[RFC PATCH v2 3/4] net: drop_monitor: use drop_reason_lookup()

[Johannes Berg]

From: Johannes Berg <johannes.b...@intel.com>

Now that we have drop_reason_lookup(), we can just use it for
drop_monitor as well, rather than exporting the list itself.

Signed-off-by: Johannes Berg <johannes.b...@intel.com>
---
 include/net/dropreason.h |  4 ----
 net/core/drop_monitor.c  | 18 +++---------------
 net/core/skbuff.c        |  6 +++---
 3 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index c157070b5303..0e2195ccf2cd 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -38,10 +38,6 @@ struct drop_reason_list {
        size_t n_reasons;
 };
 
-/* Note: due to dynamic registrations, access must be under RCU */
-extern const struct drop_reason_list __rcu *
-drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM];
-
 #ifdef CONFIG_TRACEPOINTS
 const char *drop_reason_lookup(unsigned long long value);
 void drop_reason_show(struct seq_file *m);
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index b0f221d658be..185c43e5b501 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -610,9 +610,8 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, 
struct sk_buff *skb,
                                     size_t payload_len)
 {
        struct net_dm_skb_cb *cb = NET_DM_SKB_CB(skb);
-       const struct drop_reason_list *list = NULL;
-       unsigned int subsys, subsys_reason;
        char buf[NET_DM_MAX_SYMBOL_LEN];
+       const char *reason_str;
        struct nlattr *attr;
        void *hdr;
        int rc;
@@ -630,19 +629,8 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, 
struct sk_buff *skb,
                goto nla_put_failure;
 
        rcu_read_lock();
-       subsys = u32_get_bits(cb->reason, SKB_DROP_REASON_SUBSYS_MASK);
-       if (subsys < SKB_DROP_REASON_SUBSYS_NUM)
-               list = rcu_dereference(drop_reasons_by_subsys[subsys]);
-       subsys_reason = cb->reason & ~SKB_DROP_REASON_SUBSYS_MASK;
-       if (!list ||
-           subsys_reason >= list->n_reasons ||
-           !list->reasons[subsys_reason] ||
-           strlen(list->reasons[subsys_reason]) > NET_DM_MAX_REASON_LEN) {
-               list = 
rcu_dereference(drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_CORE]);
-               subsys_reason = SKB_DROP_REASON_NOT_SPECIFIED;
-       }
-       if (nla_put_string(msg, NET_DM_ATTR_REASON,
-                          list->reasons[subsys_reason])) {
+       reason_str = drop_reason_lookup(cb->reason);
+       if (nla_put_string(msg, NET_DM_ATTR_REASON, reason_str)) {
                rcu_read_unlock();
                goto nla_put_failure;
        }
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 012b48da8810..a8065c40a270 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -141,13 +141,11 @@ static const struct drop_reason_list drop_reasons_core = {
        .n_reasons = ARRAY_SIZE(drop_reasons),
 };
 
-const struct drop_reason_list __rcu *
+static const struct drop_reason_list __rcu *
 drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM] = {
        [SKB_DROP_REASON_SUBSYS_CORE] = RCU_INITIALIZER(&drop_reasons_core),
 };
-EXPORT_SYMBOL(drop_reasons_by_subsys);
 
-#ifdef CONFIG_TRACEPOINTS
 const char *drop_reason_lookup(unsigned long long value)
 {
        unsigned long long subsys_id = value >> SKB_DROP_REASON_SUBSYS_SHIFT;
@@ -164,7 +162,9 @@ const char *drop_reason_lookup(unsigned long long value)
                return NULL;
        return subsys->reasons[reason];
 }
+EXPORT_SYMBOL(drop_reason_lookup);
 
+#ifdef CONFIG_TRACEPOINTS
 void drop_reason_show(struct seq_file *m)
 {
        u32 subsys_id;
-- 
2.44.0