Re: [PATCH] ptrace on stopped processes (2.4)

[Werner Almesberger <wa@almesberger.net>]

Daniel Jacobowitz wrote:
> Have you got an example that needs this?

No, I was just suggesting an approach that may work, in case
somebody wants to fix this. SIGSTOP/CONT doesn't seem like a
very popular communication mechanism anyway.

I did notice that two processes trying to ptrace each other
end up being unkillably deadlocked on 2.4.18, which a fix
for the SIGSTOP problem may resolve, but I didn't check if
this still happens in more recent kernels. ("Don't do it" is
a satisfactory work-around.)

I'll worry about such subtleties once I've made heads and
tails of how UML's ptrace-relay interacts with process
termination :-)

- Werner

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 / Werner Almesberger, Buenos Aires, Argentina         wa@almesberger.net /
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