Re: vfork
Linus Torvalds (torvalds@transmeta.com)
29 Dec 1999 11:35:23 -0800
In article <87902fzd45.fsf@kc.net>, Mike Coleman <mkc@kc.net> wrote:
>Wichert Akkerman <wakkerma@debian.org> writes:
>> I started a bit on adding support for tracing clone() in strace. I have
>> the basic framework in place, the only thing I need to do if I'm not
>> mistaken is modify the clone flags to add CLONE_PTRACE. I haven't had
>> the time to figure out how do to that yet..
>
>I've been looking at this too (for a tool I'll release Real Soon Now), and
>I've run across a few more things that seem to need tweaking.
>
>The tracer (e.g., strace) needs to be able to wait on clone and non-clone kids
>at the same time, but the current __WCLONE doesn't allow this. The change to
>exit.c below changes its semantics to make it wait for all kids. (I wonder if
>any existing software depends on the old semantics. We could always add a new
>flag instead.)
Add another flag.. Alternatively, the tracer could always do something
like this with the current __WCLONE semantics:
if (wait4(..normal..) >= 0 || wait4(.. __WCLONE ..) >= 0) {
...
}
In either case this is not a wart big enough to break existing behaviour
(especially as the __WCLONE behaviour actually makes sense - libraries
that want to wait on non-regular children _only_ want to use the current
__WCLONE behaviour, which allows them to not ever catch a "normal" child
by mistake..)
Linus
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