Data race with state field of ThreadPoolElement

Host environment

• Operating system: Ubuntu Linux

Description of problem

A data race in the access of ThreadPoolElement state field in util/thread-pool.c was identified using TSAN.

Steps to reproduce

QEMU_BUILD_DIR=<path to the QEMU build directory>
QEMU_DIR=<path to the QEMU repository directory>
configure --enable-tsan --cc=clang --cxx=clang++ --enable-trace-backends=ust --enable-fdt=system --disable-slirp
make tests/unit/test-thread-pool
MALLOC_PERTURB_=111 G_TEST_SRCDIR=$QEMU_BUILD_DIR/tests/unit G_TEST_BUILDDIR=$QEMU_BUILD_DIR/tests/unit $QEMU_BUILD_DIR/tests/unit/test-thread-pool --tap -k

Log

WARNING: ThreadSanitizer: data race (pid=787043)
  Write of size 4 at 0x7b1c00000660 by thread T5 (mutexes: write M0):
    #0 worker_thread /home/mordan/qemu/build/../util/thread-pool.c:108:20 (test-thread-pool-smc+0xa65a56)
    #1 qemu_thread_start /home/mordan/qemu/build/../util/qemu-thread-posix.c:543:9 (test-thread-pool-smc+0xa49040)

  Previous read of size 4 at 0x7b1c00000660 by main thread:
    #0 thread_pool_completion_bh /home/mordan/qemu/build/../util/thread-pool.c:183:19 (test-thread-pool-smc+0xa6549d)
    #1 aio_bh_call /home/mordan/qemu/build/../util/async.c:171:5 (test-thread-pool-smc+0xa5e03e)
    #2 aio_bh_poll /home/mordan/qemu/build/../util/async.c:218:13 (test-thread-pool-smc+0xa5e03e)
    #3 aio_poll /home/mordan/qemu/build/../util/aio-posix.c:722:17 (test-thread-pool-smc+0xa4343a)
    #4 test_submit_many /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:133:9 (test-thread-pool-smc+0x50e638)
    #5 do_test_cancel /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:150:5 (test-thread-pool-smc+0x50e638)
    #6 test_cancel_async /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:234:5 (test-thread-pool-smc+0x50e638)
    #7 main /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:249:3 (test-thread-pool-smc+0x50e638)

  Location is heap block of size 104 at 0x7b1c00000620 allocated by main thread:
    #0 malloc out/lib/clangrt-x86_64-unknown-linux-gnu/./out/lib/clangrt-x86_64-unknown-linux-gnu/./toolchain/llvm-project/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:667:5 (test-thread-pool-smc+0x346131)
    #1 g_malloc <null> (libglib-2.0.so.0+0x5e738) (BuildId: e845b8fd2f396872c036976626389ffc4f50c9c5)
    #2 thread_pool_submit_aio /home/mordan/qemu/build/../util/thread-pool.c:251:11 (test-thread-pool-smc+0xa648bd)
    #3 test_submit_many /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:128:9 (test-thread-pool-smc+0x50e600)
    #4 do_test_cancel /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:150:5 (test-thread-pool-smc+0x50e600)
    #5 test_cancel_async /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:234:5 (test-thread-pool-smc+0x50e600)
    #6 main /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:249:3 (test-thread-pool-smc+0x50e600)

  Mutex M0 (0x7b3c00000100) created at:
    #0 pthread_mutex_init out/lib/clangrt-x86_64-unknown-linux-gnu/./out/lib/clangrt-x86_64-unknown-linux-gnu/./toolchain/llvm-project/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:1316:3 (test-thread-pool-smc+0x34914f)
    #1 qemu_mutex_init /home/mordan/qemu/build/../util/qemu-thread-posix.c:71:11 (test-thread-pool-smc+0xa47189)
    #2 thread_pool_init_one /home/mordan/qemu/build/../util/thread-pool.c:334:5 (test-thread-pool-smc+0xa64f60)
    #3 thread_pool_new /home/mordan/qemu/build/../util/thread-pool.c:348:5 (test-thread-pool-smc+0xa64f60)
    #4 aio_get_thread_pool /home/mordan/qemu/build/../util/async.c:441:28 (test-thread-pool-smc+0xa5e6d4)
    #5 thread_pool_submit_aio /home/mordan/qemu/build/../util/thread-pool.c:246:24 (test-thread-pool-smc+0xa6488d)
    #6 test_submit_many /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:128:9 (test-thread-pool-smc+0x50e600)
    #7 do_test_cancel /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:150:5 (test-thread-pool-smc+0x50e600)
    #8 test_cancel_async /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:234:5 (test-thread-pool-smc+0x50e600)
    #9 main /home/mordan/qemu/build/../tests/unit/test-thread-pool-smc.c:249:3 (test-thread-pool-smc+0x50e600)

  Thread T5 'worker' (tid=787049, running) created by thread T4 at:
    #0 pthread_create out/lib/clangrt-x86_64-unknown-linux-gnu/./out/lib/clangrt-x86_64-unknown-linux-gnu/./toolchain/llvm-project/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:1022:3 (test-thread-pool-smc+0x34791d)
    #1 qemu_thread_create /home/mordan/qemu/build/../util/qemu-thread-posix.c:583:11 (test-thread-pool-smc+0xa48ed0)
    #2 do_spawn_thread /home/mordan/qemu/build/../util/thread-pool.c:146:5 (test-thread-pool-smc+0xa658de)
    #3 worker_thread /home/mordan/qemu/build/../util/thread-pool.c:83:5 (test-thread-pool-smc+0xa658de)
    #4 qemu_thread_start /home/mordan/qemu/build/../util/qemu-thread-posix.c:543:9 (test-thread-pool-smc+0xa49040)

SUMMARY: ThreadSanitizer: data race /home/mordan/qemu/build/../util/thread-pool.c:108:20 in worker_thread