Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals.

[Anthony Liguori <anthony@xxxxxxxxxxxxx>]

Ian Jackson wrote:
> Jamie Lokier writes ("Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle 
> terminating signals."):
>   
> > A quick read of Glibc 2.3.1 source says its AIO code does not change
> > the signal mask when it creates an AIO handling thread.
> >     
> Thanks for investigating that.
>
>   
> > (This might be a Glibc bug - threads you don't know about shouldn't be
> > receiving your signals, should they?)
> >     
> Yes, it's a bug.  (I wonder why my test program didn't expose it.)
>
>   
> > That means if it wasn't masked when you issued the first AIO request,
> > it won't be masked in that thread.
> >     
> In practice since we use aio this probably means we can't rely on
> signal blocking except for signals which qemu keeps blocked `nearly
> all' the time.  So pipe-to-self in the signal handler is the way to
> go.
>   
In my signalfd patch, we block SIGUSR2 all the time so it shouldn't be 
affected by this "bug".  We use sigwait or signalfd to receive the signal.
Regards,

Anthony Liguori


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