>
> 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.
>
The key is to ensure that places calling a blocking service are never called in
a non-blocking context. Leon, do you know if the new sites are always safe to
block?
In general, I think blocking due to sockbuf flow control vs dropping or
retrying is a good thing for all the users in the rdam core, assuming they are
safe to block.
> +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.
Potential block/sleep is a change. But if we can conclude that these
additional sites are safe to block, then probably its ok to just go ahead and
use the blocking service everywhere.
