From: Stefan Hajnoczi <stefanha@redhat.com>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: fweimer@redhat.com, Kevin Wolf <kwolf@redhat.com>,
Thomas Huth <thuth@redhat.com>,
"open list:Block layer core" <qemu-block@nongnu.org>,
QEMU Developers <qemu-devel@nongnu.org>,
Fam Zheng <fam@euphon.net>, Warner Losh <imp@bsdimp.com>,
sguelton@redhat.com
Subject: Re: [RFC 0/2] tls: add macros for coroutine-safe TLS variables
Date: Tue, 26 Oct 2021 17:34:26 +0100 [thread overview]
Message-ID: <YXguEo8UQUX/cRo9@stefanha-x1.localdomain> (raw)
In-Reply-To: <85df7de0-cebb-efe9-d26b-f459a37a6621@linaro.org>
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On Tue, Oct 26, 2021 at 08:10:16AM -0700, Richard Henderson wrote:
> On 10/26/21 6:22 AM, Stefan Hajnoczi wrote:
> > If "safe" TLS variables are opt-in then we'll likely have obscure bugs
> > when code changes to access a TLS variable that was previously never
> > accessed from a coroutine. There is no compiler error and no way to
> > detect this. When it happens debugging it is painful.
>
> Co-routines are never used in user-only builds.
If developers have the choice of using __thread then bugs can slip
through.
Your assembly get_addr() approach reduces the performance overhead of
TLS getters/setters.
Are you concerned about performance, the awkwardness of calling
getters/setters, or something else for qemu-user?
Stefan
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next prev parent reply other threads:[~2021-10-26 16:40 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-25 14:07 [RFC 0/2] tls: add macros for coroutine-safe TLS variables Stefan Hajnoczi
2021-10-25 14:07 ` [RFC 1/2] " 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 [this message]
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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