[Git][ghc/ghc][wip/T23088] 2 commits: rts: Don't rely on EXTERN_INLINE for slop-zeroing logic
Ben Gamari (@bgamari)
gitlab at gitlab.haskell.org
Thu Mar 23 17:53:04 UTC 2023
Ben Gamari pushed to branch wip/T23088 at Glasgow Haskell Compiler / GHC
Commits:
f21cdda2 by Ben Gamari at 2023-03-23T13:52:58-04:00
rts: Don't rely on EXTERN_INLINE for slop-zeroing logic
Previously we relied on calling EXTERN_INLINE functions defined in
ClosureMacros.h from Cmm to zero slop. However, as far as I can tell,
this is no longer safe to do in C99 as EXTERN_INLINE definitions may be emitted
in each compilation unit.
Fix this by explicitly declaring a new set of non-inline functions in
ZeroSlop.c which can be called from Cmm and marking the ClosureMacros.h
definitions as INLINE_HEADER.
In the future we should try to eliminate EXTERN_INLINE.
- - - - -
25422c95 by Ben Gamari at 2023-03-23T13:52:58-04:00
rts: Fix capability-count check in zeroSlop
Previously `zeroSlop` examined `RtsFlags` to determine whether the
program was single-threaded. This is wrong; a program may be started
with `+RTS -N1` yet the process may later increase the capability count
with `setNumCapabilities`. This lead to quite subtle and rare crashes.
Fixes #23088.
- - - - -
4 changed files:
- + rts/ZeroSlop.c
- rts/include/Cmm.h
- rts/include/rts/storage/ClosureMacros.h
- rts/rts.cabal.in
Changes:
=====================================
rts/ZeroSlop.c
=====================================
@@ -0,0 +1,27 @@
+/* ----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team, 1998-2012
+ *
+ * Utilities for zeroing slop callable from Cmm
+ *
+ * N.B. If you are in C you should rather using the inlineable utilities
+ * (e.g. overwritingClosure) defined in ClosureMacros.h.
+ *
+ * -------------------------------------------------------------------------- */
+
+#include "Rts.h"
+
+void stg_overwritingClosure (StgClosure *p)
+{
+ overwritingClosure(p);
+}
+
+void stg_overwritingMutableClosureOfs (StgClosure *p, uint32_t offset)
+{
+ overwritingMutableClosureOfs(p, offset);
+}
+
+void stg_overwritingClosureSize (StgClosure *p, uint32_t size /* in words */)
+{
+ overwritingClosureSize(p, size);
+}
=====================================
rts/include/Cmm.h
=====================================
@@ -647,9 +647,9 @@
#define mutArrPtrsCardWords(n) ROUNDUP_BYTES_TO_WDS(mutArrPtrCardUp(n))
#if defined(PROFILING) || defined(DEBUG)
-#define OVERWRITING_CLOSURE_SIZE(c, size) foreign "C" overwritingClosureSize(c "ptr", size)
-#define OVERWRITING_CLOSURE(c) foreign "C" overwritingClosure(c "ptr")
-#define OVERWRITING_CLOSURE_MUTABLE(c, off) foreign "C" overwritingMutableClosureOfs(c "ptr", off)
+#define OVERWRITING_CLOSURE_SIZE(c, size) foreign "C" stg_overwritingClosureSize(c "ptr", size)
+#define OVERWRITING_CLOSURE(c) foreign "C" stg_overwritingClosure(c "ptr")
+#define OVERWRITING_CLOSURE_MUTABLE(c, off) foreign "C" stg_overwritingMutableClosureOfs(c "ptr", off)
#else
#define OVERWRITING_CLOSURE_SIZE(c, size) /* nothing */
#define OVERWRITING_CLOSURE(c) /* nothing */
@@ -657,7 +657,7 @@
* this whenever profiling is enabled as described in Note [slop on the heap]
* in Storage.c. */
#define OVERWRITING_CLOSURE_MUTABLE(c, off) \
- if (TO_W_(RtsFlags_ProfFlags_doHeapProfile(RtsFlags)) != 0) { foreign "C" overwritingMutableClosureOfs(c "ptr", off); }
+ if (TO_W_(RtsFlags_ProfFlags_doHeapProfile(RtsFlags)) != 0) { foreign "C" stg_overwritingMutableClosureOfs(c "ptr", off); }
#endif
#define IS_STACK_CLEAN(stack) \
=====================================
rts/include/rts/storage/ClosureMacros.h
=====================================
@@ -517,16 +517,12 @@ void LDV_recordDead (const StgClosure *c, uint32_t size);
RTS_PRIVATE bool isInherentlyUsed ( StgHalfWord closure_type );
#endif
-EXTERN_INLINE void
-zeroSlop (
- StgClosure *p,
- uint32_t offset, /*< offset to start zeroing at, in words */
- uint32_t size, /*< total closure size, in words */
- bool known_mutable /*< is this a closure who's slop we can always zero? */
- );
-
-EXTERN_INLINE void
-zeroSlop (StgClosure *p, uint32_t offset, uint32_t size, bool known_mutable)
+INLINE_HEADER void
+zeroSlop (StgClosure *p,
+ uint32_t offset, /*< offset to start zeroing at, in words */
+ uint32_t size, /*< total closure size, in words */
+ bool known_mutable /*< is this a closure who's slop we can always zero? */
+ )
{
// see Note [zeroing slop when overwriting closures], also #8402
@@ -539,9 +535,8 @@ zeroSlop (StgClosure *p, uint32_t offset, uint32_t size, bool known_mutable)
#endif
;
- const bool can_zero_immutable_slop =
- // Only if we're running single threaded.
- RTS_DEREF(RtsFlags).ParFlags.nCapabilities <= 1;
+ // Only if we're running single threaded.
+ const bool can_zero_immutable_slop = getNumCapabilities() == 1;
const bool zero_slop_immutable =
want_to_zero_immutable_slop && can_zero_immutable_slop;
@@ -574,8 +569,10 @@ zeroSlop (StgClosure *p, uint32_t offset, uint32_t size, bool known_mutable)
}
}
-EXTERN_INLINE void overwritingClosure (StgClosure *p);
-EXTERN_INLINE void overwritingClosure (StgClosure *p)
+// N.B. the stg_* variants of the utilities below are only for calling from
+// Cmm. The INLINE_HEADER functions should be used when in C.
+void stg_overwritingClosure (StgClosure *p);
+INLINE_HEADER void overwritingClosure (StgClosure *p)
{
W_ size = closure_sizeW(p);
#if defined(PROFILING)
@@ -585,15 +582,13 @@ EXTERN_INLINE void overwritingClosure (StgClosure *p)
zeroSlop(p, sizeofW(StgThunkHeader), size, /*known_mutable=*/false);
}
+
// Version of 'overwritingClosure' which overwrites only a suffix of a
// closure. The offset is expressed in words relative to 'p' and shall
// be less than or equal to closure_sizeW(p), and usually at least as
// large as the respective thunk header.
-EXTERN_INLINE void
-overwritingMutableClosureOfs (StgClosure *p, uint32_t offset);
-
-EXTERN_INLINE void
-overwritingMutableClosureOfs (StgClosure *p, uint32_t offset)
+void stg_overwritingMutableClosureOfs (StgClosure *p, uint32_t offset);
+INLINE_HEADER void overwritingMutableClosureOfs (StgClosure *p, uint32_t offset)
{
// Since overwritingClosureOfs is only ever called by:
//
@@ -610,8 +605,8 @@ overwritingMutableClosureOfs (StgClosure *p, uint32_t offset)
}
// Version of 'overwritingClosure' which takes closure size as argument.
-EXTERN_INLINE void overwritingClosureSize (StgClosure *p, uint32_t size /* in words */);
-EXTERN_INLINE void overwritingClosureSize (StgClosure *p, uint32_t size)
+void stg_OverwritingClosureSize (StgClosure *p, uint32_t size /* in words */);
+INLINE_HEADER void overwritingClosureSize (StgClosure *p, uint32_t size)
{
// This function is only called from stg_AP_STACK so we can assume it's not
// inherently used.
=====================================
rts/rts.cabal.in
=====================================
@@ -603,6 +603,7 @@ library
TSANUtils.c
WSDeque.c
Weak.c
+ ZeroSlop.c
eventlog/EventLog.c
eventlog/EventLogWriter.c
hooks/FlagDefaults.c
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/4028e7fabc2574e96116919d528cbfc77b403053...25422c95aaed438cfaf0cccf02c634ecdd6e73f1
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/4028e7fabc2574e96116919d528cbfc77b403053...25422c95aaed438cfaf0cccf02c634ecdd6e73f1
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