On Wed, 20 Aug 2025 17:31:22 GMT, Evgeny Astigeevich <eastigeev...@openjdk.org> wrote:
>> There is a race between `JvmtiClassFileReconstituter::copy_bytecodes` and >> `InstanceKlass::link_class_impl`. `InstanceKlass::link_class_impl` can be >> rewriting bytecodes. `JvmtiClassFileReconstituter::copy_bytecodes` will not >> restore them to the original ones because the flag `rewritten` is `false`. >> This will result in invalid bytecode. >> >> This PR adds a lock (`init_lock`) to the `copy_bytecodes` method to prevent >> reading bytecodes while they are being rewritten during class linking. >> >> Tested fastdebug and release builds: Linux x86_64 and arm64 >> - The reproducer from JDK-8277444 passed. >> - Tier1 - tier3 passed. > > Evgeny Astigeevich has updated the pull request incrementally with one > additional commit since the last revision: > > Add missing include runtime/synchronizer.hpp src/hotspot/share/prims/jvmtiClassFileReconstituter.cpp line 1004: > 1002: // is_rewritten() returns false. So we won't restore the original > bytecodes. > 1003: // We hold a lock to guarantee we are not getting bytecodes > 1004: // at the same time the linking process are rewriting them. Suggestion: // We acquire the init_lock monitor to serialize with class linking so we are not getting // bytecodes at the same time the linking process is rewriting them. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/26863#discussion_r2299044927
