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authorAlan Stern <stern@rowland.harvard.edu>2019-06-20 11:55:46 -0400
committerPaul E. McKenney <paulmck@linux.ibm.com>2019-06-21 16:20:49 -0700
commit15aa25cbf0ccc4bd63ed6f2a8065decb7f5e6f89 (patch)
treee3a2ee56ed0089cb5795217eddf0dc3d503eb76a /tools
parentf9de417121001879d92a86960647adb06b5b81bf (diff)
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tools/memory-model: Change definition of rcu-fence
The rcu-fence relation in the Linux Kernel Memory Model is not well named. It doesn't act like any other fence relation, in that it does not relate events before a fence to events after that fence. All it does is relate certain RCU events to one another (those that are ordered by the RCU Guarantee); this induces an actual strong-fence-like relation linking events preceding the first RCU event to those following the second. This patch renames rcu-fence, now called rcu-order. It adds a new definition of rcu-fence, something which should have been present all along because it is used in the rb relation. And it modifies the fence and strong-fence relations by making them incorporate the new rcu-fence. As a result of this change, there is no longer any need to define full-fence in the section for detecting data races. It can simply be replaced by the updated strong-fence relation. This change should have no effect on the operation of the memory model. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Andrea Parri <andrea.parri@amarulasolutions.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/memory-model/linux-kernel.cat23
1 files changed, 13 insertions, 10 deletions
diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat
index 8b61218c99fd..ca2f4297b4e6 100644
--- a/tools/memory-model/linux-kernel.cat
+++ b/tools/memory-model/linux-kernel.cat
@@ -122,24 +122,28 @@ let rcu-link = po? ; hb* ; pb* ; prop ; po
(*
* Any sequence containing at least as many grace periods as RCU read-side
- * critical sections (joined by rcu-link) acts as a generalized strong fence.
+ * critical sections (joined by rcu-link) induces order like a generalized
+ * inter-CPU strong fence.
* Likewise for SRCU grace periods and read-side critical sections, provided
* the synchronize_srcu() and srcu_read_[un]lock() calls refer to the same
* struct srcu_struct location.
*)
-let rec rcu-fence = rcu-gp | srcu-gp |
+let rec rcu-order = rcu-gp | srcu-gp |
(rcu-gp ; rcu-link ; rcu-rscsi) |
((srcu-gp ; rcu-link ; srcu-rscsi) & loc) |
(rcu-rscsi ; rcu-link ; rcu-gp) |
((srcu-rscsi ; rcu-link ; srcu-gp) & loc) |
- (rcu-gp ; rcu-link ; rcu-fence ; rcu-link ; rcu-rscsi) |
- ((srcu-gp ; rcu-link ; rcu-fence ; rcu-link ; srcu-rscsi) & loc) |
- (rcu-rscsi ; rcu-link ; rcu-fence ; rcu-link ; rcu-gp) |
- ((srcu-rscsi ; rcu-link ; rcu-fence ; rcu-link ; srcu-gp) & loc) |
- (rcu-fence ; rcu-link ; rcu-fence)
+ (rcu-gp ; rcu-link ; rcu-order ; rcu-link ; rcu-rscsi) |
+ ((srcu-gp ; rcu-link ; rcu-order ; rcu-link ; srcu-rscsi) & loc) |
+ (rcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; rcu-gp) |
+ ((srcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; srcu-gp) & loc) |
+ (rcu-order ; rcu-link ; rcu-order)
+let rcu-fence = po ; rcu-order ; po?
+let fence = fence | rcu-fence
+let strong-fence = strong-fence | rcu-fence
(* rb orders instructions just as pb does *)
-let rb = prop ; po ; rcu-fence ; po? ; hb* ; pb* ; [Marked]
+let rb = prop ; rcu-fence ; hb* ; pb* ; [Marked]
irreflexive rb as rcu
@@ -163,9 +167,8 @@ flag ~empty mixed-accesses as mixed-accesses
(* Executes-before and visibility *)
let xbstar = (hb | pb | rb)*
-let full-fence = strong-fence | (po ; rcu-fence ; po?)
let vis = cumul-fence* ; rfe? ; [Marked] ;
- ((full-fence ; [Marked] ; xbstar) | (xbstar & int))
+ ((strong-fence ; [Marked] ; xbstar) | (xbstar & int))
(* Boundaries for lifetimes of plain accesses *)
let w-pre-bounded = [Marked] ; (addr | fence)?