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subr_pctrie: add leaf callbacks to pctrie_reclaim

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PCTRIE_RECLAIM frees all the interior nodes in a pctrie, but is little
used because most trie-destroyers want to free leaves of the tree
too. Add PCTRIE_RECLAIM_CALLBACK, with two extra arguments, a callback
function and an auxiliary argument, that is invoked on every non-NULL
leaf in the tree as the tree is destroyed.

Reviewed by:	rlibby, kib (previous version)
Differential Revision:	https://reviews.freebsd.org/D45565
This commit is contained in:
Doug Moore 2024-06-13 11:44:38 -05:00
parent a16cb8709d
commit c0d0bc2bed
2 changed files with 85 additions and 18 deletions
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78
sys/kern/subr_pctrie.c
View File

@ -198,7 +198,6 @@ pctrie_root_store(struct pctrie *ptree, struct pctrie_node *node,
static __inline bool
pctrie_isleaf(struct pctrie_node *node)
{
return (((uintptr_t)node & PCTRIE_ISLEAF) != 0);
}
@ -217,10 +216,18 @@ pctrie_toleaf(uint64_t *val)
static __inline uint64_t *
pctrie_toval(struct pctrie_node *node)
{
return ((uint64_t *)((uintptr_t)node & ~PCTRIE_FLAGS));
}
/*
* Returns the associated pointer extracted from node and field offset.
*/
static __inline void *
pctrie_toptr(struct pctrie_node *node, int keyoff)
{
return ((void *)(((uintptr_t)node & ~PCTRIE_FLAGS) - keyoff));
}
/*
* Make 'child' a child of 'node'.
*/
@ -792,14 +799,14 @@ pctrie_remove_lookup(struct pctrie *ptree, uint64_t index,
}
/*
* Prune all the leaves of 'node' before its first non-leaf child, make child
* zero of 'node' point up to 'parent', make 'node' into 'parent' and that
* non-leaf child into 'node'. Repeat until a node has been stripped of all
* children, and mark it for freeing, returning its parent.
* Walk the subtrie rooted at *pnode in order, invoking callback on leaves and
* using the leftmost child pointer for path reversal, until an interior node
* is stripped of all children, and returned for deallocation, with *pnode left
* pointing the parent of that node.
*/
static struct pctrie_node *
pctrie_reclaim_prune(struct pctrie_node **pnode,
struct pctrie_node *parent)
static __always_inline struct pctrie_node *
pctrie_reclaim_prune(struct pctrie_node **pnode, struct pctrie_node *parent,
pctrie_cb_t callback, int keyoff, void *arg)
{
struct pctrie_node *child, *node;
int slot;
@ -812,8 +819,11 @@ pctrie_reclaim_prune(struct pctrie_node **pnode,
PCTRIE_UNSERIALIZED);
pctrie_node_store(&node->pn_child[slot], PCTRIE_NULL,
PCTRIE_UNSERIALIZED);
if (pctrie_isleaf(child))
if (pctrie_isleaf(child)) {
if (callback != NULL)
callback(pctrie_toptr(child, keyoff), arg);
continue;
}
/* Climb one level down the trie. */
pctrie_node_store(&node->pn_child[0], parent,
PCTRIE_UNSERIALIZED);
@ -827,8 +837,9 @@ pctrie_reclaim_prune(struct pctrie_node **pnode,
/*
* Recover the node parent from its first child and continue pruning.
*/
struct pctrie_node *
pctrie_reclaim_resume(struct pctrie_node **pnode)
static __always_inline struct pctrie_node *
pctrie_reclaim_resume_compound(struct pctrie_node **pnode,
pctrie_cb_t callback, int keyoff, void *arg)
{
struct pctrie_node *parent, *node;
@ -839,24 +850,55 @@ pctrie_reclaim_resume(struct pctrie_node **pnode)
parent = pctrie_node_load(&node->pn_child[0], NULL,
PCTRIE_UNSERIALIZED);
pctrie_node_store(&node->pn_child[0], PCTRIE_NULL, PCTRIE_UNSERIALIZED);
return (pctrie_reclaim_prune(pnode, parent));
return (pctrie_reclaim_prune(pnode, parent, callback, keyoff, arg));
}
/*
* Find the trie root, and start pruning with a NULL parent.
*/
struct pctrie_node *
pctrie_reclaim_begin(struct pctrie_node **pnode,
struct pctrie *ptree)
static __always_inline struct pctrie_node *
pctrie_reclaim_begin_compound(struct pctrie_node **pnode,
struct pctrie *ptree,
pctrie_cb_t callback, int keyoff, void *arg)
{
struct pctrie_node *node;
node = pctrie_root_load(ptree, NULL, PCTRIE_UNSERIALIZED);
pctrie_root_store(ptree, PCTRIE_NULL, PCTRIE_UNSERIALIZED);
if (pctrie_isleaf(node))
if (pctrie_isleaf(node)) {
if (callback != NULL && node != PCTRIE_NULL)
callback(pctrie_toptr(node, keyoff), arg);
return (NULL);
}
*pnode = node;
return (pctrie_reclaim_prune(pnode, NULL));
return (pctrie_reclaim_prune(pnode, NULL, callback, keyoff, arg));
}
struct pctrie_node *
pctrie_reclaim_resume(struct pctrie_node **pnode)
{
return (pctrie_reclaim_resume_compound(pnode, NULL, 0, NULL));
}
struct pctrie_node *
pctrie_reclaim_begin(struct pctrie_node **pnode, struct pctrie *ptree)
{
return (pctrie_reclaim_begin_compound(pnode, ptree, NULL, 0, NULL));
}
struct pctrie_node *
pctrie_reclaim_resume_cb(struct pctrie_node **pnode,
pctrie_cb_t callback, int keyoff, void *arg)
{
return (pctrie_reclaim_resume_compound(pnode, callback, keyoff, arg));
}
struct pctrie_node *
pctrie_reclaim_begin_cb(struct pctrie_node **pnode, struct pctrie *ptree,
pctrie_cb_t callback, int keyoff, void *arg)
{
return (pctrie_reclaim_begin_compound(pnode, ptree,
callback, keyoff, arg));
}
/*

25
sys/sys/pctrie.h
View File

@ -36,6 +36,8 @@
#ifdef _KERNEL
typedef void (*pctrie_cb_t)(void *ptr, void *arg);
#define PCTRIE_DEFINE_SMR(name, type, field, allocfn, freefn, smr) \
PCTRIE_DEFINE(name, type, field, allocfn, freefn) \
\
@ -218,6 +220,24 @@ name##_PCTRIE_RECLAIM(struct pctrie *ptree) \
freefn(ptree, freenode); \
} \
\
/* \
* While reclaiming all internal trie nodes, invoke callback(leaf, arg) \
* on every leaf in the trie, in order. \
*/ \
static __inline __unused void \
name##_PCTRIE_RECLAIM_CALLBACK(struct pctrie *ptree, \
pctrie_cb_t callback, void *arg) \
{ \
struct pctrie_node *freenode, *node; \
\
for (freenode = pctrie_reclaim_begin_cb(&node, ptree, \
callback, __offsetof(struct type, field), arg); \
freenode != NULL; \
freenode = pctrie_reclaim_resume_cb(&node, \
callback, __offsetof(struct type, field), arg)) \
freefn(ptree, freenode); \
} \
\
static __inline __unused struct type * \
name##_PCTRIE_REPLACE(struct pctrie *ptree, struct type *ptr) \
{ \
@ -269,6 +289,11 @@ uint64_t *pctrie_lookup_unlocked(struct pctrie *ptree, uint64_t key,
struct pctrie_node *pctrie_reclaim_begin(struct pctrie_node **pnode,
struct pctrie *ptree);
struct pctrie_node *pctrie_reclaim_resume(struct pctrie_node **pnode);
struct pctrie_node *pctrie_reclaim_begin_cb(struct pctrie_node **pnode,
struct pctrie *ptree,
pctrie_cb_t callback, int keyoff, void *arg);
struct pctrie_node *pctrie_reclaim_resume_cb(struct pctrie_node **pnode,
pctrie_cb_t callback, int keyoff, void *arg);
uint64_t *pctrie_remove_lookup(struct pctrie *ptree, uint64_t index,
struct pctrie_node **killnode);
uint64_t *pctrie_replace(struct pctrie *ptree, uint64_t *newval);