Re: [PATCH] Improve behaviour of Netlink Sockets

Pablo Neira [off-list ref] wrote:

you are right, I missed that, but I prefer the patches attached to this 
email. Now if netlink_broadcast_deliver function delivers correctly the 
packet, you decrease sock refcount and function returns 1. I think that 
I got confused because netlink_broadcast_deliver returns 0/-1.

Unfortunately it is still wrong.  You missed the exit path at the
very top.

And I think rather than adding all these new sock_put's, it's much
better to do what you mean and add a sock_hold on the new path that
you introduced.

quoted

Secondly, I'm dubious about the patch as a whole.  For instance, what
exactly is the wake_up_process() bit trying to do? Surely that process
would've been woken up multiple times already if its queue is full.

This is what I theorically expected, but in practice if you stress a 
netlink socket sending a big bunch of information in a short period of 
time from kernel space to user space, socket overruns easily. That's why 
I wake up the user process to make it process information stored in the 
queue. Socket doesn't overrun anymore with my patch.

Yes but your patch does a lot more than that wake_up_process.  Have you
reverted just the wake_up_process and seen a difference?

quoted

And what is it going to do with thread groups?

currently broadcast sockets can still overrun. I have a set of patches 
that I'll submit as soon as I test them and I finish my boring exams.

That's not what I meant.  If you have a thread group where everybody's
got the same pid, your code will probably wake up the wrong thread.

Besides, for any netlink socket but the first for a process, they'll
all have negative pid's which have nothing to do with the real pid.
So I really think that the wake_up_process hunk is bogus.

BTW I apologise for the few bounces that you got from my mail server.
It should be fixed now.  If you're still getting bounces, please let
me know via the list.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} [off-list ref]
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