This patch series solves the coroutines TLS problem. Coroutines re-entered from another thread sometimes see stale TLS values. This happens because compilers may cache values across yield points, so a value from the previous thread will be used when the coroutine is re-entered in another thread.
Serge Guelton developed a portable technique and Richard Henderson developed an inline-friendly architecture-specific technique, see the first patch for details. I have audited all __thread variables in QEMU and converted those that can be used from coroutines. Most actually look safe to me. This patch does not include a checkpatch.pl rule that requires coroutine-tls.h usage, but perhaps we should add one for block/ at least? Stefan Hajnoczi (4): tls: add macros for coroutine-safe TLS variables util/async: replace __thread with QEMU TLS macros rcu: use coroutine TLS macros cpus: use coroutine TLS macros for iothread_locked include/qemu/coroutine-tls.h | 202 +++++++++++++++++++++++++++++++++++ include/qemu/rcu.h | 7 +- softmmu/cpus.c | 8 +- tests/unit/rcutorture.c | 10 +- tests/unit/test-rcu-list.c | 4 +- util/async.c | 12 ++- util/rcu.c | 10 +- 7 files changed, 229 insertions(+), 24 deletions(-) create mode 100644 include/qemu/coroutine-tls.h -- 2.33.1
