net/smc: fix compile warning for smc_sysctl

kernel test robot reports multiple warning for smc_sysctl:

  In file included from net/smc/smc_sysctl.c:17:
>> net/smc/smc_sysctl.h:23:5: warning: no previous prototype \
	for function 'smc_sysctl_init' [-Wmissing-prototypes]
  int smc_sysctl_init(void)
       ^
and
  >> WARNING: modpost: vmlinux.o(.text+0x12ced2d): Section mismatch \
  in reference from the function smc_sysctl_exit() to the variable
  .init.data:smc_sysctl_ops
  The function smc_sysctl_exit() references
  the variable __initdata smc_sysctl_ops.
  This is often because smc_sysctl_exit lacks a __initdata
  annotation or the annotation of smc_sysctl_ops is wrong.

and
  net/smc/smc_sysctl.c: In function 'smc_sysctl_init_net':
  net/smc/smc_sysctl.c:47:17: error: 'struct netns_smc' has no member named 'smc_hdr'
     47 |         net->smc.smc_hdr = register_net_sysctl(net, "net/smc", table);

Since we don't need global sysctl initialization. To make things
clean and simple, remove the global pernet_operations and
smc_sysctl_{init|exit}. Call smc_sysctl_net_{init|exit} directly
from smc_net_{init|exit}.

Also initialized sysctl_autocorking_size if CONFIG_SYSCTL it not
set, this make sure SMC autocorking is enabled by default if
CONFIG_SYSCTL is not set.

Fixes: 462791bbfa ("net/smc: add sysctl interface for SMC")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dust Li <dust.li@linux.alibaba.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/Makefile

@@ -4,4 +4,5 @@ obj-$(CONFIG_SMC)	+= smc.o
 obj-$(CONFIG_SMC_DIAG)	+= smc_diag.o
 smc-y := af_smc.o smc_pnet.o smc_ib.o smc_clc.o smc_core.o smc_wr.o smc_llc.o
 smc-y += smc_cdc.o smc_tx.o smc_rx.o smc_close.o smc_ism.o smc_netlink.o smc_stats.o
-smc-y += smc_tracepoint.o smc_sysctl.o
+smc-y += smc_tracepoint.o
+smc-$(CONFIG_SYSCTL) += smc_sysctl.o

net/smc/af_smc.c

@@ -3179,11 +3179,17 @@ unsigned int smc_net_id;
 
 static __net_init int smc_net_init(struct net *net)
 {
+	int rc;
+
+	rc = smc_sysctl_net_init(net);
+	if (rc)
+		return rc;
 	return smc_pnet_net_init(net);
 }
 
 static void __net_exit smc_net_exit(struct net *net)
 {
+	smc_sysctl_net_exit(net);
 	smc_pnet_net_exit(net);
 }
 
@@ -3296,17 +3302,9 @@ static int __init smc_init(void)
 		goto out_ib;
 	}
 
-	rc = smc_sysctl_init();
-	if (rc) {
-		pr_err("%s: sysctl_init fails with %d\n", __func__, rc);
-		goto out_ulp;
-	}
-
 	static_branch_enable(&tcp_have_smc);
 	return 0;
 
-out_ulp:
-	tcp_unregister_ulp(&smc_ulp_ops);
 out_ib:
 	smc_ib_unregister_client();
 out_sock:
@@ -3336,7 +3334,6 @@ out_pernet_subsys:
 static void __exit smc_exit(void)
 {
 	static_branch_disable(&tcp_have_smc);
-	smc_sysctl_exit();
 	tcp_unregister_ulp(&smc_ulp_ops);
 	sock_unregister(PF_SMC);
 	smc_core_exit();

net/smc/smc_sysctl.c

@@ -28,7 +28,7 @@ static struct ctl_table smc_table[] = {
 	{  }
 };
 
-static __net_init int smc_sysctl_init_net(struct net *net)
+int __net_init smc_sysctl_net_init(struct net *net)
 {
 	struct ctl_table *table;
 
@@ -59,22 +59,7 @@ err_alloc:
 	return -ENOMEM;
 }
 
-static __net_exit void smc_sysctl_exit_net(struct net *net)
+void __net_exit smc_sysctl_net_exit(struct net *net)
 {
 	unregister_net_sysctl_table(net->smc.smc_hdr);
 }
-
-static struct pernet_operations smc_sysctl_ops __net_initdata = {
-	.init = smc_sysctl_init_net,
-	.exit = smc_sysctl_exit_net,
-};
-
-int __init smc_sysctl_init(void)
-{
-	return register_pernet_subsys(&smc_sysctl_ops);
-}
-
-void smc_sysctl_exit(void)
-{
-	unregister_pernet_subsys(&smc_sysctl_ops);
-}

net/smc/smc_sysctl.h

@@ -15,17 +15,18 @@
 
 #ifdef CONFIG_SYSCTL
 
-int smc_sysctl_init(void);
-void smc_sysctl_exit(void);
+int __net_init smc_sysctl_net_init(struct net *net);
+void __net_exit smc_sysctl_net_exit(struct net *net);
 
 #else
 
-int smc_sysctl_init(void)
+int __net_init smc_sysctl_net_init(struct net *net)
 {
+	net->smc.sysctl_autocorking_size = SMC_AUTOCORKING_DEFAULT_SIZE;
 	return 0;
 }
 
-void smc_sysctl_exit(void) { }
+void __net_exit smc_sysctl_net_exit(struct net *net) { }
 
 #endif /* CONFIG_SYSCTL */