[NetLabel]: correct usage of RCU locking

This fixes some awkward, and perhaps even problematic, RCU lock usage in the
NetLabel code as well as some other related trivial cleanups found when
looking through the RCU locking.  Most of the changes involve removing the
redundant RCU read locks wrapping spinlocks in the case of a RCU writer.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 29 deletions

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 805a78e6ed55..f18e88bc86ec 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -504,22 +504,16 @@ int cipso_v4_doi_add(struct cipso_v4_doi *doi_def)
         INIT_RCU_HEAD(&doi_def->rcu);
         INIT_LIST_HEAD(&doi_def->dom_list);
 
-        rcu_read_lock();
-        if (cipso_v4_doi_search(doi_def->doi) != NULL)
-                goto doi_add_failure_rlock;
         spin_lock(&cipso_v4_doi_list_lock);
         if (cipso_v4_doi_search(doi_def->doi) != NULL)
-                goto doi_add_failure_slock;
+                goto doi_add_failure;
         list_add_tail_rcu(&doi_def->list, &cipso_v4_doi_list);
         spin_unlock(&cipso_v4_doi_list_lock);
-        rcu_read_unlock();
 
         return 0;
 
-doi_add_failure_slock:
+doi_add_failure:
         spin_unlock(&cipso_v4_doi_list_lock);
-doi_add_failure_rlock:
-        rcu_read_unlock();
         return -EEXIST;
 }
 
@@ -543,29 +537,23 @@ int cipso_v4_doi_remove(u32 doi,
         struct cipso_v4_doi *doi_def;
         struct cipso_v4_domhsh_entry *dom_iter;
 
-        rcu_read_lock();
-        if (cipso_v4_doi_search(doi) != NULL) {
-                spin_lock(&cipso_v4_doi_list_lock);
-                doi_def = cipso_v4_doi_search(doi);
-                if (doi_def == NULL) {
-                        spin_unlock(&cipso_v4_doi_list_lock);
-                        rcu_read_unlock();
-                        return -ENOENT;
-                }
+        spin_lock(&cipso_v4_doi_list_lock);
+        doi_def = cipso_v4_doi_search(doi);
+        if (doi_def != NULL) {
                 doi_def->valid = 0;
                 list_del_rcu(&doi_def->list);
                 spin_unlock(&cipso_v4_doi_list_lock);
+                rcu_read_lock();
                 list_for_each_entry_rcu(dom_iter, &doi_def->dom_list, list)
                         if (dom_iter->valid)
                                 netlbl_domhsh_remove(dom_iter->domain,
                                                      audit_info);
-                cipso_v4_cache_invalidate();
                 rcu_read_unlock();
-
+                cipso_v4_cache_invalidate();
                 call_rcu(&doi_def->rcu, callback);
                 return 0;
         }
-        rcu_read_unlock();
+        spin_unlock(&cipso_v4_doi_list_lock);
 
         return -ENOENT;
 }
@@ -653,22 +641,19 @@ int cipso_v4_doi_domhsh_add(struct cipso_v4_doi *doi_def, const char *domain)
         new_dom->valid = 1;
         INIT_RCU_HEAD(&new_dom->rcu);
 
-        rcu_read_lock();
         spin_lock(&cipso_v4_doi_list_lock);
-        list_for_each_entry_rcu(iter, &doi_def->dom_list, list)
+        list_for_each_entry(iter, &doi_def->dom_list, list)
                 if (iter->valid &&
                     ((domain != NULL && iter->domain != NULL &&
                       strcmp(iter->domain, domain) == 0) ||
                      (domain == NULL && iter->domain == NULL))) {
                         spin_unlock(&cipso_v4_doi_list_lock);
-                        rcu_read_unlock();
                         kfree(new_dom->domain);
                         kfree(new_dom);
                         return -EEXIST;
                 }
         list_add_tail_rcu(&new_dom->list, &doi_def->dom_list);
         spin_unlock(&cipso_v4_doi_list_lock);
-        rcu_read_unlock();
 
         return 0;
 }
@@ -689,9 +674,8 @@ int cipso_v4_doi_domhsh_remove(struct cipso_v4_doi *doi_def,
 {
         struct cipso_v4_domhsh_entry *iter;
 
-        rcu_read_lock();
         spin_lock(&cipso_v4_doi_list_lock);
-        list_for_each_entry_rcu(iter, &doi_def->dom_list, list)
+        list_for_each_entry(iter, &doi_def->dom_list, list)
                 if (iter->valid &&
                     ((domain != NULL && iter->domain != NULL &&
                       strcmp(iter->domain, domain) == 0) ||
@@ -699,13 +683,10 @@ int cipso_v4_doi_domhsh_remove(struct cipso_v4_doi *doi_def,
                         iter->valid = 0;
                         list_del_rcu(&iter->list);
                         spin_unlock(&cipso_v4_doi_list_lock);
-                        rcu_read_unlock();
                         call_rcu(&iter->rcu, cipso_v4_doi_domhsh_free);
-
                         return 0;
                 }
         spin_unlock(&cipso_v4_doi_list_lock);
-        rcu_read_unlock();
 
         return -ENOENT;
 }