Michał Chojnowski bd301a418b [BOLT] Fix concurrent hash table modification in the instrumentation runtime ...

`__bolt_instr_data_dump()` does not lock the hash tables when iterating
over them, so the iteration can happen concurrently with a modification
done in another thread, when the table is in an inconsistent state. This
also has been observed in practice, when it caused a segmentation fault.

We fix this by locking hash tables during iteration. This is done by taking
the lock in `forEachElement()`.
The only other site of iteration, `resetCounters()`, has been correctly
locking the table even before this patch. This patch removes its `Lock`
because the lock is now taken in the inner `forEachElement()`.

Reviewed By: maksfb, yota9

Differential Revision: https://reviews.llvm.org/D129089

2022-07-07 14:27:29 +03:00

59 KiB

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