Subject: Re: [PATCH V2] Add flow control to the portmapper

From: Leon Romanovsky <[email-masked]>
Date: Thu, 21 Jul 2016 20:29:42 +0300

On Wed, Jul 20, 2016 at 09:47:50PM -0500, Shiraz Saleem wrote:
> On Tue, Jul 19, 2016 at 08:32:53PM +0300, Leon Romanovsky wrote:
> > On Tue, Jul 19, 2016 at 09:50:24AM -0500, Shiraz Saleem wrote:
> > > On Tue, Jul 19, 2016 at 08:40:06AM +0300, Leon Romanovsky wrote:
> > > > 
> > > > You are the one user of this new inline function.
> > > > Why don't you directly call to netlink_unicast() in your ibnl_unicast()
> > > > without messing with widely visible header file?
> > > 
> > > Since there is a non-blocking version of nlmsg_unicast(), the idea is 
> > > to make a blocking version available to others as well as maintain 
> > > consistency of existing code.
> > > 
> > 
> > In such way, please provide patch series which will convert all other
> > users to this new call.
> > 
> > ➜  linux-rdma git:(master) grep -rI netlink_unicast * | grep -I 0
> > kernel/audit.c: err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
> > kernel/audit.c:         netlink_unicast(aunet->nlsk, skb, dest->portid, 0);
> > kernel/audit.c: netlink_unicast(aunet->nlsk , reply->skb, reply->portid, 0);
> > kernel/audit.c: return netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
> > samples/connector/cn_test.c:    netlink_unicast(nls, skb, 0, 0);
> 
> These usages of netlink_unicast() with blocking are not the same as the new
> nlmsg_unicast_block() function. 

Really?
Did you look in the code?
Let's take first function from that grep output

414         err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
415         if (err < 0) {
			... do something ...
437         } else
			... do something else ...

which fits nicely with your proposal.

+static inline int nlmsg_unicast_block(struct sock *sk, struct sk_buff *skb, u32 portid)
+{
+       int err;
+
+       err = netlink_unicast(sk, skb, portid, 0);
+       if (err > 0)
+               err = 0;
+
+       return err;
+}

> You can't drop in nlmsg_unicast_block() in 
> place of netlink_unicast() in these places. I'm not going to introduce code 
> which modifies old behavior.

Again, you aren't changing any behaviour.
Anyway we are not adding general function to common include file just
because one caller wants it.