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 // 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/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);
 
 void trigger_data_free(struct event_trigger_data *data)
 {
     if (data->cmd_ops->set_filter)
         data->cmd_ops->set_filter(NULL, data, NULL);
 
     /* make sure current triggers exit before free */
     tracepoint_synchronize_unregister();
 
     kfree(data);
 }
 
 /**
  * event_triggers_call - Call triggers associated with a trace event
  * @file: The trace_event_file associated with the event
  * @rec: The trace entry for the event, NULL for unconditional invocation
  *
  * 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_data(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->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;
 
     mutex_lock(&event_mutex);
 
     if (unlikely(!event_file_data(file))) {
         mutex_unlock(&event_mutex);
         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;
         }
     }
 
     mutex_unlock(&event_mutex);
 
     return ret;
 }
 
 int trigger_process_regex(struct trace_event_file *file, char *buff)
 {
     char *command, *next;
     struct event_command *p;
     int ret = -EINVAL;
 
     next = buff = skip_spaces(buff);
     command = strsep(&next, ": \t");
     if (next) {
         next = skip_spaces(next);
         if (!*next)
             next = NULL;
     }
     command = (command[0] != '!') ? command : command + 1;
 
     mutex_lock(&trigger_cmd_mutex);
     list_for_each_entry(p, &trigger_commands, list) {
         if (strcmp(p->name, command) == 0) {
             ret = p->parse(p, file, buff, command, next);
             goto out_unlock;
         }
     }
  out_unlock:
     mutex_unlock(&trigger_cmd_mutex);
 
     return ret;
 }
 
 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;
 
     if (!cnt)
         return 0;
 
     if (cnt >= PAGE_SIZE)
         return -EINVAL;
 
     buf = memdup_user_nul(ubuf, cnt);
     if (IS_ERR(buf))
         return PTR_ERR(buf);
 
     strim(buf);
 
     mutex_lock(&event_mutex);
     event_file = event_file_data(file);
     if (unlikely(!event_file)) {
         mutex_unlock(&event_mutex);
         kfree(buf);
         return -ENODEV;
     }
     ret = trigger_process_regex(event_file, buf);
     mutex_unlock(&event_mutex);
 
     kfree(buf);
     if (ret < 0)
         goto out;
 
     *ppos += cnt;
     ret = cnt;
  out:
     return ret;
 }
 
 static int event_trigger_regex_release(struct inode *inode, struct file *file)
 {
     mutex_lock(&event_mutex);
 
     if (file->f_mode & FMODE_READ)
         seq_release(inode, file);
 
     mutex_unlock(&event_mutex);
 
     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;
     int ret = 0;
 
     mutex_lock(&trigger_cmd_mutex);
     list_for_each_entry(p, &trigger_commands, list) {
         if (strcmp(cmd->name, p->name) == 0) {
             ret = -EBUSY;
             goto out_unlock;
         }
     }
     list_add(&cmd->list, &trigger_commands);
  out_unlock:
     mutex_unlock(&trigger_cmd_mutex);
 
     return ret;
 }
 
 /*
  * 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;
     int ret = -ENODEV;
 
     mutex_lock(&trigger_cmd_mutex);
     list_for_each_entry_safe(p, n, &trigger_commands, list) {
         if (strcmp(cmd->name, p->name) == 0) {
             ret = 0;
             list_del_init(&p->list);
             goto out_unlock;
         }
     }
  out_unlock:
     mutex_unlock(&trigger_cmd_mutex);
 
     return ret;
 }
 
 /**
  * event_trigger_print - Generic event_trigger_ops @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_trigger_ops @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_trigger_ops @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->ops->free)
                 data->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) {
             ret = -EEXIST;
             goto out;
         }
     }
 
     if (data->ops->init) {
         ret = data->ops->init(data);
         if (ret < 0)
             goto out;
     }
 
     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);
     }
 out:
     return ret;
 }
 
 /**
  * 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)
 {
     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 && data->ops->free)
         data->ops->free(data);
 }
 
 /*
  * 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 componenents, 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;
         goto out;
     }
 
     /*
      * 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;
         goto out;
     }
 
     /*
      * 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;
     }
 out:
     return ret;
 }
 
 /**
  * event_trigger_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 are used along with the @cmd and @param to get the
  * trigger_ops to assign to the event_trigger_data.  @private_data can
  * also be passed in and associated with the event_trigger_data.
  *
  * Use event_trigger_free() to free an event_trigger_data object.
  *
  * Return: The trigger_data object success, NULL otherwise
  */
 struct event_trigger_data *event_trigger_alloc(struct event_command *cmd_ops,
                            char *cmd,
                            char *param,
                            void *private_data)
 {
     struct event_trigger_data *trigger_data;
     struct event_trigger_ops *trigger_ops;
 
     trigger_ops = cmd_ops->get_trigger_ops(cmd, param);
 
     trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
     if (!trigger_data)
         return NULL;
 
     trigger_data->count = -1;
     trigger_data->ops = trigger_ops;
     trigger_data->cmd_ops = cmd_ops;
     trigger_data->private_data = private_data;
 
     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 = event_trigger_alloc(cmd_ops, cmd, param, file);
     if (!trigger_data)
         goto out;
 
     if (remove) {
         event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
         kfree(trigger_data);
         ret = 0;
         goto out;
     }
 
     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);
  out:
     return ret;
 
  out_free:
     event_trigger_reset_filter(cmd_ops, trigger_data);
     kfree(trigger_data);
     goto out;
 }
 
 /**
  * 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)
         goto out;
 
     if (!filter_str)
         goto out;
 
     /* The filter is for the 'trigger' event, not the triggered event */
     ret = create_event_filter(file->tr, file->event_call,
                   filter_str, false, &filter);
     /*
      * 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 */
         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;
         }
     }
  out:
     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 (file) {
         if (tracer_tracing_is_on(file->tr))
             return;
 
         tracer_tracing_on(file->tr);
         return;
     }
 
     if (tracing_is_on())
         return;
 
     tracing_on();
 }
 
 static void
 traceon_count_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 (file) {
         if (tracer_tracing_is_on(file->tr))
             return;
     } else {
         if (tracing_is_on())
             return;
     }
 
     if (!data->count)
         return;
 
     if (data->count != -1)
         (data->count)--;
 
     if (file)
         tracer_tracing_on(file->tr);
     else
         tracing_on();
 }
 
 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 (file) {
         if (!tracer_tracing_is_on(file->tr))
             return;
 
         tracer_tracing_off(file->tr);
         return;
     }
 
     if (!tracing_is_on())
         return;
 
     tracing_off();
 }
 
 static void
 traceoff_count_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 (file) {
         if (!tracer_tracing_is_on(file->tr))
             return;
     } else {
         if (!tracing_is_on())
             return;
     }
 
     if (!data->count)
         return;
 
     if (data->count != -1)
         (data->count)--;
 
     if (file)
         tracer_tracing_off(file->tr);
     else
         tracing_off();
 }
 
 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_trigger_ops traceon_trigger_ops = {
     .trigger        = traceon_trigger,
     .print          = traceon_trigger_print,
     .init           = event_trigger_init,
     .free           = event_trigger_free,
 };
 
 static struct event_trigger_ops traceon_count_trigger_ops = {
     .trigger        = traceon_count_trigger,
     .print          = traceon_trigger_print,
     .init           = event_trigger_init,
     .free           = event_trigger_free,
 };
 
 static struct event_trigger_ops traceoff_trigger_ops = {
     .trigger        = traceoff_trigger,
     .print          = traceoff_trigger_print,
     .init           = event_trigger_init,
     .free           = event_trigger_free,
 };
 
 static struct event_trigger_ops traceoff_count_trigger_ops = {
     .trigger        = traceoff_count_trigger,
     .print          = traceoff_trigger_print,
     .init           = event_trigger_init,
     .free           = event_trigger_free,
 };
 
 static struct event_trigger_ops *
 onoff_get_trigger_ops(char *cmd, char *param)
 {
     struct event_trigger_ops *ops;
 
     /* we register both traceon and traceoff to this callback */
     if (strcmp(cmd, "traceon") == 0)
         ops = param ? &traceon_count_trigger_ops :
             &traceon_trigger_ops;
     else
         ops = param ? &traceoff_count_trigger_ops :
             &traceoff_trigger_ops;
 
     return ops;
 }
 
 static struct event_command trigger_traceon_cmd = {
     .name           = "traceon",
     .trigger_type       = ETT_TRACE_ONOFF,
     .parse          = event_trigger_parse,
     .reg            = register_trigger,
     .unreg          = unregister_trigger,
     .get_trigger_ops    = onoff_get_trigger_ops,
     .set_filter     = set_trigger_filter,
 };
 
 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,
     .get_trigger_ops    = onoff_get_trigger_ops,
     .set_filter     = set_trigger_filter,
 };
 
 #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 (file)
         tracing_snapshot_instance(file->tr);
     else
         tracing_snapshot();
 }
 
 static void
 snapshot_count_trigger(struct event_trigger_data *data,
                struct trace_buffer *buffer, void *rec,
                struct ring_buffer_event *event)
 {
     if (!data->count)
         return;
 
     if (data->count != -1)
         (data->count)--;
 
     snapshot_trigger(data, buffer, rec, event);
 }
 
 static int
 register_snapshot_trigger(char *glob,
               struct event_trigger_data *data,
               struct trace_event_file *file)
 {
     if (tracing_alloc_snapshot_instance(file->tr) != 0)
         return 0;
 
     return register_trigger(glob, data, file);
 }
 
 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_trigger_ops snapshot_trigger_ops = {
     .trigger        = snapshot_trigger,
     .print          = snapshot_trigger_print,
     .init           = event_trigger_init,
     .free           = event_trigger_free,
 };
 
 static struct event_trigger_ops snapshot_count_trigger_ops = {
     .trigger        = snapshot_count_trigger,
     .print          = snapshot_trigger_print,
     .init           = event_trigger_init,
     .free           = event_trigger_free,
 };
 
 static struct event_trigger_ops *
 snapshot_get_trigger_ops(char *cmd, char *param)
 {
     return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
 }
 
 static struct event_command trigger_snapshot_cmd = {
     .name           = "snapshot",
     .trigger_type       = ETT_SNAPSHOT,
     .parse          = event_trigger_parse,
     .reg            = register_snapshot_trigger,
     .unreg          = unregister_trigger,
     .get_trigger_ops    = snapshot_get_trigger_ops,
     .set_filter     = set_trigger_filter,
 };
 
 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 (file)
         __trace_stack(file->tr, tracing_gen_ctx(), STACK_SKIP);
     else
         trace_dump_stack(STACK_SKIP);
 }
 
 static void
 stacktrace_count_trigger(struct event_trigger_data *data,
              struct trace_buffer *buffer, void *rec,
              struct ring_buffer_event *event)
 {
     if (!data->count)
         return;
 
     if (data->count != -1)
         (data->count)--;
 
     stacktrace_trigger(data, buffer, rec, event);
 }
 
 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_trigger_ops stacktrace_trigger_ops = {
     .trigger        = stacktrace_trigger,
     .print          = stacktrace_trigger_print,
     .init           = event_trigger_init,
     .free           = event_trigger_free,
 };
 
 static struct event_trigger_ops stacktrace_count_trigger_ops = {
     .trigger        = stacktrace_count_trigger,
     .print          = stacktrace_trigger_print,
     .init           = event_trigger_init,
     .free           = event_trigger_free,
 };
 
 static struct event_trigger_ops *
 stacktrace_get_trigger_ops(char *cmd, char *param)
 {
     return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
 }
 
 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,
     .get_trigger_ops    = stacktrace_get_trigger_ops,
     .set_filter     = set_trigger_filter,
 };
 
 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 void
 event_enable_count_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 (!data->count)
         return;
 
     /* 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;
 
     if (data->count != -1)
         (data->count)--;
 
     event_enable_trigger(data, buffer, rec, event);
 }
 
 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);
     }
 }
 
 static struct event_trigger_ops event_enable_trigger_ops = {
     .trigger        = event_enable_trigger,
     .print          = event_enable_trigger_print,
     .init           = event_trigger_init,
     .free           = event_enable_trigger_free,
 };
 
 static struct event_trigger_ops event_enable_count_trigger_ops = {
     .trigger        = event_enable_count_trigger,
     .print          = event_enable_trigger_print,
     .init           = event_trigger_init,
     .free           = event_enable_trigger_free,
 };
 
 static struct event_trigger_ops event_disable_trigger_ops = {
     .trigger        = event_enable_trigger,
     .print          = event_enable_trigger_print,
     .init           = event_trigger_init,
     .free           = event_enable_trigger_free,
 };
 
 static struct event_trigger_ops event_disable_count_trigger_ops = {
     .trigger        = event_enable_count_trigger,
     .print          = event_enable_trigger_print,
     .init           = event_trigger_init,
     .free           = event_enable_trigger_free,
 };
 
 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)
         goto out;
 
 #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(sizeof(*enable_data), GFP_KERNEL);
     if (!enable_data)
         goto out;
 
     enable_data->hist = hist;
     enable_data->enable = enable;
     enable_data->file = event_enable_file;
 
     trigger_data = event_trigger_alloc(cmd_ops, cmd, param, enable_data);
     if (!trigger_data) {
         kfree(enable_data);
         goto out;
     }
 
     if (remove) {
         event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
         kfree(trigger_data);
         kfree(enable_data);
         ret = 0;
         goto out;
     }
 
     /* 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);
  out:
     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);
 
     goto out;
 }
 
 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)) {
             ret = -EEXIST;
             goto out;
         }
     }
 
     if (data->ops->init) {
         ret = data->ops->init(data);
         if (ret < 0)
             goto out;
     }
 
     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);
     }
 out:
     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->ops->free)
         data->ops->free(data);
 }
 
 static struct event_trigger_ops *
 event_enable_get_trigger_ops(char *cmd, char *param)
 {
     struct event_trigger_ops *ops;
     bool enable;
 
 #ifdef CONFIG_HIST_TRIGGERS
     enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
           (strcmp(cmd, ENABLE_HIST_STR) == 0));
 #else
     enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
 #endif
     if (enable)
         ops = param ? &event_enable_count_trigger_ops :
             &event_enable_trigger_ops;
     else
         ops = param ? &event_disable_count_trigger_ops :
             &event_disable_trigger_ops;
 
     return ops;
 }
 
 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,
     .get_trigger_ops    = event_enable_get_trigger_ops,
     .set_filter     = set_trigger_filter,
 };
 
 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,
     .get_trigger_ops    = event_enable_get_trigger_ops,
     .set_filter     = set_trigger_filter,
 };
 
 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;
 }

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