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Re: [Qemu-devel] [PATCH 00/34] linux-user: Fix signal race conditions an
From: |
Riku Voipio |
Subject: |
Re: [Qemu-devel] [PATCH 00/34] linux-user: Fix signal race conditions and SA_RESTART |
Date: |
Fri, 2 Oct 2015 14:52:44 +0300 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
Hi Timothy,
On Thu, Sep 10, 2015 at 07:00:18PM +0100, Peter Maydell wrote:
> On 6 September 2015 at 00:56, Timothy E Baldwin
> <address@hidden> wrote:
> > There are many races with signals in linux user:
> >
> > - Multiple host signals in quick succession, fixed by keeping host signals
> > blocked, and checking if target signals are blocked before calling
> > target signal handler.
> > - Signal shortly before blocking system call, fixed by either:
> > - Block hosts signals, check and use host system call with
> > sigset_t parameter.
> > - Or check if signals are pending immediately before host system call
> > and if a signal arrives between the check and system call rewind
> > host instruction pointer to before the check. Also fixes SA_RESTART.
> > - Signal before or during sensitive system call, fixed in a similar manner.
> > - Close host and synchronous signals, partly fixed by implementing a
> > separate
> > queue for synchronous signals which are dispatched first. The
> > asynchronous
> > signal may still be delayed or lost rather than dispatched to another
> > thread
> > or handled after exec().
> >
> > Also fixed:
> > - Errno array bounds.
> > - Default fatal actions occurring in the middle of target instructions.
>
> Thanks for sending this patchset. This is really cool and we've needed
> it for a long time...
Indeed, this would be nice to have for Qemu 2.5. Do you have time to
work through Peters comments and send an updated round of patches?
Riku
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Riku Voipio <=