Re: [patch] threading enhancements, tid-2.5.47-C0

[Ulrich Drepper <drepper@redhat.com>]

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Jamie Lokier wrote:

> This is "int cfork(pid_t * user_tid_ptr)", yes?  I've searched google for
> cfork and not found anything fruitful - just references to solaris
> patches about a function of the same name.

It's just a coincident.  I made the name up and there is no function
like that so far, at least as far I know.


> Then yes, you need two pointers, one for the parent's cfork() argument
> for SETTID in the parent, and one for the child's thread descriptor
> for CLEARTID in the child.  Strictly speaking, SETTID does not need to
> affect the child (because the child can store the tid itself), but it
> would make a lot of sense to do it.

The CHILD_SETTID is needed, too, since otherwise the PID isn't stored in
the child's thread descriptor.


> (That said, I'm not entirely convinced that blocking signals in cfork()
> is so bad, if we assume that cfork() is a relatively expensive
> operation anyway...)

It could mean a signal cannot be delivered and reacted on in time.  The
other threads could have blocked the signal which arrives.  Every time
signals have to be blocked to implement a function something is wrong,

- -- 
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