kern/hlist: new module

3 files changed, 428 insertions, 0 deletions

diff --git a/Makefrag.am b/Makefrag.am
index a99f822e..51dadbe9 100644
--- a/Makefrag.am
+++ b/Makefrag.am
@@ -29,6 +29,8 @@ x15_SOURCES +=                                              \
         kern/error.c                                        \
         kern/error.h                                        \
         kern/hash.h                                         \
+        kern/hlist.h                                        \
+        kern/hlist_types.h                                  \
         kern/fmt.c                                          \
         kern/fmt.h                                          \
         kern/init.c                                         \
diff --git a/kern/hlist.h b/kern/hlist.h
new file mode 100644
index 00000000..0d5184b7
--- /dev/null
+++ b/kern/hlist.h
@@ -0,0 +1,386 @@
+/*
+ * Copyright (c) 2017 Richard Braun.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Doubly-linked list specialized for forward traversals and O(1) removals.
+ */
+
+#ifndef _KERN_HLIST_H
+#define _KERN_HLIST_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+#include <kern/hlist_types.h>
+#include <kern/llsync.h>
+#include <kern/macros.h>
+
+/*
+ * Static list initializer.
+ */
+#define HLIST_INITIALIZER(list) { NULL }
+
+/*
+ * Initialize a list.
+ */
+static inline void
+hlist_init(struct hlist *list)
+{
+    list->first = NULL;
+}
+
+/*
+ * Initialize a list node.
+ *
+ * A node is in no list when its pprev member points to NULL.
+ */
+static inline void
+hlist_node_init(struct hlist_node *node)
+{
+    node->pprev = NULL;
+}
+
+/*
+ * Return true if node is in no list.
+ */
+static inline bool
+hlist_node_unlinked(const struct hlist_node *node)
+{
+    return node->pprev == NULL;
+}
+
+/*
+ * Return the first node of a list.
+ */
+static inline struct hlist_node *
+hlist_first(const struct hlist *list)
+{
+    return list->first;
+}
+
+/*
+ * Return the node next to the given node.
+ */
+static inline struct hlist_node *
+hlist_next(const struct hlist_node *node)
+{
+    return node->next;
+}
+
+/*
+ * Return true if node is invalid and denotes the end of the list.
+ */
+static inline bool
+hlist_end(const struct hlist_node *node)
+{
+    return node == NULL;
+}
+
+/*
+ * Return true if list is empty.
+ */
+static inline bool
+hlist_empty(const struct hlist *list)
+{
+    return list->first == NULL;
+}
+
+/*
+ * Return true if list contains exactly one node.
+ */
+static inline bool
+hlist_singular(const struct hlist *list)
+{
+    return !hlist_empty(list) && hlist_end(list->first->next);
+}
+
+/*
+ * Set the new head of a list.
+ *
+ * After completion, old_head is stale.
+ */
+static inline void
+hlist_set_head(struct hlist *new_head, const struct hlist *old_head)
+{
+    *new_head = *old_head;
+
+    if (!hlist_empty(new_head)) {
+        new_head->first->pprev = &new_head->first;
+    }
+}
+
+/*
+ * Insert a node at the head of a list.
+ */
+static inline void
+hlist_insert_head(struct hlist *list, struct hlist_node *node)
+{
+    struct hlist_node *first;
+
+    first = list->first;
+    node->next = first;
+    node->pprev = &list->first;
+
+    if (first != NULL) {
+        first->pprev = &node->next;
+    }
+
+    list->first = node;
+}
+
+/*
+ * Insert a node before another node.
+ */
+static inline void
+hlist_insert_before(struct hlist_node *next, struct hlist_node *node)
+{
+    node->next = next;
+    node->pprev = next->pprev;
+    next->pprev = &node->next;
+    *node->pprev = node;
+}
+
+/*
+ * Insert a node after another node.
+ */
+static inline void
+hlist_insert_after(struct hlist_node *prev, struct hlist_node *node)
+{
+    node->next = prev->next;
+    node->pprev = &prev->next;
+
+    if (node->next != NULL) {
+        node->next->pprev = &node->next;
+    }
+
+    prev->next = node;
+}
+
+/*
+ * Remove a node from a list.
+ */
+static inline void
+hlist_remove(struct hlist_node *node)
+{
+    if (node->next != NULL) {
+        node->next->pprev = node->pprev;
+    }
+
+    *node->pprev = node->next;
+}
+
+/*
+ * Macro that evaluates to the address of the structure containing the
+ * given node based on the given type and member.
+ */
+#define hlist_entry(node, type, member) structof(node, type, member)
+
+/*
+ * Get the first entry of a list.
+ */
+#define hlist_first_entry(list, type, member)                           \
+MACRO_BEGIN                                                             \
+    struct hlist_node *___first;                                        \
+                                                                        \
+    ___first = (list)->first;                                           \
+    hlist_end(___first) ? NULL : hlist_entry(___first, type, member);   \
+MACRO_END
+
+/*
+ * Get the entry next to the given entry.
+ */
+#define hlist_next_entry(entry, member) \
+MACRO_BEGIN                                                             \
+    struct hlist_node *___next;                                         \
+                                                                        \
+    ___next = (entry)->member.next;                                     \
+    hlist_end(___next)                                                  \
+        ? NULL                                                          \
+        : hlist_entry(___next, typeof(*entry), member);                 \
+MACRO_END
+
+/*
+ * Forge a loop to process all nodes of a list.
+ *
+ * The node must not be altered during the loop.
+ */
+#define hlist_for_each(list, node)  \
+for (node = hlist_first(list);      \
+     !hlist_end(node);              \
+     node = hlist_next(node))
+
+/*
+ * Forge a loop to process all nodes of a list.
+ */
+#define hlist_for_each_safe(list, node, tmp)            \
+for (node = hlist_first(list),                          \
+     tmp = hlist_end(node) ? NULL : hlist_next(node);   \
+     !hlist_end(node);                                  \
+     node = tmp,                                        \
+     tmp = hlist_end(node) ? NULL : hlist_next(node))
+
+/*
+ * Forge a loop to process all entries of a list.
+ *
+ * The entry node must not be altered during the loop.
+ */
+#define hlist_for_each_entry(list, entry, member)               \
+for (entry = hlist_first_entry(list, typeof(*entry), member);   \
+     entry != NULL;                                             \
+     entry = hlist_next_entry(entry, member))
+
+/*
+ * Forge a loop to process all entries of a list.
+ */
+#define hlist_for_each_entry_safe(list, entry, tmp, member)             \
+for (entry = hlist_first_entry(list, typeof(*entry), member),           \
+     tmp = (entry == NULL) ? NULL : hlist_next_entry(entry, member);    \
+     entry != NULL;                                                     \
+     entry = tmp,                                                       \
+     tmp = (entry == NULL) ? NULL : hlist_next_entry(entry, member))    \
+
+/*
+ * Lockless variants
+ *
+ * The hlist_end() function may be used from read-side critical sections.
+ */
+
+/*
+ * Return the first node of a list.
+ */
+static inline struct hlist_node *
+hlist_llsync_first(const struct hlist *list)
+{
+    return llsync_read_ptr(list->first);
+}
+
+/*
+ * Return the node next to the given node.
+ */
+static inline struct hlist_node *
+hlist_llsync_next(const struct hlist_node *node)
+{
+    return llsync_read_ptr(node->next);
+}
+
+/*
+ * Insert a node at the head of a list.
+ */
+static inline void
+hlist_llsync_insert_head(struct hlist *list, struct hlist_node *node)
+{
+    struct hlist_node *first;
+
+    first = list->first;
+    node->next = first;
+    node->pprev = &list->first;
+
+    if (first != NULL) {
+        first->pprev = &node->next;
+    }
+
+    llsync_assign_ptr(list->first, node);
+}
+
+/*
+ * Insert a node before another node.
+ */
+static inline void
+hlist_llsync_insert_before(struct hlist_node *next, struct hlist_node *node)
+{
+    node->next = next;
+    node->pprev = next->pprev;
+    next->pprev = &node->next;
+    llsync_assign_ptr(*node->pprev, node);
+}
+
+/*
+ * Insert a node after another node.
+ */
+static inline void
+hlist_llsync_insert_after(struct hlist_node *prev, struct hlist_node *node)
+{
+    node->next = prev->next;
+    node->pprev = &prev->next;
+
+    if (node->next != NULL) {
+        node->next->pprev = &node->next;
+    }
+
+    llsync_assign_ptr(prev->next, node);
+}
+
+/*
+ * Remove a node from a list.
+ */
+static inline void
+hlist_llsync_remove(struct hlist_node *node)
+{
+    if (node->next != NULL) {
+        node->next->pprev = node->pprev;
+    }
+
+    llsync_assign_ptr(*node->pprev, node->next);
+}
+
+/*
+ * Macro that evaluates to the address of the structure containing the
+ * given node based on the given type and member.
+ */
+#define hlist_llsync_entry(node, type, member) \
+    structof(llsync_read_ptr(node), type, member)
+
+/*
+ * Get the first entry of a list.
+ */
+#define hlist_llsync_first_entry(list, type, member)                    \
+MACRO_BEGIN                                                             \
+    struct hlist_node *___first;                                        \
+                                                                        \
+    ___first = hlist_llsync_first(list);                                \
+    hlist_end(___first) ? NULL : hlist_entry(___first, type, member);   \
+MACRO_END
+
+/*
+ * Get the entry next to the given entry.
+ */
+#define hlist_llsync_next_entry(entry, member)                          \
+MACRO_BEGIN                                                             \
+    struct hlist_node *___next;                                         \
+                                                                        \
+    ___next = hlist_llsync_next(&entry->member);                        \
+    hlist_end(___next)                                                  \
+        ? NULL                                                          \
+        : hlist_entry(___next, typeof(*entry), member);                 \
+MACRO_END
+
+/*
+ * Forge a loop to process all nodes of a list.
+ */
+#define hlist_llsync_for_each(list, node)   \
+for (node = hlist_llsync_first(list);       \
+     !hlist_end(node);                      \
+     node = hlist_llsync_next(node))
+
+/*
+ * Forge a loop to process all entries of a list.
+ */
+#define hlist_llsync_for_each_entry(list, entry, member)                \
+for (entry = hlist_llsync_first_entry(list, typeof(*entry), member);    \
+     entry != NULL;                                                     \
+     entry = hlist_llsync_next_entry(entry, member))
+
+#endif /* _KERN_HLIST_H */
diff --git a/kern/hlist_types.h b/kern/hlist_types.h
new file mode 100644
index 00000000..f50b62db
--- /dev/null
+++ b/kern/hlist_types.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2017 Richard Braun.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Isolated type definition used to avoid inclusion circular dependencies.
+ */
+
+#ifndef _KERN_HLIST_TYPES_H
+#define _KERN_HLIST_TYPES_H
+
+/*
+ * List node.
+ *
+ * The pprev member points to another node member instead of another node,
+ * so that it may safely refer to the first member of the list head. Its
+ * main purpose is to allow O(1) removal.
+ */
+struct hlist_node {
+    struct hlist_node *next;
+    struct hlist_node **pprev;
+};
+
+struct hlist {
+    struct hlist_node *first;
+};
+
+#endif /* _KERN_HLIST_TYPES_H */