Re: [patch -mm] update mq_notify to use a struct pid

Eric W. Biederman wrote:

Cedric you mentioned a couple of other patches that are in flight.
In the future could you please Cc: the containers list so independent
efforts are less likely to duplicate work, and we are more likely
to review each others patches instead?

yes sure, i was relying on the openvz wiki to avoid duplicated efforts on
this topic but i guess email is just the one and only tool for this kind of
development :)

[ ... ]

Converting that is going to need some sysctl work, so I have been
ignoring it temporarily.

Filling in a struct pid through sysctl is extremely ugly at the
moment, plus cad_pid needs some locking.
Which distros use /proc/sys/kernel/cad_pid and why ? I can image the need
but i didn't find much on the topic.

I'm not at all certain, and I'm not even certain I care. The concept
is there in the code so it needs to be dealt with.

OK. It would be nice to make sure this is still in use before trying to
deal with /proc/sys/kernel/cad_pid.

Although if I we extend the cad_pid concept it may make a difference.

what do you mean by extending cad_pid ? kill_init() ?

[ ... ]

is that about updating the siginfos in collect_signal() to hold the right
pid value depending on the pid namespace they are being received ?

Yes in send_signal, and in collect signal. To make it work easily I needed
to add a struct pid to struct sigqueue. So in send_signal I generate
the struct pid from the pid_t value and in collect signal I regenerate
the numeric value.

OK. That's what i imagined also but we need a bit more of the pid namespace
to regenerate the numerical value. So, how will you convert this 'struct
pid*' in a pid value using the current pid namespace ?

thinking aloud :

* if the pid namespace of the sending struct pid and current match,
use nr.
* if they don't,
if the sending pid namespace is the ancestor of the current pid
namespace
use 0
else
it's a bug.

struct pid* needs a pid namespace attribute and pid namespace needs to know
its parent.

C.
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