[RFC][PATCH 1/4][cr]: Add uid, euid params to f_modown()

[Jamie Lokier]

Sukadev Bhattiprolu wrote:
> Checkpoint/restart of file-owner.
> 
> Add uid, euid parameters to f_modown(). These parameters will be needed
> when restarting an application (and hence restoring the file information),
> from a checkpoint image.

This is used to make sure I/O signals on sockets, ttys, devices and so
on are delivered to a particular process.

If any of those signals are lost when an event happens around the same
time as c/r (for example, more data arriving on a pipe, a device
becomes readable/writable, or room becoming available to write, or
urgent data on a socket), a process depending on it can get stuck -
unless the process knows that c/r happened, so it knows to call
select() on all those fds after the c/r.

Can you say if the c/r avoids that kind of race condition?

Thanks,
-- Jamie