| // 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); |