diff options
Diffstat (limited to 'samples/trace_events/trace-events-sample.c')
| -rw-r--r-- | samples/trace_events/trace-events-sample.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/samples/trace_events/trace-events-sample.c b/samples/trace_events/trace-events-sample.c new file mode 100644 index 000000000..ca5d98c36 --- /dev/null +++ b/samples/trace_events/trace-events-sample.c @@ -0,0 +1,193 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/module.h> +#include <linux/kthread.h> + +/* + * Any file that uses trace points, must include the header. + * But only one file, must include the header by defining + * CREATE_TRACE_POINTS first. This will make the C code that + * creates the handles for the trace points. + */ +#define CREATE_TRACE_POINTS +#include "trace-events-sample.h" + +static const char *random_strings[] = { + "Mother Goose", + "Snoopy", + "Gandalf", + "Frodo", + "One ring to rule them all" +}; + +static void do_simple_thread_func(int cnt, const char *fmt, ...) +{ + unsigned long bitmask[1] = {0xdeadbeefUL}; + va_list va; + int array[6]; + int len = cnt % 5; + int i; + + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(HZ); + + for (i = 0; i < len; i++) + array[i] = i + 1; + array[i] = 0; + + va_start(va, fmt); + + /* Silly tracepoints */ + trace_foo_bar("hello", cnt, array, random_strings[len], + current->cpus_ptr, fmt, &va); + + va_end(va); + + trace_foo_with_template_simple("HELLO", cnt); + + trace_foo_bar_with_cond("Some times print", cnt); + + trace_foo_with_template_cond("prints other times", cnt); + + trace_foo_with_template_print("I have to be different", cnt); + + trace_foo_rel_loc("Hello __rel_loc", cnt, bitmask, current->cpus_ptr); +} + +static void simple_thread_func(int cnt) +{ + do_simple_thread_func(cnt, "iter=%d", cnt); +} + +static int simple_thread(void *arg) +{ + int cnt = 0; + + while (!kthread_should_stop()) + simple_thread_func(cnt++); + + return 0; +} + +static struct task_struct *simple_tsk; +static struct task_struct *simple_tsk_fn; + +static void simple_thread_func_fn(int cnt) +{ + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(HZ); + + /* More silly tracepoints */ + trace_foo_bar_with_fn("Look at me", cnt); + trace_foo_with_template_fn("Look at me too", cnt); +} + +static int simple_thread_fn(void *arg) +{ + int cnt = 0; + + while (!kthread_should_stop()) + simple_thread_func_fn(cnt++); + + return 0; +} + +static DEFINE_MUTEX(thread_mutex); +static int simple_thread_cnt; + +static struct foo_timer_data *foo_timer_data; + +static void sample_timer_cb(struct timer_list *t) +{ + struct foo_timer_data *data = container_of(t, struct foo_timer_data, timer); + + get_cpu(); + trace_foo_timer_fn(data); + (*this_cpu_ptr(data->counter))++; + put_cpu(); + + mod_timer(t, jiffies + HZ); +} + +int foo_bar_reg(void) +{ + mutex_lock(&thread_mutex); + if (simple_thread_cnt++) + goto out; + + pr_info("Starting thread for foo_bar_fn\n"); + /* + * We shouldn't be able to start a trace when the module is + * unloading (there's other locks to prevent that). But + * for consistency sake, we still take the thread_mutex. + */ + simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn"); + if (IS_ERR_OR_NULL(simple_tsk_fn)) { + pr_err("Failed to create simple_thread_fn\n"); + simple_tsk_fn = NULL; + } + out: + mutex_unlock(&thread_mutex); + return 0; +} + +void foo_bar_unreg(void) +{ + mutex_lock(&thread_mutex); + if (--simple_thread_cnt) + goto out; + + pr_info("Killing thread for foo_bar_fn\n"); + if (simple_tsk_fn) + kthread_stop(simple_tsk_fn); + simple_tsk_fn = NULL; + out: + mutex_unlock(&thread_mutex); +} + +static int __init trace_event_init(void) +{ + foo_timer_data = kzalloc_obj(*foo_timer_data, GFP_KERNEL); + if (!foo_timer_data) + return -ENOMEM; + + foo_timer_data->name = "sample_timer_counter"; + foo_timer_data->counter = alloc_percpu(int); + if (!foo_timer_data->counter) { + kfree(foo_timer_data); + return -ENOMEM; + } + + timer_setup(&foo_timer_data->timer, sample_timer_cb, 0); + mod_timer(&foo_timer_data->timer, jiffies + HZ); + + simple_tsk = kthread_run(simple_thread, NULL, "event-sample"); + if (IS_ERR(simple_tsk)) { + timer_shutdown_sync(&foo_timer_data->timer); + free_percpu(foo_timer_data->counter); + kfree(foo_timer_data); + return PTR_ERR(simple_tsk); + } + + return 0; +} + +static void __exit trace_event_exit(void) +{ + kthread_stop(simple_tsk); + mutex_lock(&thread_mutex); + if (simple_tsk_fn) + kthread_stop(simple_tsk_fn); + simple_tsk_fn = NULL; + mutex_unlock(&thread_mutex); + + timer_shutdown_sync(&foo_timer_data->timer); + free_percpu(foo_timer_data->counter); + kfree(foo_timer_data); +} + +module_init(trace_event_init); +module_exit(trace_event_exit); + +MODULE_AUTHOR("Steven Rostedt"); +MODULE_DESCRIPTION("trace-events-sample"); +MODULE_LICENSE("GPL"); |