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From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] rework daemonizing logic in qemu-nbd
Date: Sun, 15 Jan 2012 18:46:48 +0100	[thread overview]
Message-ID: <jev3e8$444$1@dough.gmane.org> (raw)
In-Reply-To: <4F130D78.1070903@redhat.com>

On 01/15/2012 06:31 PM, Paolo Bonzini wrote:
>
>
>> We're doomed anyway, and it is even good
>> we've a small remote chance for our error message to
>> be seen.  Currently it just goes to /dev/null.
>
> No, currently it is sent from the daemon to the parent through the pipe,
> the parent prints it and exits with status code 1.  With your patch, if
> the dup2 wins the race you exit with status code 0; if the client thread
> wins the race it is the same as master.

Actually, the dup2 will always win the race.  Until the main loop starts 
and accepts the connection from the client thread, the client thread 
will be stuck connect()ing to the server socket.  So, the client thread 
will never be able to report problems connecting /dev/nbd (for example 
you won't get an error if you chose a device that is already busy).  So 
it looks like there is no race, but there is a bug. :)

Please disprove me if I'm wrong, of course.

Paolo

  reply	other threads:[~2012-01-15 17:47 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-14 12:39 [Qemu-devel] [PATCH] rework daemonizing logic in qemu-nbd Michael Tokarev
2012-01-15 10:42 ` Paolo Bonzini
2012-01-15 12:50   ` Michael Tokarev
2012-01-15 16:11     ` Paolo Bonzini
2012-01-15 16:44       ` Michael Tokarev
2012-01-15 17:31         ` Paolo Bonzini
2012-01-15 17:46           ` Paolo Bonzini [this message]
2012-01-16  7:22           ` Michael Tokarev
2012-01-16  7:41             ` Paolo Bonzini

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