tomoyo: Fix null pointer check

Since tomoyo_memory_ok() will check for null pointer returned by
kzalloc() in tomoyo_assign_profile(), tomoyo_assign_namespace(),
tomoyo_get_name() and tomoyo_commit_ok(), then emit OOM warnings
if needed. And this is the expected behavior as informed by
Tetsuo Handa.

Let's add __GFP_NOWARN to kzalloc() in those related functions.
Besides, to achieve this goal, remove the null check for entry
right after kzalloc() in tomoyo_assign_namespace().

Reported-by: Hulk Robot <[e-mail]>
Suggested-by: Tetsuo Handa <[e-mail]>
Signed-off-by: Zheng Zengkai <[e-mail]>
Signed-off-by: Tetsuo Handa <[e-mail]>

security/tomoyo/common.c

···
 	ptr = ns->profile_ptr[profile];
 	if (ptr)
 		return ptr;
-	entry = kzalloc(sizeof(*entry), GFP_NOFS);
+	entry = kzalloc(sizeof(*entry), GFP_NOFS | __GFP_NOWARN);
 	if (mutex_lock_interruptible(&tomoyo_policy_lock))
 		goto out;
 	ptr = ns->profile_ptr[profile];

security/tomoyo/domain.c

···
 		return ptr;
 	if (len >= TOMOYO_EXEC_TMPSIZE - 10 || !tomoyo_domain_def(domainname))
 		return NULL;
-	entry = kzalloc(sizeof(*entry) + len + 1, GFP_NOFS);
-	if (!entry)
-		return NULL;
+	entry = kzalloc(sizeof(*entry) + len + 1, GFP_NOFS | __GFP_NOWARN);
 	if (mutex_lock_interruptible(&tomoyo_policy_lock))
 		goto out;
 	ptr = tomoyo_find_namespace(domainname, len);

security/tomoyo/memory.c

···
  */
 void *tomoyo_commit_ok(void *data, const unsigned int size)
 {
-	void *ptr = kzalloc(size, GFP_NOFS);
+	void *ptr = kzalloc(size, GFP_NOFS | __GFP_NOWARN);
 
 	if (tomoyo_memory_ok(ptr)) {
 		memmove(ptr, data, size);
···
 		atomic_inc(&ptr->head.users);
 		goto out;
 	}
-	ptr = kzalloc(sizeof(*ptr) + len, GFP_NOFS);
+	ptr = kzalloc(sizeof(*ptr) + len, GFP_NOFS | __GFP_NOWARN);
 	if (tomoyo_memory_ok(ptr)) {
 		ptr->entry.name = ((char *) ptr) + sizeof(*ptr);
 		memmove((char *) ptr->entry.name, name, len);