From 2c6ffe34a171c79ad25bbe0ef1f4e641a20bf3a3 Mon Sep 17 00:00:00 2001
From: Mathieu Maret <mathieu.maret@gmail.com>
Date: Tue, 26 Oct 2021 22:08:36 +0200
Subject: [PATCH] Allow to unref unrefered page

---
 core/mem.c | 8 +++++---
 core/mem.h | 2 ++
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/core/mem.c b/core/mem.c
index d74b31f..de471b0 100644
--- a/core/mem.c
+++ b/core/mem.c
@@ -1,8 +1,9 @@
-#include "mem.h"
 #include "assert.h"
+#include "errno.h"
 #include "kernel.h"
 #include "klibc.h"
 #include "list.h"
+#include "mem.h"
 #include "types.h"
 
 static struct phyMemDesc *pageDesc = (struct phyMemDesc *)&__ld_kernel_end;
@@ -139,9 +140,10 @@ int unrefPhyPage(paddr_t addr)
 {
     struct phyMemDesc *mem = addr2memDesc(addr);
     if (!mem) {
-        return -1;
+        return -EINVAL;
     }
-    assert(mem->ref > 0);
+    if(mem->ref <= 0)
+        return -EINVAL;
     mem->ref--;
     if (mem->ref == 0) {
         allocatedPage--;
diff --git a/core/mem.h b/core/mem.h
index b16fdb6..278c930 100644
--- a/core/mem.h
+++ b/core/mem.h
@@ -7,6 +7,8 @@
 
 #define PAGE_SHIFT 12U
 #define PAGE_SIZE (1U << PAGE_SHIFT)
+#define PAGE_MASK  (PAGE_SIZE - 1)
+
 
 // Defined in linker.ld script
 extern uint32_t __ld_kernel_begin;