// SPDX-License-Identifier: GPL-2.0
/*
 * trace_events_trigger - trace event triggers
 *
 * Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>
 */

#include <linux/security.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/rculist.h>

#include "trace.h"

static LIST_HEAD(trigger_commands);
static DEFINE_MUTEX(trigger_cmd_mutex);

static struct task_struct *trigger_kthread;
static struct llist_head trigger_data_free_list;
static DEFINE_MUTEX(trigger_data_kthread_mutex);

static int trigger_kthread_fn(void *ignore);

static void trigger_create_kthread_locked(void)
{
        lockdep_assert_held(&trigger_data_kthread_mutex);

        if (!trigger_kthread) {
                struct task_struct *kthread;

                kthread = kthread_create(trigger_kthread_fn, NULL,
                                         "trigger_data_free");
                if (!IS_ERR(kthread))
                        WRITE_ONCE(trigger_kthread, kthread);
        }
}

static void trigger_data_free_queued_locked(void)
{
        struct event_trigger_data *data, *tmp;
        struct llist_node *llnodes;

        lockdep_assert_held(&trigger_data_kthread_mutex);

        llnodes = llist_del_all(&trigger_data_free_list);
        if (!llnodes)
                return;

        tracepoint_synchronize_unregister();

        llist_for_each_entry_safe(data, tmp, llnodes, llist)
                kfree(data);
}

/* Bulk garbage collection of event_trigger_data elements */
static int trigger_kthread_fn(void *ignore)
{
        struct event_trigger_data *data, *tmp;
        struct llist_node *llnodes;

        /* Once this task starts, it lives forever */
        for (;;) {
                set_current_state(TASK_INTERRUPTIBLE);
                if (llist_empty(&trigger_data_free_list))
                        schedule();

                __set_current_state(TASK_RUNNING);

                llnodes = llist_del_all(&trigger_data_free_list);

                /* make sure current triggers exit before free */
                tracepoint_synchronize_unregister();

                llist_for_each_entry_safe(data, tmp, llnodes, llist)
                        kfree(data);
        }

        return 0;
}

void trigger_data_free(struct event_trigger_data *data)
{
        if (!data)
                return;

        if (data->cmd_ops->set_filter)
                data->cmd_ops->set_filter(NULL, data, NULL);

        /*
         * Boot-time trigger registration can fail before kthread creation
         * works. Keep the deferred-free semantics during boot and let late
         * init start the kthread to drain the list.
         */
        if (system_state == SYSTEM_BOOTING && !trigger_kthread) {
                llist_add(&data->llist, &trigger_data_free_list);
                return;
        }

        if (unlikely(!trigger_kthread)) {
                guard(mutex)(&trigger_data_kthread_mutex);

                trigger_create_kthread_locked();
                /* Check again after taking mutex */
                if (!trigger_kthread) {
                        llist_add(&data->llist, &trigger_data_free_list);
                        /* Drain the queued frees synchronously if creation failed. */
                        trigger_data_free_queued_locked();
                        return;
                }
        }

        llist_add(&data->llist, &trigger_data_free_list);
        wake_up_process(trigger_kthread);
}

static int __init trigger_data_free_init(void)
{
        guard(mutex)(&trigger_data_kthread_mutex);

        if (llist_empty(&trigger_data_free_list))
                return 0;

        trigger_create_kthread_locked();
        if (trigger_kthread)
                wake_up_process(trigger_kthread);
        else
                trigger_data_free_queued_locked();

        return 0;
}
late_initcall(trigger_data_free_init);

static inline void data_ops_trigger(struct event_trigger_data *data,
                                    struct trace_buffer *buffer,  void *rec,
                                    struct ring_buffer_event *event)
{
        const struct event_command *cmd_ops = data->cmd_ops;

        if (data->flags & EVENT_TRIGGER_FL_COUNT) {
                if (!cmd_ops->count_func(data, buffer, rec, event))
                        return;
        }

        cmd_ops->trigger(data, buffer, rec, event);
}

/**
 * event_triggers_call - Call triggers associated with a trace event
 * @file: The trace_event_file associated with the event
 * @buffer: The ring buffer that the event is being written to
 * @rec: The trace entry for the event, NULL for unconditional invocation
 * @event: The event meta data in the ring buffer
 *
 * For each trigger associated with an event, invoke the trigger
 * function registered with the associated trigger command.  If rec is
 * non-NULL, it means that the trigger requires further processing and
 * shouldn't be unconditionally invoked.  If rec is non-NULL and the
 * trigger has a filter associated with it, rec will checked against
 * the filter and if the record matches the trigger will be invoked.
 * If the trigger is a 'post_trigger', meaning it shouldn't be invoked
 * in any case until the current event is written, the trigger
 * function isn't invoked but the bit associated with the deferred
 * trigger is set in the return value.
 *
 * Returns an enum event_trigger_type value containing a set bit for
 * any trigger that should be deferred, ETT_NONE if nothing to defer.
 *
 * Called from tracepoint handlers (with rcu_read_lock_sched() held).
 *
 * Return: an enum event_trigger_type value containing a set bit for
 * any trigger that should be deferred, ETT_NONE if nothing to defer.
 */
enum event_trigger_type
event_triggers_call(struct trace_event_file *file,
                    struct trace_buffer *buffer, void *rec,
                    struct ring_buffer_event *event)
{
        struct event_trigger_data *data;
        enum event_trigger_type tt = ETT_NONE;
        struct event_filter *filter;

        if (list_empty(&file->triggers))
                return tt;

        list_for_each_entry_rcu(data, &file->triggers, list) {
                if (data->paused)
                        continue;
                if (!rec) {
                        data_ops_trigger(data, buffer, rec, event);
                        continue;
                }
                filter = rcu_dereference_sched(data->filter);
                if (filter && !filter_match_preds(filter, rec))
                        continue;
                if (event_command_post_trigger(data->cmd_ops)) {
                        tt |= data->cmd_ops->trigger_type;
                        continue;
                }
                data_ops_trigger(data, buffer, rec, event);
        }
        return tt;
}
EXPORT_SYMBOL_GPL(event_triggers_call);

bool __trace_trigger_soft_disabled(struct trace_event_file *file)
{
        unsigned long eflags = file->flags;

        if (eflags & EVENT_FILE_FL_TRIGGER_MODE)
                event_triggers_call(file, NULL, NULL, NULL);
        if (eflags & EVENT_FILE_FL_SOFT_DISABLED)
                return true;
        if (eflags & EVENT_FILE_FL_PID_FILTER)
                return trace_event_ignore_this_pid(file);
        return false;
}
EXPORT_SYMBOL_GPL(__trace_trigger_soft_disabled);

/**
 * event_triggers_post_call - Call 'post_triggers' for a trace event
 * @file: The trace_event_file associated with the event
 * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
 *
 * For each trigger associated with an event, invoke the trigger
 * function registered with the associated trigger command, if the
 * corresponding bit is set in the tt enum passed into this function.
 * See @event_triggers_call for details on how those bits are set.
 *
 * Called from tracepoint handlers (with rcu_read_lock_sched() held).
 */
void
event_triggers_post_call(struct trace_event_file *file,
                         enum event_trigger_type tt)
{
        struct event_trigger_data *data;

        list_for_each_entry_rcu(data, &file->triggers, list) {
                if (data->paused)
                        continue;
                if (data->cmd_ops->trigger_type & tt)
                        data_ops_trigger(data, NULL, NULL, NULL);
        }
}
EXPORT_SYMBOL_GPL(event_triggers_post_call);

#define SHOW_AVAILABLE_TRIGGERS (void *)(1UL)

static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
{
        struct trace_event_file *event_file = event_file_data(m->private);

        if (t == SHOW_AVAILABLE_TRIGGERS) {
                (*pos)++;
                return NULL;
        }
        return seq_list_next(t, &event_file->triggers, pos);
}

static bool check_user_trigger(struct trace_event_file *file)
{
        struct event_trigger_data *data;

        list_for_each_entry_rcu(data, &file->triggers, list,
                                lockdep_is_held(&event_mutex)) {
                if (data->flags & EVENT_TRIGGER_FL_PROBE)
                        continue;
                return true;
        }
        return false;
}

static void *trigger_start(struct seq_file *m, loff_t *pos)
{
        struct trace_event_file *event_file;

        /* ->stop() is called even if ->start() fails */
        mutex_lock(&event_mutex);
        event_file = event_file_file(m->private);
        if (unlikely(!event_file))
                return ERR_PTR(-ENODEV);

        if (list_empty(&event_file->triggers) || !check_user_trigger(event_file))
                return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;

        return seq_list_start(&event_file->triggers, *pos);
}

static void trigger_stop(struct seq_file *m, void *t)
{
        mutex_unlock(&event_mutex);
}

static int trigger_show(struct seq_file *m, void *v)
{
        struct event_trigger_data *data;
        struct event_command *p;

        if (v == SHOW_AVAILABLE_TRIGGERS) {
                seq_puts(m, "# Available triggers:\n");
                seq_putc(m, '#');
                mutex_lock(&trigger_cmd_mutex);
                list_for_each_entry_reverse(p, &trigger_commands, list)
                        seq_printf(m, " %s", p->name);
                seq_putc(m, '\n');
                mutex_unlock(&trigger_cmd_mutex);
                return 0;
        }

        data = list_entry(v, struct event_trigger_data, list);
        data->cmd_ops->print(m, data);

        return 0;
}

static const struct seq_operations event_triggers_seq_ops = {
        .start = trigger_start,
        .next = trigger_next,
        .stop = trigger_stop,
        .show = trigger_show,
};

static int event_trigger_regex_open(struct inode *inode, struct file *file)
{
        int ret;

        ret = security_locked_down(LOCKDOWN_TRACEFS);
        if (ret)
                return ret;

        guard(mutex)(&event_mutex);

        if (unlikely(!event_file_file(file)))
                return -ENODEV;

        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC)) {
                struct trace_event_file *event_file;
                struct event_command *p;

                event_file = event_file_data(file);

                list_for_each_entry(p, &trigger_commands, list) {
                        if (p->unreg_all)
                                p->unreg_all(event_file);
                }
        }

        if (file->f_mode & FMODE_READ) {
                ret = seq_open(file, &event_triggers_seq_ops);
                if (!ret) {
                        struct seq_file *m = file->private_data;
                        m->private = file;
                }
        }

        return ret;
}

int trigger_process_regex(struct trace_event_file *file, char *buff)
{
        char *command, *next;
        struct event_command *p;

        next = buff = strim(buff);

        command = strsep(&next, ": \t");
        if (next) {
                next = skip_spaces(next);
                if (!*next)
                        next = NULL;
        }
        command = (command[0] != '!') ? command : command + 1;

        guard(mutex)(&trigger_cmd_mutex);

        list_for_each_entry(p, &trigger_commands, list) {
                if (strcmp(p->name, command) == 0)
                        return p->parse(p, file, buff, command, next);
        }

        return -EINVAL;
}

static ssize_t event_trigger_regex_write(struct file *file,
                                         const char __user *ubuf,
                                         size_t cnt, loff_t *ppos)
{
        struct trace_event_file *event_file;
        ssize_t ret;
        char *buf __free(kfree) = NULL;

        if (!cnt)
                return 0;

        if (cnt >= PAGE_SIZE)
                return -EINVAL;

        buf = memdup_user_nul(ubuf, cnt);
        if (IS_ERR(buf))
                return PTR_ERR(buf);

        guard(mutex)(&event_mutex);

        event_file = event_file_file(file);
        if (unlikely(!event_file))
                return -ENODEV;

        ret = trigger_process_regex(event_file, buf);
        if (ret < 0)
                return ret;

        *ppos += cnt;
        return cnt;
}

static int event_trigger_regex_release(struct inode *inode, struct file *file)
{
        if (file->f_mode & FMODE_READ)
                seq_release(inode, file);

        return 0;
}

static ssize_t
event_trigger_write(struct file *filp, const char __user *ubuf,
                    size_t cnt, loff_t *ppos)
{
        return event_trigger_regex_write(filp, ubuf, cnt, ppos);
}

static int
event_trigger_open(struct inode *inode, struct file *filp)
{
        /* Checks for tracefs lockdown */
        return event_trigger_regex_open(inode, filp);
}

static int
event_trigger_release(struct inode *inode, struct file *file)
{
        return event_trigger_regex_release(inode, file);
}

const struct file_operations event_trigger_fops = {
        .open = event_trigger_open,
        .read = seq_read,
        .write = event_trigger_write,
        .llseek = tracing_lseek,
        .release = event_trigger_release,
};

/*
 * Currently we only register event commands from __init, so mark this
 * __init too.
 */
__init int register_event_command(struct event_command *cmd)
{
        struct event_command *p;

        guard(mutex)(&trigger_cmd_mutex);

        list_for_each_entry(p, &trigger_commands, list) {
                if (strcmp(cmd->name, p->name) == 0)
                        return -EBUSY;
        }
        list_add(&cmd->list, &trigger_commands);

        return 0;
}

/*
 * Currently we only unregister event commands from __init, so mark
 * this __init too.
 */
__init int unregister_event_command(struct event_command *cmd)
{
        struct event_command *p, *n;

        guard(mutex)(&trigger_cmd_mutex);

        list_for_each_entry_safe(p, n, &trigger_commands, list) {
                if (strcmp(cmd->name, p->name) == 0) {
                        list_del_init(&p->list);
                        return 0;
                }
        }

        return -ENODEV;
}

/**
 * event_trigger_count - Optional count function for event triggers
 * @data: Trigger-specific data
 * @buffer: The ring buffer that the event is being written to
 * @rec: The trace entry for the event, NULL for unconditional invocation
 * @event: The event meta data in the ring buffer
 *
 * For triggers that can take a count parameter that doesn't do anything
 * special, they can use this function to assign to their .count_func
 * field.
 *
 * This simply does a count down of the @data->count field.
 *
 * If the @data->count is greater than zero, it will decrement it.
 *
 * Returns false if @data->count is zero, otherwise true.
 */
bool event_trigger_count(struct event_trigger_data *data,
                         struct trace_buffer *buffer,  void *rec,
                         struct ring_buffer_event *event)
{
        if (!data->count)
                return false;

        if (data->count != -1)
                (data->count)--;

        return true;
}

/**
 * event_trigger_print - Generic event_command @print implementation
 * @name: The name of the event trigger
 * @m: The seq_file being printed to
 * @data: Trigger-specific data
 * @filter_str: filter_str to print, if present
 *
 * Common implementation for event triggers to print themselves.
 *
 * Usually wrapped by a function that simply sets the @name of the
 * trigger command and then invokes this.
 *
 * Return: 0 on success, errno otherwise
 */
static int
event_trigger_print(const char *name, struct seq_file *m,
                    void *data, char *filter_str)
{
        long count = (long)data;

        seq_puts(m, name);

        if (count == -1)
                seq_puts(m, ":unlimited");
        else
                seq_printf(m, ":count=%ld", count);

        if (filter_str)
                seq_printf(m, " if %s\n", filter_str);
        else
                seq_putc(m, '\n');

        return 0;
}

/**
 * event_trigger_init - Generic event_command @init implementation
 * @data: Trigger-specific data
 *
 * Common implementation of event trigger initialization.
 *
 * Usually used directly as the @init method in event trigger
 * implementations.
 *
 * Return: 0 on success, errno otherwise
 */
int event_trigger_init(struct event_trigger_data *data)
{
        data->ref++;
        return 0;
}

/**
 * event_trigger_free - Generic event_command @free implementation
 * @data: Trigger-specific data
 *
 * Common implementation of event trigger de-initialization.
 *
 * Usually used directly as the @free method in event trigger
 * implementations.
 */
static void
event_trigger_free(struct event_trigger_data *data)
{
        if (WARN_ON_ONCE(data->ref <= 0))
                return;

        data->ref--;
        if (!data->ref)
                trigger_data_free(data);
}

int trace_event_trigger_enable_disable(struct trace_event_file *file,
                                       int trigger_enable)
{
        int ret = 0;

        if (trigger_enable) {
                if (atomic_inc_return(&file->tm_ref) > 1)
                        return ret;
                set_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
                ret = trace_event_enable_disable(file, 1, 1);
        } else {
                if (atomic_dec_return(&file->tm_ref) > 0)
                        return ret;
                clear_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
                ret = trace_event_enable_disable(file, 0, 1);
        }

        return ret;
}

/**
 * clear_event_triggers - Clear all triggers associated with a trace array
 * @tr: The trace array to clear
 *
 * For each trigger, the triggering event has its tm_ref decremented
 * via trace_event_trigger_enable_disable(), and any associated event
 * (in the case of enable/disable_event triggers) will have its sm_ref
 * decremented via free()->trace_event_enable_disable().  That
 * combination effectively reverses the soft-mode/trigger state added
 * by trigger registration.
 *
 * Must be called with event_mutex held.
 */
void
clear_event_triggers(struct trace_array *tr)
{
        struct trace_event_file *file;

        list_for_each_entry(file, &tr->events, list) {
                struct event_trigger_data *data, *n;
                list_for_each_entry_safe(data, n, &file->triggers, list) {
                        trace_event_trigger_enable_disable(file, 0);
                        list_del_rcu(&data->list);
                        if (data->cmd_ops->free)
                                data->cmd_ops->free(data);
                }
        }
}

/**
 * update_cond_flag - Set or reset the TRIGGER_COND bit
 * @file: The trace_event_file associated with the event
 *
 * If an event has triggers and any of those triggers has a filter or
 * a post_trigger, trigger invocation needs to be deferred until after
 * the current event has logged its data, and the event should have
 * its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
 * cleared.
 */
void update_cond_flag(struct trace_event_file *file)
{
        struct event_trigger_data *data;
        bool set_cond = false;

        lockdep_assert_held(&event_mutex);

        list_for_each_entry(data, &file->triggers, list) {
                if (data->filter || event_command_post_trigger(data->cmd_ops) ||
                    event_command_needs_rec(data->cmd_ops)) {
                        set_cond = true;
                        break;
                }
        }

        if (set_cond)
                set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
        else
                clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
}

/**
 * register_trigger - Generic event_command @reg implementation
 * @glob: The raw string used to register the trigger
 * @data: Trigger-specific data to associate with the trigger
 * @file: The trace_event_file associated with the event
 *
 * Common implementation for event trigger registration.
 *
 * Usually used directly as the @reg method in event command
 * implementations.
 *
 * Return: 0 on success, errno otherwise
 */
static int register_trigger(char *glob,
                            struct event_trigger_data *data,
                            struct trace_event_file *file)
{
        struct event_trigger_data *test;
        int ret = 0;

        lockdep_assert_held(&event_mutex);

        list_for_each_entry(test, &file->triggers, list) {
                if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type)
                        return -EEXIST;
        }

        if (data->cmd_ops->init) {
                ret = data->cmd_ops->init(data);
                if (ret < 0)
                        return ret;
        }

        list_add_rcu(&data->list, &file->triggers);

        update_cond_flag(file);
        ret = trace_event_trigger_enable_disable(file, 1);
        if (ret < 0) {
                list_del_rcu(&data->list);
                update_cond_flag(file);
        }
        return ret;
}

/*
 * True if the trigger was found and unregistered, else false.
 */
static bool try_unregister_trigger(char *glob,
                                   struct event_trigger_data *test,
                                   struct trace_event_file *file)
{
        struct event_trigger_data *data = NULL, *iter;

        lockdep_assert_held(&event_mutex);

        list_for_each_entry(iter, &file->triggers, list) {
                if (iter->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
                        data = iter;
                        list_del_rcu(&data->list);
                        trace_event_trigger_enable_disable(file, 0);
                        update_cond_flag(file);
                        break;
                }
        }

        if (data) {
                if (data->cmd_ops->free)
                        data->cmd_ops->free(data);

                return true;
        }

        return false;
}

/**
 * unregister_trigger - Generic event_command @unreg implementation
 * @glob: The raw string used to register the trigger
 * @test: Trigger-specific data used to find the trigger to remove
 * @file: The trace_event_file associated with the event
 *
 * Common implementation for event trigger unregistration.
 *
 * Usually used directly as the @unreg method in event command
 * implementations.
 */
static void unregister_trigger(char *glob,
                               struct event_trigger_data *test,
                               struct trace_event_file *file)
{
        try_unregister_trigger(glob, test, file);
}

/*
 * Event trigger parsing helper functions.
 *
 * These functions help make it easier to write an event trigger
 * parsing function i.e. the struct event_command.parse() callback
 * function responsible for parsing and registering a trigger command
 * written to the 'trigger' file.
 *
 * A trigger command (or just 'trigger' for short) takes the form:
 *   [trigger] [if filter]
 *
 * The struct event_command.parse() callback (and other struct
 * event_command functions) refer to several components of a trigger
 * command.  Those same components are referenced by the event trigger
 * parsing helper functions defined below.  These components are:
 *
 *   cmd               - the trigger command name
 *   glob              - the trigger command name optionally prefaced with '!'
 *   param_and_filter  - text following cmd and ':'
 *   param             - text following cmd and ':' and stripped of filter
 *   filter            - the optional filter text following (and including) 'if'
 *
 * To illustrate the use of these components, here are some concrete
 * examples. For the following triggers:
 *
 *   echo 'traceon:5 if pid == 0' > trigger
 *     - 'traceon' is both cmd and glob
 *     - '5 if pid == 0' is the param_and_filter
 *     - '5' is the param
 *     - 'if pid == 0' is the filter
 *
 *   echo 'enable_event:sys:event:n' > trigger
 *     - 'enable_event' is both cmd and glob
 *     - 'sys:event:n' is the param_and_filter
 *     - 'sys:event:n' is the param
 *     - there is no filter
 *
 *   echo 'hist:keys=pid if prio > 50' > trigger
 *     - 'hist' is both cmd and glob
 *     - 'keys=pid if prio > 50' is the param_and_filter
 *     - 'keys=pid' is the param
 *     - 'if prio > 50' is the filter
 *
 *   echo '!enable_event:sys:event:n' > trigger
 *     - 'enable_event' the cmd
 *     - '!enable_event' is the glob
 *     - 'sys:event:n' is the param_and_filter
 *     - 'sys:event:n' is the param
 *     - there is no filter
 *
 *   echo 'traceoff' > trigger
 *     - 'traceoff' is both cmd and glob
 *     - there is no param_and_filter
 *     - there is no param
 *     - there is no filter
 *
 * There are a few different categories of event trigger covered by
 * these helpers:
 *
 *  - triggers that don't require a parameter e.g. traceon
 *  - triggers that do require a parameter e.g. enable_event and hist
 *  - triggers that though they may not require a param may support an
 *    optional 'n' param (n = number of times the trigger should fire)
 *    e.g.: traceon:5 or enable_event:sys:event:n
 *  - triggers that do not support an 'n' param e.g. hist
 *
 * These functions can be used or ignored as necessary - it all
 * depends on the complexity of the trigger, and the granularity of
 * the functions supported reflects the fact that some implementations
 * may need to customize certain aspects of their implementations and
 * won't need certain functions.  For instance, the hist trigger
 * implementation doesn't use event_trigger_separate_filter() because
 * it has special requirements for handling the filter.
 */

/**
 * event_trigger_check_remove - check whether an event trigger specifies remove
 * @glob: The trigger command string, with optional remove(!) operator
 *
 * The event trigger callback implementations pass in 'glob' as a
 * parameter.  This is the command name either with or without a
 * remove(!)  operator.  This function simply parses the glob and
 * determines whether the command corresponds to a trigger removal or
 * a trigger addition.
 *
 * Return: true if this is a remove command, false otherwise
 */
bool event_trigger_check_remove(const char *glob)
{
        return (glob && glob[0] == '!') ? true : false;
}

/**
 * event_trigger_empty_param - check whether the param is empty
 * @param: The trigger param string
 *
 * The event trigger callback implementations pass in 'param' as a
 * parameter.  This corresponds to the string following the command
 * name minus the command name.  This function can be called by a
 * callback implementation for any command that requires a param; a
 * callback that doesn't require a param can ignore it.
 *
 * Return: true if this is an empty param, false otherwise
 */
bool event_trigger_empty_param(const char *param)
{
        return !param;
}

/**
 * event_trigger_separate_filter - separate an event trigger from a filter
 * @param_and_filter: String containing trigger and possibly filter
 * @param: outparam, will be filled with a pointer to the trigger
 * @filter: outparam, will be filled with a pointer to the filter
 * @param_required: Specifies whether or not the param string is required
 *
 * Given a param string of the form '[trigger] [if filter]', this
 * function separates the filter from the trigger and returns the
 * trigger in @param and the filter in @filter.  Either the @param
 * or the @filter may be set to NULL by this function - if not set to
 * NULL, they will contain strings corresponding to the trigger and
 * filter.
 *
 * There are two cases that need to be handled with respect to the
 * passed-in param: either the param is required, or it is not
 * required.  If @param_required is set, and there's no param, it will
 * return -EINVAL.  If @param_required is not set and there's a param
 * that starts with a number, that corresponds to the case of a
 * trigger with :n (n = number of times the trigger should fire) and
 * the parsing continues normally; otherwise the function just returns
 * and assumes param just contains a filter and there's nothing else
 * to do.
 *
 * Return: 0 on success, errno otherwise
 */
int event_trigger_separate_filter(char *param_and_filter, char **param,
                                  char **filter, bool param_required)
{
        int ret = 0;

        *param = *filter = NULL;

        if (!param_and_filter) {
                if (param_required)
                        ret = -EINVAL;
                return ret;
        }

        /*
         * Here we check for an optional param. The only legal
         * optional param is :n, and if that's the case, continue
         * below. Otherwise we assume what's left is a filter and
         * return it as the filter string for the caller to deal with.
         */
        if (!param_required && param_and_filter && !isdigit(param_and_filter[0])) {
                *filter = param_and_filter;
                return ret;
        }

        /*
         * Separate the param from the filter (param [if filter]).
         * Here we have either an optional :n param or a required
         * param and an optional filter.
         */
        *param = strsep(&param_and_filter, " \t");

        /*
         * Here we have a filter, though it may be empty.
         */
        if (param_and_filter) {
                *filter = skip_spaces(param_and_filter);
                if (!**filter)
                        *filter = NULL;
        }
        return ret;
}

/**
 * trigger_data_alloc - allocate and init event_trigger_data for a trigger
 * @cmd_ops: The event_command operations for the trigger
 * @cmd: The cmd string
 * @param: The param string
 * @private_data: User data to associate with the event trigger
 *
 * Allocate an event_trigger_data instance and initialize it.  The
 * @cmd_ops defines how the trigger will operate. If @param is set,
 * and @cmd_ops->trigger_ops->count_func is non NULL, then the
 * data->count is set to @param and before the trigger is executed, the
 * @cmd_ops->trigger_ops->count_func() is called. If that function returns
 * false, the @cmd_ops->trigger_ops->trigger() function will not be called.
 * @private_data can also be passed in and associated with the
 * event_trigger_data.
 *
 * Use trigger_data_free() to free an event_trigger_data object.
 *
 * Return: The trigger_data object success, NULL otherwise
 */
struct event_trigger_data *trigger_data_alloc(struct event_command *cmd_ops,
                                              char *cmd,
                                              char *param,
                                              void *private_data)
{
        struct event_trigger_data *trigger_data;

        trigger_data = kzalloc_obj(*trigger_data);
        if (!trigger_data)
                return NULL;

        trigger_data->count = -1;
        trigger_data->cmd_ops = cmd_ops;
        trigger_data->private_data = private_data;
        if (param && cmd_ops->count_func)
                trigger_data->flags |= EVENT_TRIGGER_FL_COUNT;

        INIT_LIST_HEAD(&trigger_data->list);
        INIT_LIST_HEAD(&trigger_data->named_list);
        RCU_INIT_POINTER(trigger_data->filter, NULL);

        return trigger_data;
}

/**
 * event_trigger_parse_num - parse and return the number param for a trigger
 * @param: The param string
 * @trigger_data: The trigger_data for the trigger
 *
 * Parse the :n (n = number of times the trigger should fire) param
 * and set the count variable in the trigger_data to the parsed count.
 *
 * Return: 0 on success, errno otherwise
 */
int event_trigger_parse_num(char *param,
                            struct event_trigger_data *trigger_data)
{
        char *number;
        int ret = 0;

        if (param) {
                number = strsep(&param, ":");

                if (!strlen(number))
                        return -EINVAL;

                /*
                 * We use the callback data field (which is a pointer)
                 * as our counter.
                 */
                ret = kstrtoul(number, 0, &trigger_data->count);
        }

        return ret;
}

/**
 * event_trigger_set_filter - set an event trigger's filter
 * @cmd_ops: The event_command operations for the trigger
 * @file: The event file for the trigger's event
 * @param: The string containing the filter
 * @trigger_data: The trigger_data for the trigger
 *
 * Set the filter for the trigger.  If the filter is NULL, just return
 * without error.
 *
 * Return: 0 on success, errno otherwise
 */
int event_trigger_set_filter(struct event_command *cmd_ops,
                             struct trace_event_file *file,
                             char *param,
                             struct event_trigger_data *trigger_data)
{
        if (param && cmd_ops->set_filter)
                return cmd_ops->set_filter(param, trigger_data, file);

        return 0;
}

/**
 * event_trigger_reset_filter - reset an event trigger's filter
 * @cmd_ops: The event_command operations for the trigger
 * @trigger_data: The trigger_data for the trigger
 *
 * Reset the filter for the trigger to no filter.
 */
void event_trigger_reset_filter(struct event_command *cmd_ops,
                                struct event_trigger_data *trigger_data)
{
        if (cmd_ops->set_filter)
                cmd_ops->set_filter(NULL, trigger_data, NULL);
}

/**
 * event_trigger_register - register an event trigger
 * @cmd_ops: The event_command operations for the trigger
 * @file: The event file for the trigger's event
 * @glob: The trigger command string, with optional remove(!) operator
 * @trigger_data: The trigger_data for the trigger
 *
 * Register an event trigger.  The @cmd_ops are used to call the
 * cmd_ops->reg() function which actually does the registration.
 *
 * Return: 0 on success, errno otherwise
 */
int event_trigger_register(struct event_command *cmd_ops,
                           struct trace_event_file *file,
                           char *glob,
                           struct event_trigger_data *trigger_data)
{
        return cmd_ops->reg(glob, trigger_data, file);
}

/**
 * event_trigger_unregister - unregister an event trigger
 * @cmd_ops: The event_command operations for the trigger
 * @file: The event file for the trigger's event
 * @glob: The trigger command string, with optional remove(!) operator
 * @trigger_data: The trigger_data for the trigger
 *
 * Unregister an event trigger.  The @cmd_ops are used to call the
 * cmd_ops->unreg() function which actually does the unregistration.
 */
void event_trigger_unregister(struct event_command *cmd_ops,
                              struct trace_event_file *file,
                              char *glob,
                              struct event_trigger_data *trigger_data)
{
        cmd_ops->unreg(glob, trigger_data, file);
}

/*
 * End event trigger parsing helper functions.
 */

/**
 * event_trigger_parse - Generic event_command @parse implementation
 * @cmd_ops: The command ops, used for trigger registration
 * @file: The trace_event_file associated with the event
 * @glob: The raw string used to register the trigger
 * @cmd: The cmd portion of the string used to register the trigger
 * @param_and_filter: The param and filter portion of the string used to register the trigger
 *
 * Common implementation for event command parsing and trigger
 * instantiation.
 *
 * Usually used directly as the @parse method in event command
 * implementations.
 *
 * Return: 0 on success, errno otherwise
 */
static int
event_trigger_parse(struct event_command *cmd_ops,
                    struct trace_event_file *file,
                    char *glob, char *cmd, char *param_and_filter)
{
        struct event_trigger_data *trigger_data;
        char *param, *filter;
        bool remove;
        int ret;

        remove = event_trigger_check_remove(glob);

        ret = event_trigger_separate_filter(param_and_filter, &param, &filter, false);
        if (ret)
                return ret;

        ret = -ENOMEM;
        trigger_data = trigger_data_alloc(cmd_ops, cmd, param, file);
        if (!trigger_data)
                return ret;

        if (remove) {
                event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
                trigger_data_free(trigger_data);
                return 0;
        }

        ret = event_trigger_parse_num(param, trigger_data);
        if (ret)
                goto out_free;

        ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
        if (ret < 0)
                goto out_free;

        /* Up the trigger_data count to make sure reg doesn't free it on failure */
        event_trigger_init(trigger_data);

        ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
        if (ret)
                goto out_free;

        /* Down the counter of trigger_data or free it if not used anymore */
        event_trigger_free(trigger_data);
        return ret;

 out_free:
        event_trigger_reset_filter(cmd_ops, trigger_data);
        trigger_data_free(trigger_data);
        return ret;
}

/**
 * set_trigger_filter - Generic event_command @set_filter implementation
 * @filter_str: The filter string for the trigger, NULL to remove filter
 * @trigger_data: Trigger-specific data
 * @file: The trace_event_file associated with the event
 *
 * Common implementation for event command filter parsing and filter
 * instantiation.
 *
 * Usually used directly as the @set_filter method in event command
 * implementations.
 *
 * Also used to remove a filter (if filter_str = NULL).
 *
 * Return: 0 on success, errno otherwise
 */
int set_trigger_filter(char *filter_str,
                       struct event_trigger_data *trigger_data,
                       struct trace_event_file *file)
{
        struct event_trigger_data *data = trigger_data;
        struct event_filter *filter = NULL, *tmp;
        int ret = -EINVAL;
        char *s;

        if (!filter_str) /* clear the current filter */
                goto assign;

        s = strsep(&filter_str, " \t");

        if (!strlen(s) || strcmp(s, "if") != 0)
                return ret;

        if (!filter_str)
                return ret;

        /* The filter is for the 'trigger' event, not the triggered event */
        ret = create_event_filter(file->tr, file->event_call,
                                  filter_str, true, &filter);

        /* Only enabled set_str for error handling */
        if (filter) {
                kfree(filter->filter_string);
                filter->filter_string = NULL;
        }

        /*
         * If create_event_filter() fails, filter still needs to be freed.
         * Which the calling code will do with data->filter.
         */
 assign:
        tmp = rcu_access_pointer(data->filter);

        rcu_assign_pointer(data->filter, filter);

        if (tmp) {
                /*
                 * Make sure the call is done with the filter.
                 * It is possible that a filter could fail at boot up,
                 * and then this path will be called. Avoid the synchronization
                 * in that case.
                 */
                if (system_state != SYSTEM_BOOTING)
                        tracepoint_synchronize_unregister();
                free_event_filter(tmp);
        }

        kfree(data->filter_str);
        data->filter_str = NULL;

        if (filter_str) {
                data->filter_str = kstrdup(filter_str, GFP_KERNEL);
                if (!data->filter_str) {
                        free_event_filter(rcu_access_pointer(data->filter));
                        data->filter = NULL;
                        ret = -ENOMEM;
                }
        }
        return ret;
}

static LIST_HEAD(named_triggers);

/**
 * find_named_trigger - Find the common named trigger associated with @name
 * @name: The name of the set of named triggers to find the common data for
 *
 * Named triggers are sets of triggers that share a common set of
 * trigger data.  The first named trigger registered with a given name
 * owns the common trigger data that the others subsequently
 * registered with the same name will reference.  This function
 * returns the common trigger data associated with that first
 * registered instance.
 *
 * Return: the common trigger data for the given named trigger on
 * success, NULL otherwise.
 */
struct event_trigger_data *find_named_trigger(const char *name)
{
        struct event_trigger_data *data;

        if (!name)
                return NULL;

        list_for_each_entry(data, &named_triggers, named_list) {
                if (data->named_data)
                        continue;
                if (strcmp(data->name, name) == 0)
                        return data;
        }

        return NULL;
}

/**
 * is_named_trigger - determine if a given trigger is a named trigger
 * @test: The trigger data to test
 *
 * Return: true if 'test' is a named trigger, false otherwise.
 */
bool is_named_trigger(struct event_trigger_data *test)
{
        struct event_trigger_data *data;

        list_for_each_entry(data, &named_triggers, named_list) {
                if (test == data)
                        return true;
        }

        return false;
}

/**
 * save_named_trigger - save the trigger in the named trigger list
 * @name: The name of the named trigger set
 * @data: The trigger data to save
 *
 * Return: 0 if successful, negative error otherwise.
 */
int save_named_trigger(const char *name, struct event_trigger_data *data)
{
        data->name = kstrdup(name, GFP_KERNEL);
        if (!data->name)
                return -ENOMEM;

        list_add(&data->named_list, &named_triggers);

        return 0;
}

/**
 * del_named_trigger - delete a trigger from the named trigger list
 * @data: The trigger data to delete
 */
void del_named_trigger(struct event_trigger_data *data)
{
        kfree(data->name);
        data->name = NULL;

        list_del(&data->named_list);
}

static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
{
        struct event_trigger_data *test;

        list_for_each_entry(test, &named_triggers, named_list) {
                if (strcmp(test->name, data->name) == 0) {
                        if (pause) {
                                test->paused_tmp = test->paused;
                                test->paused = true;
                        } else {
                                test->paused = test->paused_tmp;
                        }
                }
        }
}

/**
 * pause_named_trigger - Pause all named triggers with the same name
 * @data: The trigger data of a named trigger to pause
 *
 * Pauses a named trigger along with all other triggers having the
 * same name.  Because named triggers share a common set of data,
 * pausing only one is meaningless, so pausing one named trigger needs
 * to pause all triggers with the same name.
 */
void pause_named_trigger(struct event_trigger_data *data)
{
        __pause_named_trigger(data, true);
}

/**
 * unpause_named_trigger - Un-pause all named triggers with the same name
 * @data: The trigger data of a named trigger to unpause
 *
 * Un-pauses a named trigger along with all other triggers having the
 * same name.  Because named triggers share a common set of data,
 * unpausing only one is meaningless, so unpausing one named trigger
 * needs to unpause all triggers with the same name.
 */
void unpause_named_trigger(struct event_trigger_data *data)
{
        __pause_named_trigger(data, false);
}

/**
 * set_named_trigger_data - Associate common named trigger data
 * @data: The trigger data to associate
 * @named_data: The common named trigger to be associated
 *
 * Named triggers are sets of triggers that share a common set of
 * trigger data.  The first named trigger registered with a given name
 * owns the common trigger data that the others subsequently
 * registered with the same name will reference.  This function
 * associates the common trigger data from the first trigger with the
 * given trigger.
 */
void set_named_trigger_data(struct event_trigger_data *data,
                            struct event_trigger_data *named_data)
{
        data->named_data = named_data;
}

struct event_trigger_data *
get_named_trigger_data(struct event_trigger_data *data)
{
        return data->named_data;
}

static void
traceon_trigger(struct event_trigger_data *data,
                struct trace_buffer *buffer, void *rec,
                struct ring_buffer_event *event)
{
        struct trace_event_file *file = data->private_data;

        if (WARN_ON_ONCE(!file))
                return;

        if (tracer_tracing_is_on(file->tr))
                return;

        tracer_tracing_on(file->tr);
}

static bool
traceon_count_func(struct event_trigger_data *data,
                   struct trace_buffer *buffer, void *rec,
                   struct ring_buffer_event *event)
{
        struct trace_event_file *file = data->private_data;

        if (WARN_ON_ONCE(!file))
                return false;

        if (tracer_tracing_is_on(file->tr))
                return false;

        if (!data->count)
                return false;

        if (data->count != -1)
                (data->count)--;

        return true;
}

static void
traceoff_trigger(struct event_trigger_data *data,
                 struct trace_buffer *buffer, void *rec,
                 struct ring_buffer_event *event)
{
        struct trace_event_file *file = data->private_data;

        if (WARN_ON_ONCE(!file))
                return;

        if (!tracer_tracing_is_on(file->tr))
                return;

        tracer_tracing_off(file->tr);
}

static bool
traceoff_count_func(struct event_trigger_data *data,
                    struct trace_buffer *buffer, void *rec,
                    struct ring_buffer_event *event)
{
        struct trace_event_file *file = data->private_data;

        if (WARN_ON_ONCE(!file))
                return false;

        if (!tracer_tracing_is_on(file->tr))
                return false;

        if (!data->count)
                return false;

        if (data->count != -1)
                (data->count)--;

        return true;
}

static int
traceon_trigger_print(struct seq_file *m, struct event_trigger_data *data)
{
        return event_trigger_print("traceon", m, (void *)data->count,
                                   data->filter_str);
}

static int
traceoff_trigger_print(struct seq_file *m, struct event_trigger_data *data)
{
        return event_trigger_print("traceoff", m, (void *)data->count,
                                   data->filter_str);
}

static struct event_command trigger_traceon_cmd = {
        .name                   = "traceon",
        .trigger_type           = ETT_TRACE_ONOFF,
        .parse                  = event_trigger_parse,
        .reg                    = register_trigger,
        .unreg                  = unregister_trigger,
        .set_filter             = set_trigger_filter,
        .trigger                = traceon_trigger,
        .count_func             = traceon_count_func,
        .print                  = traceon_trigger_print,
        .init                   = event_trigger_init,
        .free                   = event_trigger_free,
};

static struct event_command trigger_traceoff_cmd = {
        .name                   = "traceoff",
        .trigger_type           = ETT_TRACE_ONOFF,
        .flags                  = EVENT_CMD_FL_POST_TRIGGER,
        .parse                  = event_trigger_parse,
        .reg                    = register_trigger,
        .unreg                  = unregister_trigger,
        .set_filter             = set_trigger_filter,
        .trigger                = traceoff_trigger,
        .count_func             = traceoff_count_func,
        .print                  = traceoff_trigger_print,
        .init                   = event_trigger_init,
        .free                   = event_trigger_free,
};

#ifdef CONFIG_TRACER_SNAPSHOT
static void
snapshot_trigger(struct event_trigger_data *data,
                 struct trace_buffer *buffer, void *rec,
                 struct ring_buffer_event *event)
{
        struct trace_event_file *file = data->private_data;

        if (WARN_ON_ONCE(!file))
                return;

        tracing_snapshot_instance(file->tr);
}

static int
register_snapshot_trigger(char *glob,
                          struct event_trigger_data *data,
                          struct trace_event_file *file)
{
        int ret = tracing_arm_snapshot(file->tr);

        if (ret < 0)
                return ret;

        ret = register_trigger(glob, data, file);
        if (ret < 0)
                tracing_disarm_snapshot(file->tr);
        return ret;
}

static void unregister_snapshot_trigger(char *glob,
                                        struct event_trigger_data *data,
                                        struct trace_event_file *file)
{
        if (try_unregister_trigger(glob, data, file))
                tracing_disarm_snapshot(file->tr);
}

static int
snapshot_trigger_print(struct seq_file *m, struct event_trigger_data *data)
{
        return event_trigger_print("snapshot", m, (void *)data->count,
                                   data->filter_str);
}

static struct event_command trigger_snapshot_cmd = {
        .name                   = "snapshot",
        .trigger_type           = ETT_SNAPSHOT,
        .parse                  = event_trigger_parse,
        .reg                    = register_snapshot_trigger,
        .unreg                  = unregister_snapshot_trigger,
        .set_filter             = set_trigger_filter,
        .trigger                = snapshot_trigger,
        .count_func             = event_trigger_count,
        .print                  = snapshot_trigger_print,
        .init                   = event_trigger_init,
        .free                   = event_trigger_free,
};

static __init int register_trigger_snapshot_cmd(void)
{
        int ret;

        ret = register_event_command(&trigger_snapshot_cmd);
        WARN_ON(ret < 0);

        return ret;
}
#else
static __init int register_trigger_snapshot_cmd(void) { return 0; }
#endif /* CONFIG_TRACER_SNAPSHOT */

#ifdef CONFIG_STACKTRACE
#ifdef CONFIG_UNWINDER_ORC
/* Skip 2:
 *   event_triggers_post_call()
 *   trace_event_raw_event_xxx()
 */
# define STACK_SKIP 2
#else
/*
 * Skip 4:
 *   stacktrace_trigger()
 *   event_triggers_post_call()
 *   trace_event_buffer_commit()
 *   trace_event_raw_event_xxx()
 */
#define STACK_SKIP 4
#endif

static void
stacktrace_trigger(struct event_trigger_data *data,
                   struct trace_buffer *buffer,  void *rec,
                   struct ring_buffer_event *event)
{
        struct trace_event_file *file = data->private_data;

        if (WARN_ON_ONCE(!file))
                return;

        __trace_stack(file->tr, tracing_gen_ctx_dec(), STACK_SKIP);
}

static int
stacktrace_trigger_print(struct seq_file *m, struct event_trigger_data *data)
{
        return event_trigger_print("stacktrace", m, (void *)data->count,
                                   data->filter_str);
}

static struct event_command trigger_stacktrace_cmd = {
        .name                   = "stacktrace",
        .trigger_type           = ETT_STACKTRACE,
        .flags                  = EVENT_CMD_FL_POST_TRIGGER,
        .parse                  = event_trigger_parse,
        .reg                    = register_trigger,
        .unreg                  = unregister_trigger,
        .set_filter             = set_trigger_filter,
        .trigger                = stacktrace_trigger,
        .count_func             = event_trigger_count,
        .print                  = stacktrace_trigger_print,
        .init                   = event_trigger_init,
        .free                   = event_trigger_free,
};

static __init int register_trigger_stacktrace_cmd(void)
{
        int ret;

        ret = register_event_command(&trigger_stacktrace_cmd);
        WARN_ON(ret < 0);

        return ret;
}
#else
static __init int register_trigger_stacktrace_cmd(void) { return 0; }
#endif /* CONFIG_STACKTRACE */

static __init void unregister_trigger_traceon_traceoff_cmds(void)
{
        unregister_event_command(&trigger_traceon_cmd);
        unregister_event_command(&trigger_traceoff_cmd);
}

static void
event_enable_trigger(struct event_trigger_data *data,
                     struct trace_buffer *buffer,  void *rec,
                     struct ring_buffer_event *event)
{
        struct enable_trigger_data *enable_data = data->private_data;

        if (enable_data->enable)
                clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
        else
                set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
}

static bool
event_enable_count_func(struct event_trigger_data *data,
                        struct trace_buffer *buffer,  void *rec,
                        struct ring_buffer_event *event)
{
        struct enable_trigger_data *enable_data = data->private_data;

        if (!data->count)
                return false;

        /* Skip if the event is in a state we want to switch to */
        if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
                return false;

        if (data->count != -1)
                (data->count)--;

        return true;
}

int event_enable_trigger_print(struct seq_file *m,
                               struct event_trigger_data *data)
{
        struct enable_trigger_data *enable_data = data->private_data;

        seq_printf(m, "%s:%s:%s",
                   enable_data->hist ?
                   (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
                   (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
                   enable_data->file->event_call->class->system,
                   trace_event_name(enable_data->file->event_call));

        if (data->count == -1)
                seq_puts(m, ":unlimited");
        else
                seq_printf(m, ":count=%ld", data->count);

        if (data->filter_str)
                seq_printf(m, " if %s\n", data->filter_str);
        else
                seq_putc(m, '\n');

        return 0;
}

void event_enable_trigger_free(struct event_trigger_data *data)
{
        struct enable_trigger_data *enable_data = data->private_data;

        if (WARN_ON_ONCE(data->ref <= 0))
                return;

        data->ref--;
        if (!data->ref) {
                /* Remove the SOFT_MODE flag */
                trace_event_enable_disable(enable_data->file, 0, 1);
                trace_event_put_ref(enable_data->file->event_call);
                trigger_data_free(data);
                kfree(enable_data);
        }
}

int event_enable_trigger_parse(struct event_command *cmd_ops,
                               struct trace_event_file *file,
                               char *glob, char *cmd, char *param_and_filter)
{
        struct trace_event_file *event_enable_file;
        struct enable_trigger_data *enable_data;
        struct event_trigger_data *trigger_data;
        struct trace_array *tr = file->tr;
        char *param, *filter;
        bool enable, remove;
        const char *system;
        const char *event;
        bool hist = false;
        int ret;

        remove = event_trigger_check_remove(glob);

        if (event_trigger_empty_param(param_and_filter))
                return -EINVAL;

        ret = event_trigger_separate_filter(param_and_filter, &param, &filter, true);
        if (ret)
                return ret;

        system = strsep(&param, ":");
        if (!param)
                return -EINVAL;

        event = strsep(&param, ":");

        ret = -EINVAL;
        event_enable_file = find_event_file(tr, system, event);
        if (!event_enable_file)
                return ret;

#ifdef CONFIG_HIST_TRIGGERS
        hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
                (strcmp(cmd, DISABLE_HIST_STR) == 0));

        enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
                  (strcmp(cmd, ENABLE_HIST_STR) == 0));
#else
        enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
#endif
        ret = -ENOMEM;

        enable_data = kzalloc_obj(*enable_data);
        if (!enable_data)
                return ret;

        enable_data->hist = hist;
        enable_data->enable = enable;
        enable_data->file = event_enable_file;

        trigger_data = trigger_data_alloc(cmd_ops, cmd, param, enable_data);
        if (!trigger_data) {
                kfree(enable_data);
                return ret;
        }

        if (remove) {
                event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
                kfree(trigger_data);
                kfree(enable_data);
                ret = 0;
                return ret;
        }

        /* Up the trigger_data count to make sure nothing frees it on failure */
        event_trigger_init(trigger_data);

        ret = event_trigger_parse_num(param, trigger_data);
        if (ret)
                goto out_free;

        ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
        if (ret < 0)
                goto out_free;

        /* Don't let event modules unload while probe registered */
        ret = trace_event_try_get_ref(event_enable_file->event_call);
        if (!ret) {
                ret = -EBUSY;
                goto out_free;
        }

        ret = trace_event_enable_disable(event_enable_file, 1, 1);
        if (ret < 0)
                goto out_put;

        ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
        if (ret)
                goto out_disable;

        event_trigger_free(trigger_data);
        return ret;
 out_disable:
        trace_event_enable_disable(event_enable_file, 0, 1);
 out_put:
        trace_event_put_ref(event_enable_file->event_call);
 out_free:
        event_trigger_reset_filter(cmd_ops, trigger_data);
        event_trigger_free(trigger_data);
        kfree(enable_data);

        return ret;
}

int event_enable_register_trigger(char *glob,
                                  struct event_trigger_data *data,
                                  struct trace_event_file *file)
{
        struct enable_trigger_data *enable_data = data->private_data;
        struct enable_trigger_data *test_enable_data;
        struct event_trigger_data *test;
        int ret = 0;

        lockdep_assert_held(&event_mutex);

        list_for_each_entry(test, &file->triggers, list) {
                test_enable_data = test->private_data;
                if (test_enable_data &&
                    (test->cmd_ops->trigger_type ==
                     data->cmd_ops->trigger_type) &&
                    (test_enable_data->file == enable_data->file)) {
                        return -EEXIST;
                }
        }

        if (data->cmd_ops->init) {
                ret = data->cmd_ops->init(data);
                if (ret < 0)
                        return ret;
        }

        list_add_rcu(&data->list, &file->triggers);

        update_cond_flag(file);
        ret = trace_event_trigger_enable_disable(file, 1);
        if (ret < 0) {
                list_del_rcu(&data->list);
                update_cond_flag(file);
        }
        return ret;
}

void event_enable_unregister_trigger(char *glob,
                                     struct event_trigger_data *test,
                                     struct trace_event_file *file)
{
        struct enable_trigger_data *test_enable_data = test->private_data;
        struct event_trigger_data *data = NULL, *iter;
        struct enable_trigger_data *enable_data;

        lockdep_assert_held(&event_mutex);

        list_for_each_entry(iter, &file->triggers, list) {
                enable_data = iter->private_data;
                if (enable_data &&
                    (iter->cmd_ops->trigger_type ==
                     test->cmd_ops->trigger_type) &&
                    (enable_data->file == test_enable_data->file)) {
                        data = iter;
                        list_del_rcu(&data->list);
                        trace_event_trigger_enable_disable(file, 0);
                        update_cond_flag(file);
                        break;
                }
        }

        if (data && data->cmd_ops->free)
                data->cmd_ops->free(data);
}

static struct event_command trigger_enable_cmd = {
        .name                   = ENABLE_EVENT_STR,
        .trigger_type           = ETT_EVENT_ENABLE,
        .parse                  = event_enable_trigger_parse,
        .reg                    = event_enable_register_trigger,
        .unreg                  = event_enable_unregister_trigger,
        .set_filter             = set_trigger_filter,
        .trigger                = event_enable_trigger,
        .count_func             = event_enable_count_func,
        .print                  = event_enable_trigger_print,
        .init                   = event_trigger_init,
        .free                   = event_enable_trigger_free,
};

static struct event_command trigger_disable_cmd = {
        .name                   = DISABLE_EVENT_STR,
        .trigger_type           = ETT_EVENT_ENABLE,
        .parse                  = event_enable_trigger_parse,
        .reg                    = event_enable_register_trigger,
        .unreg                  = event_enable_unregister_trigger,
        .set_filter             = set_trigger_filter,
        .trigger                = event_enable_trigger,
        .count_func             = event_enable_count_func,
        .print                  = event_enable_trigger_print,
        .init                   = event_trigger_init,
        .free                   = event_enable_trigger_free,
};

static __init void unregister_trigger_enable_disable_cmds(void)
{
        unregister_event_command(&trigger_enable_cmd);
        unregister_event_command(&trigger_disable_cmd);
}

static __init int register_trigger_enable_disable_cmds(void)
{
        int ret;

        ret = register_event_command(&trigger_enable_cmd);
        if (WARN_ON(ret < 0))
                return ret;
        ret = register_event_command(&trigger_disable_cmd);
        if (WARN_ON(ret < 0))
                unregister_trigger_enable_disable_cmds();

        return ret;
}

static __init int register_trigger_traceon_traceoff_cmds(void)
{
        int ret;

        ret = register_event_command(&trigger_traceon_cmd);
        if (WARN_ON(ret < 0))
                return ret;
        ret = register_event_command(&trigger_traceoff_cmd);
        if (WARN_ON(ret < 0))
                unregister_trigger_traceon_traceoff_cmds();

        return ret;
}

__init int register_trigger_cmds(void)
{
        register_trigger_traceon_traceoff_cmds();
        register_trigger_snapshot_cmd();
        register_trigger_stacktrace_cmd();
        register_trigger_enable_disable_cmds();
        register_trigger_hist_enable_disable_cmds();
        register_trigger_hist_cmd();

        return 0;
}