// SPDX-License-Identifier: GPL-2.0/* * Generic dynamic event control interface * * Copyright (C) 2018 Masami Hiramatsu <mhiramat@kernel.org> */ #include <linux/debugfs.h>#include <linux/kernel.h>#include <linux/list.h>#include <linux/mm.h>#include <linux/mutex.h>#include <linux/tracefs.h> #include "trace.h"#include "trace_dynevent.h" static DEFINE_MUTEX(dyn_event_ops_mutex);static LIST_HEAD(dyn_event_ops_list); int dyn_event_register(struct dyn_event_operations *ops){	if (!ops || !ops->create || !ops->show || !ops->is_busy ||	    !ops->free || !ops->match)		return -EINVAL; 	INIT_LIST_HEAD(&ops->list);	mutex_lock(&dyn_event_ops_mutex);	list_add_tail(&ops->list, &dyn_event_ops_list);	mutex_unlock(&dyn_event_ops_mutex);	return 0;} int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type){	struct dyn_event *pos, *n;	char *system = NULL, *event, *p;	int ret = -ENOENT; 	if (argv[0][0] == '-') {		if (argv[0][1] != ':')			return -EINVAL;		event = &argv[0][2];	} else {		event = strchr(argv[0], ':');		if (!event)			return -EINVAL;		event++;	} 	p = strchr(event, '/');	if (p) {		system = event;		event = p + 1;		*p = '\0';	}	if (event[0] == '\0')		return -EINVAL; 	mutex_lock(&event_mutex);	for_each_dyn_event_safe(pos, n) {		if (type && type != pos->ops)			continue;		if (pos->ops->match(system, event, pos)) {			ret = pos->ops->free(pos);			break;		}	}	mutex_unlock(&event_mutex); 	return ret;} static int create_dyn_event(int argc, char **argv){	struct dyn_event_operations *ops;	int ret = -ENODEV; 	if (argv[0][0] == '-' || argv[0][0] == '!')		return dyn_event_release(argc, argv, NULL); 	mutex_lock(&dyn_event_ops_mutex);	list_for_each_entry(ops, &dyn_event_ops_list, list) {		ret = ops->create(argc, (const char **)argv);		if (!ret || ret != -ECANCELED)			break;	}	mutex_unlock(&dyn_event_ops_mutex);	if (ret == -ECANCELED)		ret = -EINVAL; 	return ret;} /* Protected by event_mutex */LIST_HEAD(dyn_event_list); void *dyn_event_seq_start(struct seq_file *m, loff_t *pos){	mutex_lock(&event_mutex);	return seq_list_start(&dyn_event_list, *pos);} void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos){	return seq_list_next(v, &dyn_event_list, pos);} void dyn_event_seq_stop(struct seq_file *m, void *v){	mutex_unlock(&event_mutex);} static int dyn_event_seq_show(struct seq_file *m, void *v){	struct dyn_event *ev = v; 	if (ev && ev->ops)		return ev->ops->show(m, ev); 	return 0;} static const struct seq_operations dyn_event_seq_op = {	.start	= dyn_event_seq_start,	.next	= dyn_event_seq_next,	.stop	= dyn_event_seq_stop,	.show	= dyn_event_seq_show}; /* * dyn_events_release_all - Release all specific events * @type:	the dyn_event_operations * which filters releasing events * * This releases all events which ->ops matches @type. If @type is NULL, * all events are released. * Return -EBUSY if any of them are in use, and return other errors when * it failed to free the given event. Except for -EBUSY, event releasing * process will be aborted at that point and there may be some other * releasable events on the list. */int dyn_events_release_all(struct dyn_event_operations *type){	struct dyn_event *ev, *tmp;	int ret = 0; 	mutex_lock(&event_mutex);	for_each_dyn_event(ev) {		if (type && ev->ops != type)			continue;		if (ev->ops->is_busy(ev)) {			ret = -EBUSY;			goto out;		}	}	for_each_dyn_event_safe(ev, tmp) {		if (type && ev->ops != type)			continue;		ret = ev->ops->free(ev);		if (ret)			break;	}out:	mutex_unlock(&event_mutex); 	return ret;} static int dyn_event_open(struct inode *inode, struct file *file){	int ret; 	if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {		ret = dyn_events_release_all(NULL);		if (ret < 0)			return ret;	} 	return seq_open(file, &dyn_event_seq_op);} static ssize_t dyn_event_write(struct file *file, const char __user *buffer,				size_t count, loff_t *ppos){	return trace_parse_run_command(file, buffer, count, ppos,				       create_dyn_event);} static const struct file_operations dynamic_events_ops = {	.owner          = THIS_MODULE,	.open           = dyn_event_open,	.read           = seq_read,	.llseek         = seq_lseek,	.release        = seq_release,	.write		= dyn_event_write,}; /* Make a tracefs interface for controlling dynamic events */static __init int init_dynamic_event(void){	struct dentry *d_tracer;	struct dentry *entry; 	d_tracer = tracing_init_dentry();	if (IS_ERR(d_tracer))		return 0; 	entry = tracefs_create_file("dynamic_events", 0644, d_tracer,				    NULL, &dynamic_events_ops); 	/* Event list interface */	if (!entry)		pr_warn("Could not create tracefs 'dynamic_events' entry\n"); 	return 0;}fs_initcall(init_dynamic_event);