net/smc: disable SEID on non-s390 archs where virtual ISM may be used

The system EID (SEID) is an internal EID used by SMC-D to represent the
s390 physical machine that OS is executing on. On s390 architecture, it
predefined by fixed string and part of cpuid and is enabled regardless
of whether underlay device is virtual ISM or platform firmware ISM.

However on non-s390 architectures where SMC-D can be used with virtual
ISM devices, there is no similar information to identify physical
machines, especially in virtualization scenarios. So in such cases, SEID
is forcibly disabled and the user-defined UEID will be used to represent
the communicable space.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Reviewed-and-tested-by: Wenjia Zhang <wenjia@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
index b43be3cafdcc3385a0561b0bc9a2b5766fd70b56..9a13709bea1cb38129e4122e28232ab84e3a66ff 100644 (file)
--- a/net/smc/smc_clc.c
+++ b/net/smc/smc_clc.c
@@ -155,10 +155,12 @@ static int smc_clc_ueid_remove(char *ueid)
                        rc = 0;
                }
        }
+#if IS_ENABLED(CONFIG_S390)
        if (!rc && !smc_clc_eid_table.ueid_cnt) {
                smc_clc_eid_table.seid_enabled = 1;
                rc = -EAGAIN;   /* indicate success and enabling of seid */
        }
+#endif
        write_unlock(&smc_clc_eid_table.lock);
        return rc;
 }
@@ -273,22 +275,30 @@ err:
 
 int smc_nl_enable_seid(struct sk_buff *skb, struct genl_info *info)
 {
+#if IS_ENABLED(CONFIG_S390)
        write_lock(&smc_clc_eid_table.lock);
        smc_clc_eid_table.seid_enabled = 1;
        write_unlock(&smc_clc_eid_table.lock);
        return 0;
+#else
+       return -EOPNOTSUPP;
+#endif
 }
 
 int smc_nl_disable_seid(struct sk_buff *skb, struct genl_info *info)
 {
        int rc = 0;
 
+#if IS_ENABLED(CONFIG_S390)
        write_lock(&smc_clc_eid_table.lock);
        if (!smc_clc_eid_table.ueid_cnt)
                rc = -ENOENT;
        else
                smc_clc_eid_table.seid_enabled = 0;
        write_unlock(&smc_clc_eid_table.lock);
+#else
+       rc = -EOPNOTSUPP;
+#endif
        return rc;
 }
 
@@ -1328,7 +1338,11 @@ void __init smc_clc_init(void)
        INIT_LIST_HEAD(&smc_clc_eid_table.list);
        rwlock_init(&smc_clc_eid_table.lock);
        smc_clc_eid_table.ueid_cnt = 0;
+#if IS_ENABLED(CONFIG_S390)
        smc_clc_eid_table.seid_enabled = 1;
+#else
+       smc_clc_eid_table.seid_enabled = 0;
+#endif
 }
 
 void smc_clc_exit(void)