TOMOYO: Replace rw_semaphore by mutex.

Since readers no longer use down_read(), writers no longer
need to use rw_semaphore. Replace individual rw_semaphore by
single mutex.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

4 files changed, 27 insertions, 36 deletions

diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index f01b9364db2d..642e0e565dfc 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -16,6 +16,9 @@
 #include "common.h"
 #include "tomoyo.h"
 
+/* Lock for protecting policy. */
+DEFINE_MUTEX(tomoyo_policy_lock);
+
 /* Has loading policy done? */
 bool tomoyo_policy_loaded;
 
@@ -1086,7 +1089,6 @@ struct tomoyo_policy_manager_entry {
  * # cat /sys/kernel/security/tomoyo/manager
  */
 static LIST_HEAD(tomoyo_policy_manager_list);
-static DECLARE_RWSEM(tomoyo_policy_manager_list_lock);
 
 /**
  * tomoyo_update_manager_entry - Add a manager entry.
@@ -1118,7 +1120,7 @@ static int tomoyo_update_manager_entry(const char *manager,
         saved_manager = tomoyo_save_name(manager);
         if (!saved_manager)
                 return -ENOMEM;
-        down_write(&tomoyo_policy_manager_list_lock);
+        mutex_lock(&tomoyo_policy_lock);
         list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
                 if (ptr->manager != saved_manager)
                         continue;
@@ -1138,7 +1140,7 @@ static int tomoyo_update_manager_entry(const char *manager,
         list_add_tail_rcu(&new_entry->list, &tomoyo_policy_manager_list);
         error = 0;
  out:
-        up_write(&tomoyo_policy_manager_list_lock);
+        mutex_unlock(&tomoyo_policy_lock);
         return error;
 }
 
@@ -1315,7 +1317,7 @@ static int tomoyo_delete_domain(char *domainname)
 
         name.name = domainname;
         tomoyo_fill_path_info(&name);
-        down_write(&tomoyo_domain_list_lock);
+        mutex_lock(&tomoyo_policy_lock);
         /* Is there an active domain? */
         list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
                 /* Never delete tomoyo_kernel_domain */
@@ -1327,7 +1329,7 @@ static int tomoyo_delete_domain(char *domainname)
                 domain->is_deleted = true;
                 break;
         }
-        up_write(&tomoyo_domain_list_lock);
+        mutex_unlock(&tomoyo_policy_lock);
         return 0;
 }
 
diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h
index c6f13925472a..874abf8df43e 100644
--- a/security/tomoyo/common.h
+++ b/security/tomoyo/common.h
@@ -431,10 +431,9 @@ static inline bool tomoyo_is_invalid(const unsigned char c)
 
 /* The list for "struct tomoyo_domain_info". */
 extern struct list_head tomoyo_domain_list;
-extern struct rw_semaphore tomoyo_domain_list_lock;
 
-/* Lock for domain->acl_info_list. */
-extern struct rw_semaphore tomoyo_domain_acl_info_list_lock;
+/* Lock for protecting policy. */
+extern struct mutex tomoyo_policy_lock;
 
 /* Has /sbin/init started? */
 extern bool tomoyo_policy_loaded;
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 2fd190168b7e..7d0b0bc48201 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -58,7 +58,6 @@ struct tomoyo_domain_info tomoyo_kernel_domain;
  * exceptions.
  */
 LIST_HEAD(tomoyo_domain_list);
-DECLARE_RWSEM(tomoyo_domain_list_lock);
 
 /*
  * tomoyo_domain_initializer_entry is a structure which is used for holding
@@ -206,7 +205,6 @@ const char *tomoyo_get_last_name(const struct tomoyo_domain_info *domain)
  * unless executed from "<kernel> /etc/rc.d/init.d/httpd" domain.
  */
 static LIST_HEAD(tomoyo_domain_initializer_list);
-static DECLARE_RWSEM(tomoyo_domain_initializer_list_lock);
 
 /**
  * tomoyo_update_domain_initializer_entry - Update "struct tomoyo_domain_initializer_entry" list.
@@ -247,7 +245,7 @@ static int tomoyo_update_domain_initializer_entry(const char *domainname,
         saved_program = tomoyo_save_name(program);
         if (!saved_program)
                 return -ENOMEM;
-        down_write(&tomoyo_domain_initializer_list_lock);
+        mutex_lock(&tomoyo_policy_lock);
         list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list, list) {
                 if (ptr->is_not != is_not ||
                     ptr->domainname != saved_domainname ||
@@ -271,7 +269,7 @@ static int tomoyo_update_domain_initializer_entry(const char *domainname,
         list_add_tail_rcu(&new_entry->list, &tomoyo_domain_initializer_list);
         error = 0;
  out:
-        up_write(&tomoyo_domain_initializer_list_lock);
+        mutex_unlock(&tomoyo_policy_lock);
         return error;
 }
 
@@ -423,7 +421,6 @@ static bool tomoyo_is_domain_initializer(const struct tomoyo_path_info *
  * explicitly specified by "initialize_domain".
  */
 static LIST_HEAD(tomoyo_domain_keeper_list);
-static DECLARE_RWSEM(tomoyo_domain_keeper_list_lock);
 
 /**
  * tomoyo_update_domain_keeper_entry - Update "struct tomoyo_domain_keeper_entry" list.
@@ -464,7 +461,7 @@ static int tomoyo_update_domain_keeper_entry(const char *domainname,
         saved_domainname = tomoyo_save_name(domainname);
         if (!saved_domainname)
                 return -ENOMEM;
-        down_write(&tomoyo_domain_keeper_list_lock);
+        mutex_lock(&tomoyo_policy_lock);
         list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
                 if (ptr->is_not != is_not ||
                     ptr->domainname != saved_domainname ||
@@ -488,7 +485,7 @@ static int tomoyo_update_domain_keeper_entry(const char *domainname,
         list_add_tail_rcu(&new_entry->list, &tomoyo_domain_keeper_list);
         error = 0;
  out:
-        up_write(&tomoyo_domain_keeper_list_lock);
+        mutex_unlock(&tomoyo_policy_lock);
         return error;
 }
 
@@ -624,7 +621,6 @@ static bool tomoyo_is_domain_keeper(const struct tomoyo_path_info *domainname,
  * execve() succeeds is calculated using /bin/cat rather than /bin/busybox .
  */
 static LIST_HEAD(tomoyo_alias_list);
-static DECLARE_RWSEM(tomoyo_alias_list_lock);
 
 /**
  * tomoyo_update_alias_entry - Update "struct tomoyo_alias_entry" list.
@@ -654,7 +650,7 @@ static int tomoyo_update_alias_entry(const char *original_name,
         saved_aliased_name = tomoyo_save_name(aliased_name);
         if (!saved_original_name || !saved_aliased_name)