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Add GHC 8.10 Make markLiveObject thread-safe (#1076)
1abbd16Hamish Mackenzie
overlays/bootstrap.nix+2
compare with iko/ghcjs-patch-master
unifiedsplit
@@ -155,6 +155,8 @@ in {
155 ++ fromUntil "8.10.1" "8.10.3" ./patches/ghc/ghc-8.10-ubxt.patch
155 ++ fromUntil "8.10.1" "8.10.3" ./patches/ghc/ghc-8.10-ubxt.patch
156 ++ fromUntil "8.10.3" "8.11" ./patches/ghc/ghc-8.10.3-ubxt.patch
156 ++ fromUntil "8.10.3" "8.11" ./patches/ghc/ghc-8.10.3-ubxt.patch
157 ++ final.lib.optional (versionAtLeast "8.6.4") ./patches/ghc/Cabal-3886.patch
157 ++ final.lib.optional (versionAtLeast "8.6.4") ./patches/ghc/Cabal-3886.patch
158+
159+ ++ fromUntil "8.10.3" "8.10.5" ./patches/ghc/ghc-8.10.3-rts-make-markLiveObject-thread-safe.patch
158 ;
160 ;
159 in ({
161 in ({
160 ghc844 = final.callPackage ../compiler/ghc {
162 ghc844 = final.callPackage ../compiler/ghc {
overlays/patches/ghc/ghc-8.10.3-rts-make-markLiveObject-thread-safe.patchnew file+63
@@ -0,0 +1,63 @@
1+From 96f8e2a47c5e53ae5fb86739aecd27c502e7f121 Mon Sep 17 00:00:00 2001
2+From: Ben Gamari <ben@smart-cactus.org>
3+Date: Tue, 23 Feb 2021 18:30:48 +0000
4+Subject: [PATCH] rts: Make markLiveObject thread-safe
5+
6+markLiveObject is called by GC worker threads and therefore must be
7+thread-safe. This was a rather egregious oversight which the testsuite
8+missed.
9+
10+
11+(cherry picked from commit fe28a062e47bd914a6879f2d01ff268983c075ad)
12+---
13+ rts/CheckUnload.c | 10 ++++++++--
14+ rts/LinkerInternals.h | 2 +-
15+ 2 files changed, 9 insertions(+), 3 deletions(-)
16+
17+diff --git a/rts/CheckUnload.c b/rts/CheckUnload.c
18+index 8f834d13fa..345a17cfec 100644
19+--- a/rts/CheckUnload.c
20++++ b/rts/CheckUnload.c
21+@@ -381,11 +381,16 @@ static ObjectCode *findOC(OCSectionIndices *s_indices, const void *addr) {
22+
23+ static bool markObjectLive(void *data STG_UNUSED, StgWord key, const void *value STG_UNUSED) {
24+ ObjectCode *oc = (ObjectCode*)key;
25+- if (oc->mark == object_code_mark_bit) {
26++
27++ // N.B. we may be called by the parallel GC and therefore this must be
28++ // thread-safe. To avoid taking the linker_mutex in the fast path
29++ // (when the object is already marked) we do an atomic exchange here and
30++ // only take the lock in the case that the object is unmarked.
31++ if (xchg(&oc->mark, object_code_mark_bit) == object_code_mark_bit) {
32+ return true; // for hash table iteration
33+ }
34+
35+- oc->mark = object_code_mark_bit;
36++ ACQUIRE_LOCK(&linker_mutex);
37+ // Remove from 'old_objects' list
38+ if (oc->prev != NULL) {
39+ // TODO(osa): Maybe 'prev' should be a pointer to the referencing
40+@@ -405,6 +410,7 @@ static bool markObjectLive(void *data STG_UNUSED, StgWord key, const void *value
41+ objects->prev = oc;
42+ }
43+ objects = oc;
44++ RELEASE_LOCK(&linker_mutex);
45+
46+ // Mark its dependencies
47+ iterHashTable(oc->dependencies, NULL, markObjectLive);
48+diff --git a/rts/LinkerInternals.h b/rts/LinkerInternals.h
49+index 44fe337802..444849fbac 100644
50+--- a/rts/LinkerInternals.h
51++++ b/rts/LinkerInternals.h
52+@@ -262,7 +262,7 @@ struct _ObjectCode {
53+ struct _ObjectCode *next_loaded_object;
54+
55+ // Mark bit
56+- uint8_t mark;
57++ StgWord mark;
58+
59+ // Set of dependencies (ObjectCode*) of the object file. Traverse
60+ // dependencies using `iterHashTable`.
61+--
62+GitLab
63+