diff --git a/.vscode/settings.json b/.vscode/settings.json
index c587b0a..f0a0daf 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,5 +1,9 @@
 {
     "files.associations": {
-        "ratio": "c"
+        "ratio": "c",
+        "__functional_03": "c",
+        "functional": "c",
+        "locale": "c",
+        "*.inc": "c"
     }
 }
\ No newline at end of file
diff --git a/pintos-env/pintos/threads/thread.c b/pintos-env/pintos/threads/thread.c
index 7305c7b..fa0a822 100644
--- a/pintos-env/pintos/threads/thread.c
+++ b/pintos-env/pintos/threads/thread.c
@@ -440,7 +440,7 @@ thread_exit (void)
   printf("%s: exit(%d)\n", t->name, t->exit_status);
   list_remove (&t->allelem);
   sema_up(&t->waiting_sem);
-  sema_down(&t->parent->parent_sem);
+  sema_down(&t->parent_sem);
   t->status = THREAD_DYING;
   list_remove(&t->child_elem);
   schedule ();
diff --git a/pintos-env/pintos/userprog/process.c b/pintos-env/pintos/userprog/process.c
index e90620e..0f73872 100755
--- a/pintos-env/pintos/userprog/process.c
+++ b/pintos-env/pintos/userprog/process.c
@@ -18,6 +18,8 @@
 #include "threads/thread.h"
 #include "threads/vaddr.h"
 #include "lib/kernel/list.h"
+#include "userprog/syscall.h"
+#include "threads/synch.h"
 
 static struct arg {
   struct list_elem elem;
@@ -59,11 +61,13 @@ process_execute (const char *file_name)
   }
   strlcpy(program_name, file_name, i+1);
 
+  lock_acquire(&filesys_lock);
   struct file* f = filesys_open (program_name);
   if (f == NULL) {
     return TID_ERROR;
   }
   file_close(f);
+  lock_release(&filesys_lock);
 
   /* Create a new thread to execute FILE_NAME. */
   tid = thread_create (program_name, PRI_DEFAULT, start_process, fn_copy);
@@ -104,6 +108,7 @@ start_process (void *file_name_)
   if_.gs = if_.fs = if_.es = if_.ds = if_.ss = SEL_UDSEG;
   if_.cs = SEL_UCSEG;
   if_.eflags = FLAG_IF | FLAG_MBS;
+  //printf("Loading %s\n", program_name);
   success = load (program_name, &if_.eip, &if_.esp);
 
   list_reverse(&arg_list);
@@ -200,7 +205,7 @@ process_wait (tid_t child_tid)
   int status = child->exit_status;
   //printf("Wait exit: %s %d\n",child->name, status);
   child->waited_on_before = 1;
-  sema_up(&(thread_current()->parent_sem));
+  sema_up(&(child->parent_sem));
   return status;
 }
 
@@ -334,6 +339,7 @@ load (const char *file_name, void (**eip) (void), void **esp)
     goto done;
   process_activate ();
 
+  lock_acquire(&filesys_lock);
   /* Open executable file. */
   file = filesys_open (file_name);
   if (file == NULL) 
@@ -426,6 +432,7 @@ load (const char *file_name, void (**eip) (void), void **esp)
  done:
   /* We arrive here whether the load is successful or not. */
   file_close (file);
+  lock_release(&filesys_lock);
   return success;
 }
 
diff --git a/pintos-env/pintos/userprog/syscall.c b/pintos-env/pintos/userprog/syscall.c
index 665bf8b..2d12b76 100755
--- a/pintos-env/pintos/userprog/syscall.c
+++ b/pintos-env/pintos/userprog/syscall.c
@@ -40,7 +40,7 @@ struct fd_item {
 
 int next_fd = 3;
 struct hash fd_table;
-struct semaphore filesys_lock;
+struct lock filesys_lock;
 
 static unsigned item_hash (const struct hash_elem* e, void* aux) {
   struct fd_item* i = hash_entry(e, struct fd_item, elem);
@@ -72,7 +72,7 @@ syscall_init (void)
   syscall_vec[SYS_READ] = (handler)sys_read;
   syscall_vec[SYS_WRITE] = (handler)sys_write;
   hash_init(&fd_table, item_hash, item_compare, NULL);
-  sema_init(&filesys_lock, 1);
+  lock_init(&filesys_lock);
 }
 
 static bool check_ptr(const void* ptr) {
@@ -90,17 +90,17 @@ void sys_halt(void) {
 
 bool sys_create(const char* filename, unsigned initial_size) {
   if (check_ptr(filename)) return 0;
-  sema_down (&filesys_lock);
+  lock_acquire (&filesys_lock);
   bool return_code = filesys_create(filename, initial_size);
-  sema_up (&filesys_lock);
+  lock_release (&filesys_lock);
   return return_code;
 }
 
 bool sys_remove(const char* filename) {
   if (check_ptr(filename)) return 0;
-  sema_down (&filesys_lock);
+  lock_acquire (&filesys_lock);
   bool return_code = filesys_remove(filename);
-  sema_up (&filesys_lock);
+  lock_release (&filesys_lock);
   return return_code;
 }
 
@@ -112,40 +112,42 @@ int sys_open(const char* file) {
     return -1;
   }
 
-  sema_down (&filesys_lock);
+  lock_acquire (&filesys_lock);
   file_opened = filesys_open(file);
+  //printf("File opened: %x\n", file_opened);
   if (!file_opened) {
     free(fd);
-    sema_up (&filesys_lock);
+    lock_release (&filesys_lock);
     return -1;
   }
 
-  fd->file = file_opened; //file save
+  fd->file = file_opened; 
   fd->fd = next_fd++;
+  //printf("Hash put: %x %d\n", file_opened, fd->fd);
   hash_insert(&fd_table, &fd->elem);
 
-  sema_up (&filesys_lock);
+  lock_release (&filesys_lock);
   return fd->fd;
 }
 
 int sys_filesize(int fd) {
-  sema_down (&filesys_lock);
+  lock_acquire (&filesys_lock);
   struct fd_item i;
   i.fd = fd;
   struct fd_item* file_d = hash_entry(hash_find(&fd_table, &i.elem), struct fd_item, elem);
 
   if(file_d == NULL) {
-    sema_up (&filesys_lock);
+    lock_release (&filesys_lock);
     return -1;
   }
 
   int ret = file_length(file_d->file);
-  sema_up (&filesys_lock);
+  lock_release (&filesys_lock);
   return ret;
 }
 
 void sys_seek(int fd, unsigned position) {
-  sema_down (&filesys_lock);
+  lock_acquire (&filesys_lock);
   struct fd_item i;
   i.fd = fd;
   struct fd_item* file_d = hash_entry(hash_find(&fd_table, &i.elem), struct fd_item, elem);
@@ -156,11 +158,11 @@ void sys_seek(int fd, unsigned position) {
   else
     return; 
 
-  sema_up (&filesys_lock);
+  lock_release (&filesys_lock);
 }
 
 unsigned sys_tell(int fd) {
-  sema_down (&filesys_lock);
+  lock_acquire (&filesys_lock);
   struct fd_item i;
   i.fd = fd;
   struct fd_item* file_d = hash_entry(hash_find(&fd_table, &i.elem), struct fd_item, elem);
@@ -172,29 +174,30 @@ unsigned sys_tell(int fd) {
   else
     ret = -1; 
 
-  sema_up (&filesys_lock);
+  lock_release (&filesys_lock);
   return ret;
 }
 
 void sys_close(int fd) {
-  sema_down (&filesys_lock);
+  lock_acquire (&filesys_lock);
   struct fd_item i;
   i.fd = fd;
   struct hash_elem* h = hash_find(&fd_table, &i.elem);
   if (h == NULL) sys_exit(-1);
   struct fd_item* file_d = hash_entry(h, struct fd_item, elem);
-
+  //printf("File close id: %x\n", file_d);
   if(file_d && file_d->file) {
+    //printf("File closed: %x\n", file_d->file);
     file_close(file_d->file);
     hash_delete(&fd_table, &(file_d->elem));
     free(file_d);
   }
-  sema_up (&filesys_lock);
+  lock_release (&filesys_lock);
 }
 
 int sys_read(int fd, void *buffer, unsigned size) {
   if (check_ptr(buffer)||check_ptr(buffer+size)) return -1;
-  sema_down (&filesys_lock);
+  lock_acquire (&filesys_lock);
   int ret;
 
   if(fd == 0) { 
@@ -206,14 +209,12 @@ int sys_read(int fd, void *buffer, unsigned size) {
     if (h == NULL) sys_exit(-1);
     struct fd_item* file_d = hash_entry(h, struct fd_item, elem);
 
-    if(file_d && file_d->file) {
+    if (file_d && file_d->file) {
       ret = file_read(file_d->file, buffer, size);
-    }
-    else // no such file or can't open
-      ret = -1;
+    } else ret = -1;
   }
 
-  sema_up (&filesys_lock);
+  lock_release (&filesys_lock);
   return ret;
 }
 
@@ -224,11 +225,11 @@ int sys_write(int fd, const void *buffer, unsigned size) {
   }
   int ret;
 
-  if(fd == 1) { // write to stdout
+  if(fd == 1) {
     putbuf(buffer, size);
     ret = size;
   } else {
-    sema_down (&filesys_lock);
+    lock_acquire (&filesys_lock);
     struct fd_item i;
     i.fd = fd;
     struct hash_elem* h = hash_find(&fd_table, &i.elem);
@@ -238,9 +239,8 @@ int sys_write(int fd, const void *buffer, unsigned size) {
     if(file_d && file_d->file) {
       ret = file_write(file_d->file, buffer, size);
     }
-    else // no such file or can't open
-      ret = -1;
-    sema_up (&filesys_lock);
+    else ret = -1;
+    lock_release (&filesys_lock);
   }
 
   return ret;
@@ -277,9 +277,7 @@ sys_exit (int status)
 int
 sys_wait (tid_t tid)
 {
-  //printf("system call wait\n");
   int status = process_wait(tid);
-  //printf("wait has returned status(%d)\n", status);
   return status;
 }
 
@@ -289,6 +287,5 @@ sys_exec (const char* file_name) {
       pagedir_get_page(thread_current()->pagedir, file_name) == NULL) {
     return -1;
   }
-
   return process_execute(file_name);
 }
\ No newline at end of file
diff --git a/pintos-env/pintos/userprog/syscall.h b/pintos-env/pintos/userprog/syscall.h
index 9059096..35a20aa 100755
--- a/pintos-env/pintos/userprog/syscall.h
+++ b/pintos-env/pintos/userprog/syscall.h
@@ -3,4 +3,6 @@
 
 void syscall_init (void);
 
+struct lock filesys_lock;
+
 #endif /* userprog/syscall.h */