diff options
| -rw-r--r-- | compiler-rt/lib/scudo/scudo_allocator.cpp | 15 |
1 files changed, 5 insertions, 10 deletions
diff --git a/compiler-rt/lib/scudo/scudo_allocator.cpp b/compiler-rt/lib/scudo/scudo_allocator.cpp index df91fdc80cf..fb04fb281c4 100644 --- a/compiler-rt/lib/scudo/scudo_allocator.cpp +++ b/compiler-rt/lib/scudo/scudo_allocator.cpp @@ -129,16 +129,9 @@ namespace Chunk { computeChecksum(Ptr, &NewUnpackedHeader)); } - // Nulls out a chunk header. When returning the chunk to the backend, there - // is no need to store a valid ChunkAvailable header, as this would be - // computationally expensive. Zeroing out serves the same purpose by making - // the header invalid. In the extremely rare event where 0 would be a valid - // checksum for the chunk, the state of the chunk is ChunkAvailable anyway. + // Ensure that ChunkAvailable is 0, so that if a 0 checksum is ever valid + // for a fully nulled out header, its state will be available anyway. COMPILER_CHECK(ChunkAvailable == 0); - static INLINE void eraseHeader(void *Ptr) { - const PackedHeader NullPackedHeader = 0; - atomic_store_relaxed(getAtomicHeader(Ptr), NullPackedHeader); - } // Loads and unpacks the header, verifying the checksum in the process. static INLINE @@ -185,7 +178,9 @@ struct QuarantineCallback { Chunk::loadHeader(Ptr, &Header); if (UNLIKELY(Header.State != ChunkQuarantine)) dieWithMessage("invalid chunk state when recycling address %p\n", Ptr); - Chunk::eraseHeader(Ptr); + UnpackedHeader NewHeader = Header; + NewHeader.State = ChunkAvailable; + Chunk::compareExchangeHeader(Ptr, &NewHeader, &Header); void *BackendPtr = Chunk::getBackendPtr(Ptr, &Header); if (Header.ClassId) getBackend().deallocatePrimary(Cache_, BackendPtr, Header.ClassId); |
