clist: add better debugging facilities

cmake/config.cmake

@@ -14,7 +14,9 @@ option(CFG_POISON_PAGES "Poison pages after allocate and free" ON)
 
 option(CFG_POISON_HEAP "Poison heap memory after kmalloc() and kfree()" ON)
 
-option(CFG_DEBUG_IRQ "Debug IRQs" ON)
+option(CFG_DEBUG_IRQ "Debug IRQs" ${DEBUG})
+
+option(CFG_DEBUG_CLIST "Sanitize clist operations" ${DEBUG})
 
 option(CFG_DEBUG_PAGE_ALLOCS "Debug page frame allocations" OFF)
 

include/gay/clist.h

@@ -7,6 +7,7 @@
 
 #pragma once
 
+#include <gay/config.h>
 #include <gay/util.h>
 
 /**
@@ -62,6 +63,26 @@ void clist_add_first(struct clist *head, struct clist *new);
  */
 void clist_del(struct clist *node);
 
+/**
+ * @brief Remove and return the first node in a clist.
+ * If the list is empty and `CFG_DEBUG_CLIST` is defined, this returns nil.
+ * If `CFG_DEBUG_CLIST` is not defined in this case, it will blow up.
+ *
+ * @param head Head of the list
+ * @return The deleted node
+ */
+struct clist *clist_del_first(struct clist *head);
+
+/**
+ * @brief Remove and return the last node in a clist.
+ * If the list is empty and `CFG_DEBUG_CLIST` is defined, this returns nil.
+ * If `CFG_DEBUG_CLIST` is not defined in this case, it will blow up.
+ *
+ * @param head Head of the list
+ * @return The deleted node
+ */
+struct clist *clist_del_last(struct clist *head);
+
 /**
  * @brief Return whether a clist is empty.
  *

include/gay/config.h.in

@@ -34,6 +34,9 @@
 /** @brief Debug IRQs */
 #cmakedefine01 CFG_DEBUG_IRQ
 
+/** @brief Sanitize clist operations */
+#cmakedefine01 CFG_DEBUG_CLIST
+
 /** @brief Debug page frame allocations */
 #cmakedefine01 CFG_DEBUG_PAGE_ALLOCS
 

include/gay/util.h

@@ -41,17 +41,11 @@
 #define container_of(ptr, type, member) \
 	((type *)( (void *)(ptr) - offsetof(type, member) ))
 
-/**
- * @brief Do an evil raw cast.
- *
- * @param type Type to cast to
- * @param expr Expression to cast
- * @returns The raw value of `expr`, cast to `type`
- */
-#define raw_cast(type, expr) ({		\
-	typeof(expr) __expr = (expr);	\
-	*(type *)&__expr;		\
-})
+/** @brief Determine whether `ptr` is kinda sus. */
+static __always_inline bool sus_nil(const void *ptr)
+{
+	return ptr < (void *)0x1000;
+}
 
 /**
  * @brief Align `ptr` such that `ptr % n == 0`.

kernel/clist.c

@@ -2,15 +2,32 @@
 
 #include <gay/clist.h>
 #include <gay/config.h>
+#include <gay/kprintf.h>
 
 void clist_init(struct clist *head)
 {
+#	if CFG_DEBUG_CLIST
+		if (head->next == head && head->prev == head)
+			kprintf("clist_init(%p) called multiple times\n", head);
+#	endif
+
 	head->next = head;
 	head->prev = head;
 }
 
 void clist_add(struct clist *head, struct clist *new)
 {
+#	if CFG_DEBUG_CLIST
+		if (sus_nil(head->next) || sus_nil(head->prev)) {
+			kprintf("clist_add(%p, %p): head seems uninitialized\n", head, new);
+			return;
+		}
+		if (sus_nil(new)) {
+			kprintf("clist_add(%p, %p): new node is NULL!\n", head, new);
+			return;
+		}
+#	endif
+
 	head->prev->next = new;
 	new->next = head;
 
@@ -32,12 +49,40 @@ void clist_del(struct clist *node)
 	node->next->prev = node->prev;
 	node->prev->next = node->next;
 
-#	ifdef DEBUG
-		node->next = NULL;
-		node->prev = NULL;
+#	if CFG_DEBUG_CLIST
+		node->next = nil;
+		node->prev = nil;
 #	endif
 }
 
+struct clist *clist_del_first(struct clist *head)
+{
+#	if CFG_DEBUG_CLIST
+		if (clist_is_empty(head)) {
+			kprintf("clist_del_first(%p): empty list!\n", head);
+			return nil;
+		}
+#	endif
+
+	struct clist *first = head->next;
+	clist_del(first);
+	return first;
+}
+
+struct clist *clist_del_last(struct clist *head)
+{
+#	ifdef CFG_DEBUG_CLIST
+		if (clist_is_empty(head)) {
+			kprintf("clist_del_last(%p): empty list!\n", head);
+			return nil;
+		}
+#	endif
+
+	struct clist *last = head->prev;
+	clist_del(last);
+	return last;
+}
+
 /*
  * This file is part of GayBSD.
  * Copyright (c) 2021 fef <owo@fef.moe>.