From: Simon Marlow <simonmar@microsoft.com>
Date: Fri, 10 Feb 2006 11:21:11 +0000 (+0000)
Subject: STM fix from Tim Harris
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=a5bd056033e0f81e4d8ca30aa7c26cde3a3a132b;hp=6ff106616c1c98542df0a1763f0f9f655b2c8dd5;p=ghc-hetmet.git

STM fix from Tim Harris

Fixes assertion failures with STM and -debug.  Tim says:
Sorry, it's a problem in how nested transactions are handled in
non-SMP builds.  It'll bite when trying to commit a nested transaction
which has read from a TVar but not updated it.

The call to validate_and_acquire_ownership in
stmCommitNestedTransaction should be the same as that in
stmCommitNestedTransaction, i.e.:

  result = validate_and_acquire_ownership(trec, (!use_read_phase), TRUE);
---

diff --git a/ghc/rts/STM.c b/ghc/rts/STM.c
index f94cf15..d3283a9 100644
--- a/ghc/rts/STM.c
+++ b/ghc/rts/STM.c
@@ -999,7 +999,7 @@ StgBool stmCommitNestedTransaction(Capability *cap, StgTRecHeader *trec) {
   lock_stm(trec);
 
   et = trec -> enclosing_trec;
-  result = validate_and_acquire_ownership(trec, FALSE, TRUE);
+  result = validate_and_acquire_ownership(trec, (!use_read_phase), TRUE);
   if (result) {
     // We now know that all the updated locations hold their expected values.