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From: Paolo Bonzini <pbonzini@redhat.com>
To: Laszlo Ersek <lersek@redhat.com>, Max Reitz <mreitz@redhat.com>,
	qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [PATCH] coroutine-sigaltstack: Keep SIGUSR2 handler up
Date: Sat, 23 Jan 2021 23:13:09 +0100	[thread overview]
Message-ID: <063dd2a6-a3ae-0d7c-3e29-96a08a6d9a3d@redhat.com> (raw)
In-Reply-To: <cba8919b-0480-3520-6ad6-920bf9d4186e@redhat.com>

On 22/01/21 22:26, Laszlo Ersek wrote:
> That seems bogus, per POSIX, given that all signals except SIGUSR2 are
> included in the mask passed to sigsuspend().

What happens if you get a SIGSTOP at exactly the wrong time?  (Yeah I 
know how incredibly unlikely that would be).

BTW if we are in a mood for cleanup, there's no reason to use 
pthread_key_t instead of __thread + qemu_thread_atexit_add (adding a 
Notifier to struct CoroutineThreadState).  That would fix the issue with 
async-signal safety of pthread_getspecific.

(It makes sense for the function not to be async-signal safe since it 
can in principle allocate memory for the data.  In practice it's most 
likely okay if the function has been called before on this thread).

Paolo



  parent reply	other threads:[~2021-01-23 22:14 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-22 10:20 [PATCH] coroutine-sigaltstack: Keep SIGUSR2 handler up Max Reitz
2021-01-22 14:55 ` Eric Blake
2021-01-22 16:38 ` Laszlo Ersek
2021-01-22 17:58   ` Max Reitz
2021-01-22 18:19     ` Eric Blake
2021-01-22 18:28       ` Laszlo Ersek
2021-01-22 18:27     ` Laszlo Ersek
2021-01-22 19:02     ` Laszlo Ersek
2021-01-22 17:09 ` Laszlo Ersek
2021-01-22 18:05   ` Max Reitz
2021-01-22 18:29     ` Laszlo Ersek
2021-01-22 21:26       ` Laszlo Ersek
2021-01-23  0:41         ` Laszlo Ersek
2021-01-25 10:57           ` Max Reitz
2021-01-25 21:16             ` Laszlo Ersek
2021-01-23 22:13         ` Paolo Bonzini [this message]
2021-01-25 21:13           ` Laszlo Ersek
2021-01-25 22:08             ` Laszlo Ersek

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