The Lost Atomic Update on Loongson CPU

Automated excerpt

However, testing the atomicity of the atomic add instruction with a simple atomic add program could not reproduce the lost update. After discovering that the atomic add instruction can lose updates, we had new questions: first, is only atomic add affected, or do other atomic instructions have the same problem; second, do other memory operations also trigger similar problems. For other atomic instructions, such as atomic swap, atomic max, atomic min, atomic bitwise AND, atomic bitwise OR, and so on, since even a lost update is not easy to detect from the result, we did not verify them at first.

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