[PATCH] wrong return codes in ipc shm

We always returned success even when we had no ->vm_ops

ipc/shm.c

@@ -674,16 +674,19 @@ asmlinkage long sys_shmdt (char *shmaddr)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *shmd, *shmdnext;
+	int retval = -EINVAL;
 
 	down_write(&mm->mmap_sem);
 	for (shmd = mm->mmap; shmd; shmd = shmdnext) {
 		shmdnext = shmd->vm_next;
 		if (shmd->vm_ops == &shm_vm_ops
-		    && shmd->vm_start - (shmd->vm_pgoff << PAGE_SHIFT) == (ulong) shmaddr)
+		    && shmd->vm_start - (shmd->vm_pgoff << PAGE_SHIFT) == (ulong) shmaddr) {
 			do_munmap(mm, shmd->vm_start, shmd->vm_end - shmd->vm_start);
+			retval = 0;
+		}
 	}
 	up_write(&mm->mmap_sem);
-	return 0;
+	return retval;
 }
 
 #ifdef CONFIG_PROC_FS