From: Kevin Wolf <kwolf@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: fweimer@redhat.com, "Fam Zheng" <fam@euphon.net>,
thuth@redhat.com, "Daniel P. Berrangé" <berrange@redhat.com>,
qemu-block@nongnu.org, qemu-devel@nongnu.org,
sguelton@redhat.com
Subject: Re: [RFC 1/2] tls: add macros for coroutine-safe TLS variables
Date: Tue, 26 Oct 2021 16:10:16 +0200 [thread overview]
Message-ID: <YXgMSFJhfE6mdVIq@redhat.com> (raw)
In-Reply-To: <YXgFg0aHtvXNorUS@stefanha-x1.localdomain>
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Am 26.10.2021 um 15:41 hat Stefan Hajnoczi geschrieben:
> Actually, nevermind what I said about the callback scenario. I don't
> think that is a problem because the compiler cannot assume the __thread
> variable remains unchanged across the callback. Therefore it cannot
> safely cache the value.
And additionally, I think callbacks are never coroutine_fn (especially
not if they come from an external library), so they must not yield
anyway.
> So I think only the header file scenario is a problem.
The mere existence of a __thread variable in the header file isn't a
problem either, but if QEMU accesses it, we would have to implement
wrappers similar to what you're proposing for QEMU's thread local
variables.
Kevin
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next prev parent reply other threads:[~2021-10-26 14:12 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 [this message]
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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