From bae37aa507bd5a74707ca37d5e0ee6d347dfe1ea Mon Sep 17 00:00:00 2001
From: Garen Tyler <garentyler@garen.dev>
Date: Fri, 3 Nov 2023 18:48:55 -0600
Subject: [PATCH] move nextpid into atomic i32 in rust

---
 kernel/proc.c                      |  6 +-----
 kernel/rustkernel/src/proc/proc.rs | 12 ++++++------
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/kernel/proc.c b/kernel/proc.c
index d4003eb..b1d1a4b 100644
--- a/kernel/proc.c
+++ b/kernel/proc.c
@@ -10,9 +10,6 @@ struct proc proc[NPROC];
 
 struct proc *initproc;
 
-int nextpid = 1;
-struct spinlock pid_lock;
-
 extern void forkret(void);
 void freeproc(struct proc *p);
 
@@ -46,8 +43,7 @@ void
 procinit(void)
 {
   struct proc *p;
-  
-  initlock(&pid_lock, "nextpid");
+
   initlock(&wait_lock, "wait_lock");
   for(p = proc; p < &proc[NPROC]; p++) {
       initlock(&p->lock, "proc");
diff --git a/kernel/rustkernel/src/proc/proc.rs b/kernel/rustkernel/src/proc/proc.rs
index 927ae19..b9a1f68 100644
--- a/kernel/rustkernel/src/proc/proc.rs
+++ b/kernel/rustkernel/src/proc/proc.rs
@@ -10,6 +10,7 @@ use crate::{
 use core::{
     ffi::{c_char, c_void},
     ptr::{addr_of_mut, null_mut},
+    sync::atomic::{AtomicI32, Ordering},
 };
 
 extern "C" {
@@ -45,6 +46,8 @@ extern "C" {
     pub fn swtch(a: *mut Context, b: *mut Context);
 }
 
+pub static NEXT_PID: AtomicI32 = AtomicI32::new(1);
+
 #[repr(C)]
 #[derive(PartialEq, Default)]
 pub enum ProcState {
@@ -164,7 +167,7 @@ impl Proc {
 
 /// Return the current struct proc *, or zero if none.
 #[no_mangle]
-pub unsafe extern "C" fn myproc() -> *mut Proc {
+pub extern "C" fn myproc() -> *mut Proc {
     if let Some(p) = Proc::current() {
         p as *mut Proc
     } else {
@@ -173,11 +176,8 @@ pub unsafe extern "C" fn myproc() -> *mut Proc {
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn allocpid() -> i32 {
-    let _guard = pid_lock.lock();
-    let pid = nextpid;
-    nextpid += 1;
-    pid
+pub extern "C" fn allocpid() -> i32 {
+    NEXT_PID.fetch_add(1, Ordering::SeqCst)
 }
 
 /// Free a proc structure and the data hanging from it, including user pages.