Fix a rare crash in the garbage collector while restoring a workspace #5371
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fingolfin
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Feb 7, 2023
| @@ -388,8 +388,14 @@ void CHANGED_BAG(Bag b); | |||
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| extern Bag * YoungBags; | |||
| extern Bag ChangedBags; | |||
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| #ifdef GAP_KERNEL_DEBUG | |||
| BOOL InWorkspaceRestore(void); | |||
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| BOOL InWorkspaceRestore(void); | |
| BOOL InWorkspaceRestore(void); |
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The place where I've put it is where clang-format wants to put it (I guess to line us with the variables above?), so I'd prefer to leave it there, else it might just move in future if we ever clang-format everything.
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Makes sense. I thought it would be the other way around
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Now (hopefully) all fixed up |
fingolfin
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Feb 8, 2023
src/objset.c
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| AddObjMapNew(new, obj, | ||
| READ_SLOT(map, i*2+1)); | ||
| AddObjMapNew(new, obj, READ_SLOT(map, i * 2 + 1)); | ||
| CHANGED_BAG(new); |
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This is not needed as no GC can occur in this loop, and afterwards SwapMasterPointer ensures both bags are marked aa changed (so the two CHANGED_BAG calls after it could also go)
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fingolfin
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Feb 8, 2023
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While we are loading a workspace, gasman is kept in a slightly-inconsistent state, with various pointers only set at the end. This means we mustn't call functions like NewBag, ResizeBag and (the problem we were hitting, subtly), CHANGED_BAG.
This stops objset/objmap from calling CHANGED_BAG, and adds asserts to make sure this doesn't happen again in future (and verifies nothing else is calling any of these methods).