8cf868affd
Some tracepoints have a registration function that gets enabled when the tracepoint is enabled. There may be cases that the registraction function must fail (for example, can't allocate enough memory). In this case, the tracepoint should also fail to register, otherwise the user would not know why the tracepoint is not working. Cc: David Howells <dhowells@redhat.com> Cc: Seiji Aguchi <seiji.aguchi@hds.com> Cc: Anton Blanchard <anton@samba.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
132 lines
2.8 KiB
C
132 lines
2.8 KiB
C
#include <linux/module.h>
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#include <linux/kthread.h>
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/*
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* Any file that uses trace points, must include the header.
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* But only one file, must include the header by defining
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* CREATE_TRACE_POINTS first. This will make the C code that
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* creates the handles for the trace points.
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*/
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#define CREATE_TRACE_POINTS
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#include "trace-events-sample.h"
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static const char *random_strings[] = {
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"Mother Goose",
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"Snoopy",
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"Gandalf",
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"Frodo",
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"One ring to rule them all"
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};
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static void simple_thread_func(int cnt)
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{
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int array[6];
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int len = cnt % 5;
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int i;
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set_current_state(TASK_INTERRUPTIBLE);
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schedule_timeout(HZ);
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for (i = 0; i < len; i++)
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array[i] = i + 1;
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array[i] = 0;
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/* Silly tracepoints */
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trace_foo_bar("hello", cnt, array, random_strings[len],
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tsk_cpus_allowed(current));
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trace_foo_with_template_simple("HELLO", cnt);
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trace_foo_bar_with_cond("Some times print", cnt);
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trace_foo_with_template_cond("prints other times", cnt);
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trace_foo_with_template_print("I have to be different", cnt);
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}
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static int simple_thread(void *arg)
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{
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int cnt = 0;
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while (!kthread_should_stop())
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simple_thread_func(cnt++);
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return 0;
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}
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static struct task_struct *simple_tsk;
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static struct task_struct *simple_tsk_fn;
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static void simple_thread_func_fn(int cnt)
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{
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set_current_state(TASK_INTERRUPTIBLE);
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schedule_timeout(HZ);
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/* More silly tracepoints */
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trace_foo_bar_with_fn("Look at me", cnt);
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trace_foo_with_template_fn("Look at me too", cnt);
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}
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static int simple_thread_fn(void *arg)
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{
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int cnt = 0;
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while (!kthread_should_stop())
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simple_thread_func_fn(cnt++);
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return 0;
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}
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static DEFINE_MUTEX(thread_mutex);
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int foo_bar_reg(void)
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{
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pr_info("Starting thread for foo_bar_fn\n");
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/*
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* We shouldn't be able to start a trace when the module is
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* unloading (there's other locks to prevent that). But
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* for consistency sake, we still take the thread_mutex.
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*/
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mutex_lock(&thread_mutex);
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simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");
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mutex_unlock(&thread_mutex);
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return 0;
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}
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void foo_bar_unreg(void)
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{
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pr_info("Killing thread for foo_bar_fn\n");
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/* protect against module unloading */
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mutex_lock(&thread_mutex);
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if (simple_tsk_fn)
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kthread_stop(simple_tsk_fn);
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simple_tsk_fn = NULL;
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mutex_unlock(&thread_mutex);
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}
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static int __init trace_event_init(void)
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{
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simple_tsk = kthread_run(simple_thread, NULL, "event-sample");
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if (IS_ERR(simple_tsk))
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return -1;
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return 0;
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}
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static void __exit trace_event_exit(void)
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{
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kthread_stop(simple_tsk);
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mutex_lock(&thread_mutex);
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if (simple_tsk_fn)
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kthread_stop(simple_tsk_fn);
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simple_tsk_fn = NULL;
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mutex_unlock(&thread_mutex);
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}
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module_init(trace_event_init);
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module_exit(trace_event_exit);
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MODULE_AUTHOR("Steven Rostedt");
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MODULE_DESCRIPTION("trace-events-sample");
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MODULE_LICENSE("GPL");
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