From 280f07f387ddd94e7827f339f486b4d0c455055d Mon Sep 17 00:00:00 2001
From: nimelehin <nimelehin@gmail.com>
Date: Mon, 16 Nov 2020 19:01:40 +0300
Subject: [PATCH] Add pid_get_last_allocated()

---
 kernel/task.c | 19 +++++++++++++------
 kernel/task.h |  1 +
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/kernel/task.c b/kernel/task.c
index 334a7a74f5..65e3ed1d8e 100644
--- a/kernel/task.c
+++ b/kernel/task.c
@@ -9,6 +9,7 @@
 
 __thread struct task *current;
 
+static dword_t last_allocated_pid = 0;
 static struct pid pids[MAX_PID + 1] = {};
 lock_t pids_lock = LOCK_INITIALIZER;
 
@@ -40,15 +41,21 @@ struct task *pid_get_task(dword_t id) {
     return task;
 }
 
+struct pid *pid_get_last_allocated() {
+    if (!last_allocated_pid) {
+        return NULL;
+    }
+    return pid_get(last_allocated_pid);
+}
+
 struct task *task_create_(struct task *parent) {
     lock(&pids_lock);
-    static int cur_pid = 0;
     do {
-        cur_pid++;
-        if (cur_pid > MAX_PID) cur_pid = 1;
-    } while (!pid_empty(&pids[cur_pid]));
-    struct pid *pid = &pids[cur_pid];
-    pid->id = cur_pid;
+        last_allocated_pid++;
+        if (last_allocated_pid > MAX_PID) last_allocated_pid = 1;
+    } while (!pid_empty(&pids[last_allocated_pid]));
+    struct pid *pid = &pids[last_allocated_pid];
+    pid->id = last_allocated_pid;
     list_init(&pid->session);
     list_init(&pid->pgroup);
 
diff --git a/kernel/task.h b/kernel/task.h
index 6971040318..bb1c510651 100644
--- a/kernel/task.h
+++ b/kernel/task.h
@@ -171,6 +171,7 @@ struct pid {
 extern lock_t pids_lock;
 // these functions must be called with pids_lock
 struct pid *pid_get(dword_t pid);
+struct pid *pid_get_last_allocated(void);
 struct task *pid_get_task(dword_t pid);
 struct task *pid_get_task_zombie(dword_t id); // don't return null if the task exists as a zombie