RE: [PATCH] sparc: make copy_thread honor pid namespaces

[David Laight]

From: Dmitry V. Levin
> Sent: 17 February 2021 08:00
> 
> On sparc, fork and clone syscalls have an unusual semantics of
> returning the pid of the parent process to the child process.

Isn't that just broken?
The application expects fork() to return 0 in the child.
libc would have to do horrid things to convert the result.

It could be comparing against the saved 'current pid' in
order to save a system call for the first ppid() call.
But that isn't ever going to work if it is possible to
create a child in a different pid namespace.

FWIW the test program ought to use syscall() to get the pid
and ppid - rather than relying on any optimisations in libc.

	David

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