From b6d2cfb9b3f08dd7627fe1924449ff06c548efbe Mon Sep 17 00:00:00 2001
From: Mark <alnyan@airmail.cc>
Date: Mon, 3 Feb 2020 13:59:00 +0200
Subject: [PATCH] Better cleanup of dead threads

---
 sys/sched.c  | 33 +++++++++++++++++++++++
 sys/thread.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 107 insertions(+), 1 deletion(-)

diff --git a/sys/sched.c b/sys/sched.c
index f2714fb..9dd78e0 100644
--- a/sys/sched.c
+++ b/sys/sched.c
@@ -1,4 +1,6 @@
 #include "sys/amd64/context.h"
+#include "sys/amd64/mm/pool.h"
+#include "sys/amd64/mm/phys.h"
 #include "sys/amd64/hw/irq.h"
 #include "sys/amd64/hw/idt.h"
 #include "sys/user/signum.h"
@@ -8,6 +10,7 @@
 #include "sys/thread.h"
 #include "sys/sched.h"
 #include "sys/debug.h"
+#include "sys/heap.h"
 #include "sys/mm.h"
 
 void yield(void);
@@ -146,6 +149,12 @@ void sched_debug_cycle(uint64_t delta_ms) {
     struct thread *thr = queue_head;
     extern struct thread user_init;
 
+    struct heap_stat st;
+    struct amd64_phys_stat phys_st;
+    struct amd64_pool_stat pool_st;
+
+    kdebug("--- DEBUG_CYCLE ---\n");
+
     debugs(DEBUG_DEFAULT, "Process tree:\n");
     sched_debug_tree(DEBUG_DEFAULT, &user_init, 0);
 
@@ -167,6 +176,30 @@ void sched_debug_cycle(uint64_t delta_ms) {
     } else {
         kdebug("--- IDLE\n");
     }
+
+    heap_stat(heap_global, &st);
+    kdebug("Heap stat:\n");
+    kdebug("Allocated blocks: %u\n", st.alloc_count);
+    kdebug("Used %S, free %S, total %S\n", st.alloc_size, st.free_size, st.total_size);
+
+    amd64_phys_stat(&phys_st);
+    kdebug("Physical memory:\n");
+    kdebug("Used %S (%u), free %S (%u), ceiling %p\n",
+            phys_st.pages_used * 0x1000,
+            phys_st.pages_used,
+            phys_st.pages_free * 0x1000,
+            phys_st.pages_free,
+            phys_st.limit);
+
+    amd64_mm_pool_stat(&pool_st);
+    kdebug("Paging pool:\n");
+    kdebug("Used %S (%u), free %S (%u)\n",
+            pool_st.pages_used * 0x1000,
+            pool_st.pages_used,
+            pool_st.pages_free * 0x1000,
+            pool_st.pages_free);
+
+    kdebug("--- ----------- ---\n");
 }
 
 void yield(void) {
diff --git a/sys/thread.c b/sys/thread.c
index 129b77f..cefac08 100644
--- a/sys/thread.c
+++ b/sys/thread.c
@@ -57,6 +57,24 @@ static void thread_add(struct thread *thr) {
     threads_all_head = thr;
 }
 
+static void thread_remove(struct thread *thr) {
+    struct thread *prev = thr->g_prev;
+    struct thread *next = thr->g_next;
+
+    if (prev) {
+        prev->g_next = next;
+    } else {
+        threads_all_head = next;
+    }
+
+    if (next) {
+        next->g_prev = prev;
+    }
+
+    thr->g_next = NULL;
+    thr->g_prev = NULL;
+}
+
 ////
 
 static void thread_ioctx_empty(struct thread *thr) {
@@ -113,6 +131,32 @@ struct thread *thread_child(struct thread *of, pid_t pid) {
     return NULL;
 }
 
+void thread_unchild(struct thread *thr) {
+    struct thread *par = thr->parent;
+    _assert(par);
+
+    struct thread *p = NULL;
+    struct thread *c = par->first_child;
+    int found = 0;
+
+    while (c) {
+        if (c == thr) {
+            found = 1;
+            if (p) {
+                p->next_child = thr->next_child;
+            } else {
+                par->first_child = thr->next_child;
+            }
+            break;
+        }
+
+        p = c;
+        c = c->next_child;
+    }
+
+    _assert(found);
+}
+
 void thread_cleanup(struct thread *thr) {
     _assert(thr);
     // Leave only the system context required for hierachy tracking and error code/pid
@@ -136,6 +180,30 @@ void thread_cleanup(struct thread *thr) {
     mm_space_release(thr->space);
 }
 
+void thread_free(struct thread *thr) {
+    _assert(thr->flags & THREAD_STOPPED);
+    _assert(thr->flags & THREAD_EMPTY);
+
+    // Free kstack
+    for (size_t i = 0; i < thr->data.rsp0_size / MM_PAGE_SIZE; ++i) {
+        amd64_phys_free(MM_PHYS(i * MM_PAGE_SIZE + thr->data.rsp0_base));
+    }
+
+    // Free page directory (if not mm_kernel)
+    if (thr->space != mm_kernel) {
+        // Make sure we don't shoot a leg off
+        uintptr_t cr3;
+        asm volatile ("movq %%cr3, %0":"=a"(cr3));
+        _assert(MM_VIRTUALIZE(cr3) != (uintptr_t) thr->space);
+
+        mm_space_free(thr->space);
+    }
+
+    // Free thread itself
+    memset(thr, 0, sizeof(struct thread));
+    kfree(thr);
+}
+
 int thread_init(struct thread *thr, uintptr_t entry, void *arg, int user) {
     uintptr_t stack_pages = amd64_phys_alloc_contiguous(2);
     _assert(stack_pages != MM_NADDR);
@@ -552,11 +620,16 @@ int sys_waitpid(pid_t pid, int *status) {
         thread_check_signal(thr, 0);
     }
 
+    // Make sure no platform context remains
+    _assert(chld->flags & THREAD_EMPTY);
+
     if (status) {
         *status = chld->exit_status;
     }
 
-    // TODO: Cleanup the child here
+    thread_unchild(chld);
+    thread_remove(chld);
+    thread_free(chld);
 
     return 0;
 }