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From: Max Reitz <mreitz@redhat.com>
To: Laszlo Ersek <lersek@redhat.com>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: Thread safety of coroutine-sigaltstack
Date: Fri, 22 Jan 2021 09:48:07 +0100	[thread overview]
Message-ID: <fc35da77-a5c2-08dd-05f2-0ebe781b338c@redhat.com> (raw)
In-Reply-To: <445268c9-d91f-af5a-3d7e-f4c6f014ca52@redhat.com>

On 20.01.21 18:25, Laszlo Ersek wrote:

[...]

> A simple grep for SIGUSR2 seems to indicate that SIGUSR2 is not used by
> system emulation for anything else, in practice. Is it possible to
> dedicate SIGUSR2 explicitly to coroutine-sigaltstack, and set up the
> action beforehand, from some init function that executes on a "central"
> thread, before qemu_coroutine_new() is ever called?

I wrote a patch to that effect, but just before sending I wondered 
whether SIGUSR2 cannot be registered by the “guest” in user-mode 
emulation, and whether that would then break coroutines from there on.

(I have no experience dealing with user-mode emulation, but it does look 
like the guest can just register handlers for any signal but SIGSEGV and 
SIGBUS.)

Max



  parent reply	other threads:[~2021-01-22  8:49 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-20 16:26 Thread safety of coroutine-sigaltstack Max Reitz
2021-01-20 16:50 ` Paolo Bonzini
2021-01-20 16:58 ` Eric Blake
2021-01-20 17:25 ` Laszlo Ersek
2021-01-21  9:27   ` Max Reitz
2021-01-21 13:34     ` Laszlo Ersek
2021-01-21 15:42       ` Max Reitz
2021-01-21 16:04         ` Daniel P. Berrangé
2021-01-21 16:05         ` Laszlo Ersek
2021-01-21 15:14     ` Paolo Bonzini
2021-01-21 16:07       ` Daniel P. Berrangé
2021-01-21 16:44         ` Peter Maydell
2021-01-21 17:24           ` Paolo Bonzini
2021-01-22 20:38             ` Laszlo Ersek
2021-01-22 21:34               ` Laszlo Ersek
2021-01-22 21:41                 ` Laszlo Ersek
2021-01-22  7:55       ` Markus Armbruster
2021-01-22  8:48   ` Max Reitz [this message]
2021-01-22 10:14     ` Peter Maydell
2021-01-22 10:16       ` Max Reitz
2021-01-22 12:24       ` Laszlo Ersek
2021-01-23  0:06       ` Laszlo Ersek
2021-01-23 13:35         ` Peter Maydell
2021-01-25 22:15           ` Laszlo Ersek
2021-01-25 22:45             ` Paolo Bonzini
2021-01-26  8:57               ` Laszlo Ersek

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