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 f01b936..642e0e5 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 c6f1392..874abf8 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 2fd1901..7d0b0bc 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)
 		return -ENOMEM;
-	down_write(&tomoyo_alias_list_lock);
+	mutex_lock(&tomoyo_policy_lock);
 	list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
 		if (ptr->original_name != saved_original_name ||
 		    ptr->aliased_name != saved_aliased_name)
@@ -675,7 +671,7 @@ static int tomoyo_update_alias_entry(const char *original_name,
 	list_add_tail_rcu(&new_entry->list, &tomoyo_alias_list);
 	error = 0;
  out:
-	up_write(&tomoyo_alias_list_lock);
+	mutex_unlock(&tomoyo_policy_lock);
 	return error;
 }
 
@@ -745,7 +741,7 @@ struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
 	struct tomoyo_domain_info *domain = NULL;
 	const struct tomoyo_path_info *saved_domainname;
 
-	down_write(&tomoyo_domain_list_lock);
+	mutex_lock(&tomoyo_policy_lock);
 	domain = tomoyo_find_domain(domainname);
 	if (domain)
 		goto out;
@@ -792,7 +788,7 @@ struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
 		list_add_tail_rcu(&domain->list, &tomoyo_domain_list);
 	}
  out:
-	up_write(&tomoyo_domain_list_lock);
+	mutex_unlock(&tomoyo_policy_lock);
 	return domain;
 }
 
diff --git a/security/tomoyo/file.c b/security/tomoyo/file.c
index 3c47286..5d1689d 100644
--- a/security/tomoyo/file.c
+++ b/security/tomoyo/file.c
@@ -167,9 +167,6 @@ static struct tomoyo_path_info *tomoyo_get_path(struct path *path)
 	return NULL;
 }
 
-/* Lock for domain->acl_info_list. */
-DECLARE_RWSEM(tomoyo_domain_acl_info_list_lock);
-
 static int tomoyo_update_double_path_acl(const u8 type, const char *filename1,
 					 const char *filename2,
 					 struct tomoyo_domain_info *
@@ -204,7 +201,6 @@ static int tomoyo_update_single_path_acl(const u8 type, const char *filename,
  * belongs to.
  */
 static LIST_HEAD(tomoyo_globally_readable_list);
-static DECLARE_RWSEM(tomoyo_globally_readable_list_lock);
 
 /**
  * tomoyo_update_globally_readable_entry - Update "struct tomoyo_globally_readable_file_entry" list.
@@ -229,7 +225,7 @@ static int tomoyo_update_globally_readable_entry(const char *filename,
 	saved_filename = tomoyo_save_name(filename);
 	if (!saved_filename)
 		return -ENOMEM;
-	down_write(&tomoyo_globally_readable_list_lock);
+	mutex_lock(&tomoyo_policy_lock);
 	list_for_each_entry_rcu(ptr, &tomoyo_globally_readable_list, list) {
 		if (ptr->filename != saved_filename)
 			continue;
@@ -248,7 +244,7 @@ static int tomoyo_update_globally_readable_entry(const char *filename,
 	list_add_tail_rcu(&new_entry->list, &tomoyo_globally_readable_list);
 	error = 0;
  out:
-	up_write(&tomoyo_globally_readable_list_lock);
+	mutex_unlock(&tomoyo_policy_lock);
 	return error;
 }
 
@@ -352,7 +348,6 @@ bool tomoyo_read_globally_readable_policy(struct tomoyo_io_buffer *head)
  * current process from accessing other process's information.
  */
 static LIST_HEAD(tomoyo_pattern_list);
-static DECLARE_RWSEM(tomoyo_pattern_list_lock);
 
 /**
  * tomoyo_update_file_pattern_entry - Update "struct tomoyo_pattern_entry" list.
@@ -377,7 +372,7 @@ static int tomoyo_update_file_pattern_entry(const char *pattern,
 	saved_pattern = tomoyo_save_name(pattern);
 	if (!saved_pattern)
 		return -ENOMEM;
-	down_write(&tomoyo_pattern_list_lock);
+	mutex_lock(&tomoyo_policy_lock);
 	list_for_each_entry_rcu(ptr, &tomoyo_pattern_list, list) {
 		if (saved_pattern != ptr->pattern)
 			continue;
@@ -396,7 +391,7 @@ static int tomoyo_update_file_pattern_entry(const char *pattern,
 	list_add_tail_rcu(&new_entry->list, &tomoyo_pattern_list);
 	error = 0;
  out:
-	up_write(&tomoyo_pattern_list_lock);
+	mutex_unlock(&tomoyo_policy_lock);
 	return error;
 }
 
@@ -505,7 +500,6 @@ bool tomoyo_read_file_pattern(struct tomoyo_io_buffer *head)
  * need to worry whether the file is already unlink()ed or not.
  */
 static LIST_HEAD(tomoyo_no_rewrite_list);
-static DECLARE_RWSEM(tomoyo_no_rewrite_list_lock);
 
 /**
  * tomoyo_update_no_rewrite_entry - Update "struct tomoyo_no_rewrite_entry" list.
@@ -529,7 +523,7 @@ static int tomoyo_update_no_rewrite_entry(const char *pattern,
 	saved_pattern = tomoyo_save_name(pattern);
 	if (!saved_pattern)
 		return -ENOMEM;
-	down_write(&tomoyo_no_rewrite_list_lock);
+	mutex_lock(&tomoyo_policy_lock);
 	list_for_each_entry_rcu(ptr, &tomoyo_no_rewrite_list, list) {
 		if (ptr->pattern != saved_pattern)
 			continue;
@@ -548,7 +542,7 @@ static int tomoyo_update_no_rewrite_entry(const char *pattern,
 	list_add_tail_rcu(&new_entry->list, &tomoyo_no_rewrite_list);
 	error = 0;
  out:
-	up_write(&tomoyo_no_rewrite_list_lock);
+	mutex_unlock(&tomoyo_policy_lock);
 	return error;
 }
 
@@ -881,7 +875,7 @@ static int tomoyo_update_single_path_acl(const u8 type, const char *filename,
 	saved_filename = tomoyo_save_name(filename);
 	if (!saved_filename)
 		return -ENOMEM;
-	down_write(&tomoyo_domain_acl_info_list_lock);
+	mutex_lock(&tomoyo_policy_lock);
 	if (is_delete)
 		goto delete;
 	list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
@@ -943,7 +937,7 @@ static int tomoyo_update_single_path_acl(const u8 type, const char *filename,
 		break;
 	}
  out:
-	up_write(&tomoyo_domain_acl_info_list_lock);
+	mutex_unlock(&tomoyo_policy_lock);
 	return error;
 }
 
@@ -981,7 +975,7 @@ static int tomoyo_update_double_path_acl(const u8 type, const char *filename1,
 	saved_filename2 = tomoyo_save_name(filename2);
 	if (!saved_filename1 || !saved_filename2)
 		return -ENOMEM;
-	down_write(&tomoyo_domain_acl_info_list_lock);
+	mutex_lock(&tomoyo_policy_lock);
 	if (is_delete)
 		goto delete;
 	list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
@@ -1027,7 +1021,7 @@ static int tomoyo_update_double_path_acl(const u8 type, const char *filename1,
 		break;
 	}
  out:
-	up_write(&tomoyo_domain_acl_info_list_lock);
+	mutex_unlock(&tomoyo_policy_lock);
 	return error;
 }