+++ /dev/null
-/*
- * lttng-tracker-pid.c
- *
- * LTTng Process ID trackering.
- *
- * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library 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
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/err.h>
-#include <linux/seq_file.h>
-#include <linux/stringify.h>
-#include <linux/hash.h>
-#include <linux/rcupdate.h>
-
-#include "wrapper/tracepoint.h"
-#include "wrapper/list.h"
-#include "lttng-events.h"
-
-/*
- * Hash table is allocated and freed when there are no possible
- * concurrent lookups (ensured by the alloc/free caller). However,
- * there can be concurrent RCU lookups vs add/del operations.
- *
- * Concurrent updates of the PID hash table are forbidden: the caller
- * must ensure mutual exclusion. This is currently done by holding the
- * sessions_mutex across calls to create, destroy, add, and del
- * functions of this API.
- */
-int lttng_pid_tracker_get_node_pid(const struct lttng_pid_hash_node *node)
-{
- return node->pid;
-}
-
-/*
- * Lookup performed from RCU read-side critical section (RCU sched),
- * protected by preemption off at the tracepoint call site.
- * Return 1 if found, 0 if not found.
- */
-bool lttng_pid_tracker_lookup(struct lttng_pid_tracker *lpf, int pid)
-{
- struct hlist_head *head;
- struct lttng_pid_hash_node *e;
- uint32_t hash = hash_32(pid, 32);
-
- head = &lpf->pid_hash[hash & (LTTNG_PID_TABLE_SIZE - 1)];
- lttng_hlist_for_each_entry_rcu_notrace(e, head, hlist) {
- if (pid == e->pid)
- return 1; /* Found */
- }
- return 0;
-}
-EXPORT_SYMBOL_GPL(lttng_pid_tracker_lookup);
-
-/*
- * Tracker add and del operations support concurrent RCU lookups.
- */
-int lttng_pid_tracker_add(struct lttng_pid_tracker *lpf, int pid)
-{
- struct hlist_head *head;
- struct lttng_pid_hash_node *e;
- uint32_t hash = hash_32(pid, 32);
-
- head = &lpf->pid_hash[hash & (LTTNG_PID_TABLE_SIZE - 1)];
- lttng_hlist_for_each_entry(e, head, hlist) {
- if (pid == e->pid)
- return -EEXIST;
- }
- e = kmalloc(sizeof(struct lttng_pid_hash_node), GFP_KERNEL);
- if (!e)
- return -ENOMEM;
- e->pid = pid;
- hlist_add_head_rcu(&e->hlist, head);
- return 0;
-}
-
-static
-void pid_tracker_del_node_rcu(struct lttng_pid_hash_node *e)
-{
- hlist_del_rcu(&e->hlist);
- /*
- * We choose to use a heavyweight synchronize on removal here,
- * since removal of a PID from the tracker mask is a rare
- * operation, and we don't want to use more cache lines than
- * what we really need when doing the PID lookups, so we don't
- * want to afford adding a rcu_head field to those pid hash
- * node.
- */
- synchronize_trace();
- kfree(e);
-}
-
-/*
- * This removal is only used on destroy, so it does not need to support
- * concurrent RCU lookups.
- */
-static
-void pid_tracker_del_node(struct lttng_pid_hash_node *e)
-{
- hlist_del(&e->hlist);
- kfree(e);
-}
-
-int lttng_pid_tracker_del(struct lttng_pid_tracker *lpf, int pid)
-{
- struct hlist_head *head;
- struct lttng_pid_hash_node *e;
- uint32_t hash = hash_32(pid, 32);
-
- head = &lpf->pid_hash[hash & (LTTNG_PID_TABLE_SIZE - 1)];
- /*
- * No need of _safe iteration, because we stop traversal as soon
- * as we remove the entry.
- */
- lttng_hlist_for_each_entry(e, head, hlist) {
- if (pid == e->pid) {
- pid_tracker_del_node_rcu(e);
- return 0;
- }
- }
- return -ENOENT; /* Not found */
-}
-
-struct lttng_pid_tracker *lttng_pid_tracker_create(void)
-{
- return kzalloc(sizeof(struct lttng_pid_tracker), GFP_KERNEL);
-}
-
-void lttng_pid_tracker_destroy(struct lttng_pid_tracker *lpf)
-{
- int i;
-
- for (i = 0; i < LTTNG_PID_TABLE_SIZE; i++) {
- struct hlist_head *head = &lpf->pid_hash[i];
- struct lttng_pid_hash_node *e;
- struct hlist_node *tmp;
-
- lttng_hlist_for_each_entry_safe(e, tmp, head, hlist)
- pid_tracker_del_node(e);
- }
- kfree(lpf);
-}
projects / lttng-modules.git / blobdiff