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Re: [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall
From: |
Riku Voipio |
Subject: |
Re: [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall |
Date: |
Wed, 6 May 2009 15:02:56 +0300 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Wed, May 06, 2009 at 12:08:32PM +0100, Jamie Lokier wrote:
> But it's not a bug to call execve(), or fork() then execve(), in
> another thread at the same time as descriptors are being created.
> Those calls scan the whole file descriptor table, and look at the
> FD_CLOEXEC flags.
Now this discussion would be much more useful if qemu was actually
properly threadsafe to begin with...
> I haven't looked too closely at how guest file descriptors are handled
> in QEMU these days. In an older version I'm looking at, guest file
> descriptors are simply host file descriptors so the pipe2 emulation is
> broken in this way.
> If QEMU maintained a guest file descriptor table internally, emulating
> what a kernel does, this would be solved automatically, but it doesn't.
> You can solve it quite simply for any host kernel with the lock
> solution I just posted in another mail on this thread. The same
> method works for all the other syscalls taking *_CLOEXEC flags, so
> it's probably a good idea :-)
Either of these suggested changes are separate new features, and
would thus need to be implemented as separate patches. Thanks
for patches in advance :-)
- [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall, Riku Voipio, 2009/05/05
- [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall [v2], Riku Voipio, 2009/05/05
- Re: [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall, Jamie Lokier, 2009/05/05
- Re: [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall, Riku Voipio, 2009/05/06
- Re: [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall, Jamie Lokier, 2009/05/06
- Re: [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall,
Riku Voipio <=
- Re: [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall, Martin Mohring, 2009/05/06
- Re: [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall, Paul Brook, 2009/05/06
- Re: [Qemu-devel] [PATCH] linux-user: implement pipe2 syscall, Riku Voipio, 2009/05/06