[RFC 0/2] tls: add macros for coroutine-safe TLS variables

[Stefan Hajnoczi <stefanha@redhat.com>]

This is a preview of how we can solve 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 this technique, see the first patch for details. I'm
submitting it for discussion before I go ahead with a full conversion of the
source tree.

Todo:
- Convert all uses of __thread
- Extend checkpatch.pl to reject code that uses __thread

Stefan Hajnoczi (2):
  tls: add macros for coroutine-safe TLS variables
  util/async: replace __thread with QEMU TLS macros

 MAINTAINERS        |   1 +
 include/qemu/tls.h | 142 +++++++++++++++++++++++++++++++++++++++++++++
 util/async.c       |  12 ++--
 3 files changed, 150 insertions(+), 5 deletions(-)
 create mode 100644 include/qemu/tls.h

-- 
2.31.1