On 3/9/23 3:49 AM, D. Wythe wrote:
--- /dev/null
+++ b/net/smc/bpf_smc_struct_ops.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kernel.h>
+#include <linux/bpf_verifier.h>
+#include <linux/btf_ids.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <net/sock.h>
+#include <net/smc.h>
+
+extern struct bpf_struct_ops smc_sock_negotiator_ops;
+
+DEFINE_RWLOCK(smc_sock_negotiator_ops_rwlock);
+struct smc_sock_negotiator_ops *negotiator;
Is it sure one global negotiator (policy) will work for all smc_sock? or each
sk should have its own negotiator and the negotiator is selected by setsockopt.
This is really a good question, we can really consider adding an independent
negotiator for each sock.
But just like the TCP congestion control , the global negotiator can be used for
sock without
special requirements.
It is different from TCP congestion control (CC). TCP CC has a global default
but each sk can select what tcp-cc to use and there can be multiple tcp-cc
registered under different names.
It sounds like smc using tcp_sock should be able to have different negotiator
also (eg. based on dst IP or some other tcp connection characteristic). The
tcp-cc registration, per-sock selection and the rcu_read_lock+refcnt are well
understood and there are other bpf infrastructure to support the per sock tcp-cc
selection (like bpf_setsockopt).
For the network stack, there is little reason other af_* should not follow at
the beginning considering the infrastructure has already been built. The one
single global negotiator and reader/writer lock in this patch reads like an
effort wanted to give it a try and see if it will be useful before implementing
the whole thing. It is better to keep it off the tree for now until it is more
ready.
