#include #include /* * 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 simple_thread_func(int cnt) { 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; /* Silly tracepoints */ trace_foo_bar("hello", cnt, array, random_strings[len], tsk_cpus_allowed(current)); 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); } 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); int foo_bar_reg(void) { 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. */ mutex_lock(&thread_mutex); simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn"); mutex_unlock(&thread_mutex); return 0; } void foo_bar_unreg(void) { pr_info("Killing thread for foo_bar_fn\n"); /* protect against module unloading */ mutex_lock(&thread_mutex); if (simple_tsk_fn) kthread_stop(simple_tsk_fn); simple_tsk_fn = NULL; mutex_unlock(&thread_mutex); } static int __init trace_event_init(void) { simple_tsk = kthread_run(simple_thread, NULL, "event-sample"); if (IS_ERR(simple_tsk)) return -1; 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); } module_init(trace_event_init); module_exit(trace_event_exit); MODULE_AUTHOR("Steven Rostedt"); MODULE_DESCRIPTION("trace-events-sample"); MODULE_LICENSE("GPL"); private-remove'/>
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authorLinus Torvalds <torvalds@linux-foundation.org>2016-10-19 09:11:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-19 09:11:24 -0700
commit8835ca59dac2bc1e0136791abf3ccd51588803ce (patch)
tree29baa574daa8ea326ac07ba43a21e23d7a792fc0
parent63ae602cea637ee4a6490d940c0da5d78bd0bbe0 (diff)
printk: suppress empty continuation lines
We have a fairly common pattern where you print several things as continuations on one single line in a loop, and then at the end you do printk(KERN_CONT "\n"); to flush the buffered output. But if the output was flushed by something else (concurrent printk activity, or just system logging), we don't want that final flushing to just print an empty line. So just suppress empty continuation lines when they couldn't be merged into the line they are a continuation of. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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