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Re: [Xen-devel] [PATCH] libxl: check pending child signals on libxl__ev_child_inuse

Roger Pau Monne writes ("Re: [Xen-devel] [PATCH] libxl: check pending child 
signals on libxl__ev_child_inuse"):
> Subject: [PATCH] libxl: react correctly to POLLHUP
> On datacopier_readable ignore PULLHUP, since we will shortly process
> the death of the underlying process.

Again, I don't think this is correct.

> Since this is also prone to races, we should ignore POLLHUP on 
> datacopier_readable and wait for the underlying process (the bootloader 
> in this case) to exit. Linux probably doesn't send a POLLHUP when the 
> process on the other end of the pty dies, but NetBSD does so, and since 
> we process the fd events first we should ignore this and expect that the 
> process dies.

You are assuming that the POLLHUP necessarily means the bootloader
process is going to die.  But perhaps it has gone mad and isn't going
to do so.  That's why we need to send it a SIGKILL.


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