smp_mb__after_unlock_lock*) ||
'after-srcu-read-unlock (*smp_mb__after_srcu_read_unlock*)
instructions F[Barriers]
(* SRCU *)

3
tools/memory-model/linux-kernel.cat
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@ -49,7 +49,8 @@ let mb = ([M] ; fencerel(Mb) ; [M]) |
* also affected by the fence.
*)
([M] ; po-unlock-lock-po ;
[After-unlock-lock] ; po ; [M])
[After-unlock-lock] ; po ; [M]) |
([M] ; po? ; [Srcu-unlock] ; fencerel(After-srcu-read-unlock) ; [M])
let gp = po ; [Sync-rcu | Sync-srcu] ; po?
let strong-fence = mb | gp

1
tools/memory-model/linux-kernel.def
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@ -24,6 +24,7 @@ smp_mb__before_atomic() { __fence{before-atomic}; }
smp_mb__after_atomic() { __fence{after-atomic}; }
smp_mb__after_spinlock() { __fence{after-spinlock}; }
smp_mb__after_unlock_lock() { __fence{after-unlock-lock}; }
smp_mb__after_srcu_read_unlock() { __fence{after-srcu-read-unlock}; }
barrier() { __fence{barrier}; }
// Exchange