diff options
Diffstat (limited to 'kernel/trace/trace_dynevent.c')
| -rw-r--r-- | kernel/trace/trace_dynevent.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c new file mode 100644 index 000000000000..f17a887abb66 --- /dev/null +++ b/kernel/trace/trace_dynevent.c @@ -0,0 +1,210 @@ +// 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][1] != ':') + return -EINVAL; + + event = &argv[0][2]; + 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; + + if (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); |