v5: - Added explicit "#include "qemu/coroutine-tls.h" in patch 4 [Philippe] - Updated patch 1 commit description and comments to describe the current noinline plus asm volatile approach [Peter] v4: - Dropped '[RFC]'. - Dropped inline asm for now. -fPIC versions of the code are missing and I hit several issues including a clang LTO bug where thread local variables are incorrectly discarded because inline asm is not analyzed to find symbol dependencies (Serge Guelton is aware). - Fixed CI failures. v3: - Added __attribute__((weak)) to get_ptr_*() [Florian] - Replace rdfsbase with mov %%fs:0,%0 [Florian]
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, 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. 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 | 165 +++++++++++++++++++++++++++++++++++ include/qemu/rcu.h | 7 +- softmmu/cpus.c | 9 +- tests/unit/rcutorture.c | 10 +-- tests/unit/test-rcu-list.c | 4 +- util/async.c | 12 +-- util/rcu.c | 10 +-- 7 files changed, 193 insertions(+), 24 deletions(-) create mode 100644 include/qemu/coroutine-tls.h -- 2.34.1
