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Subject[tip:locking/core] tools/memory-model: Remove duplicated code from lock.cat
Commit-ID:  8559183ccaec97454b2515ac426f113967256cf9
Gitweb: https://git.kernel.org/tip/8559183ccaec97454b2515ac426f113967256cf9
Author: Alan Stern <stern@rowland.harvard.edu>
AuthorDate: Mon, 14 May 2018 16:33:50 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 15 May 2018 08:11:17 +0200

tools/memory-model: Remove duplicated code from lock.cat

This patch simplifies the implementation of spin_is_locked in the
LKMM. It capitalizes on the fact that a failed spin_trylock() and a
spin_is_locked() which returns True have exactly the same semantics
(those of READ_ONCE) and ordering properties (none). Therefore the
two kinds of events can be combined and handled by the same code,
instead of treated separately as they are currently.

Tested-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Akira Yokosawa <akiyks@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Maranget <luc.maranget@inria.fr>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: parri.andrea@gmail.com
Link: http://lkml.kernel.org/r/1526340837-12222-12-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
tools/memory-model/lock.cat | 28 ++++++----------------------
1 file changed, 6 insertions(+), 22 deletions(-)

diff --git a/tools/memory-model/lock.cat b/tools/memory-model/lock.cat
index 3b1439edc818..1f6d67e79065 100644
--- a/tools/memory-model/lock.cat
+++ b/tools/memory-model/lock.cat
@@ -41,11 +41,15 @@ flag ~empty [FW] ; loc ; [ALL-LOCKS] as lock-final
*)
let RL = try RL with emptyset (* defined herd7 >= 7.49 *)
let RU = try RU with emptyset (* defined herd7 >= 7.49 *)
+
+(* Treat RL as a kind of LF: a read with no ordering properties *)
+let LF = LF | RL
+
(*
* Put lock operations in their appropriate classes, but leave UL out of W
* until after the co relation has been generated.
*)
-let R = R | LKR | LF | RL | RU
+let R = R | LKR | LF | RU
let W = W | LKW

let Release = Release | UL
@@ -80,28 +84,8 @@ let all-possible-rfe-lf =

(* Generate all rf relations for LF events *)
with rfe-lf from cross(all-possible-rfe-lf)
-
let rf-lf = rfe-lf | rfi-lf

-(* rf for RL events, ie islocked returning true, similar to LF above *)
-
-(* islocked returning true inside a critical section
- * must read from the opening lock
- *)
-let rfi-rl = ([LKW] ; po-loc ; [RL]) \ ([LKW] ; po-loc ; [UL] ; po-loc)
-
-(* islocked returning true outside critical sections can match any
- * external lock.
- *)
-let all-possible-rfe-rl =
- let possible-rfe-lf r =
- let pair-to-relation p = p ++ 0
- in map pair-to-relation ((LKW * {r}) & loc & ext)
- in map possible-rfe-lf (RL \ range(rfi-rl))
-
-with rfe-rl from cross(all-possible-rfe-rl)
-let rf-rl = rfe-rl | rfi-rl
-
(* Read from unlock, ie islocked returning false, slightly different *)

(* islocked returning false can read from the last po-previous unlock *)
@@ -118,7 +102,7 @@ with rfe-ru from cross(all-possible-rfe-ru)
let rf-ru = rfe-ru | rfi-ru

(* Final rf relation *)
-let rf = rf | rf-lf | rf-rl | rf-ru
+let rf = rf | rf-lf | rf-ru

(* Generate all co relations, including LKW events but not UL *)
let co0 = co0 | ([IW] ; loc ; [LKW]) |
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