Re: [PATCH] kernel: add a kernel_wait helper

[Christoph Hellwig]

On Tue, Jul 21, 2020 at 02:18:38PM -0700, Andrew Morton wrote:
> On Tue, 21 Jul 2020 15:04:49 +0200 Christoph Hellwig <hch@xxxxxx> wrote:
> 
> > Add a helper that waits for a pid and stores the status in the passed
> > in kernel pointer.  Use it to fix the usage of kernel_wait4 in
> > call_usermodehelper_exec_sync that only happens to work due to the
> > implicit set_fs(KERNEL_DS) for kernel threads.
> 
> I guess it's cleaner, although it's a bit sad to be adding code to
> address a non-problem.
> 
> Did you consider a simpler kernel_wait() which just wraps a
> set_fs(KERNEL_DS) around a call to kernel_wait4()?

I'm about to kill set_fs and this one of the last users in linux-next..