From: Stefan Hajnoczi <stefanha@redhat.com>
To: qemu-devel@nongnu.org
Cc: fweimer@redhat.com, Kevin Wolf <kwolf@redhat.com>,
thuth@redhat.com, qemu-block@nongnu.org,
Stefan Hajnoczi <stefanha@redhat.com>, Fam Zheng <fam@euphon.net>,
sguelton@redhat.com
Subject: [RFC 0/2] tls: add macros for coroutine-safe TLS variables
Date: Mon, 25 Oct 2021 15:07:14 +0100 [thread overview]
Message-ID: <20211025140716.166971-1-stefanha@redhat.com> (raw)
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
next reply other threads:[~2021-10-25 14:09 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-25 14:07 Stefan Hajnoczi [this message]
2021-10-25 14:07 ` [RFC 1/2] tls: add macros for coroutine-safe TLS variables Stefan Hajnoczi
2021-10-25 14:14 ` Daniel P. Berrangé
2021-10-26 13:36 ` Stefan Hajnoczi
2021-10-26 13:41 ` Stefan Hajnoczi
2021-10-26 14:10 ` Kevin Wolf
2021-10-26 16:26 ` Stefan Hajnoczi
2021-10-25 17:19 ` Richard Henderson
2021-10-26 13:30 ` Stefan Hajnoczi
2021-10-26 15:32 ` Richard Henderson
2021-10-26 16:27 ` Stefan Hajnoczi
2021-10-25 14:07 ` [RFC 2/2] util/async: replace __thread with QEMU TLS macros Stefan Hajnoczi
2021-10-25 14:20 ` [RFC 0/2] tls: add macros for coroutine-safe TLS variables Philippe Mathieu-Daudé
2021-10-25 16:16 ` Richard Henderson
2021-10-25 23:27 ` Warner Losh
2021-10-26 13:22 ` Stefan Hajnoczi
2021-10-26 15:10 ` Richard Henderson
2021-10-26 16:34 ` Stefan Hajnoczi
2021-10-26 17:10 ` Richard Henderson
2021-10-26 17:26 ` Thomas Huth
2021-10-26 18:03 ` Richard Henderson
2021-10-27 10:38 ` Kevin Wolf
2021-10-27 12:34 ` Stefan Hajnoczi
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