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[RFC v2 0/4] tls: add macros for coroutine-safe TLS variables
From: |
Stefan Hajnoczi |
Subject: |
[RFC v2 0/4] tls: add macros for coroutine-safe TLS variables |
Date: |
Wed, 1 Dec 2021 17:01:16 +0000 |
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
- [RFC v2 0/4] tls: add macros for coroutine-safe TLS variables,
Stefan Hajnoczi <=