diff options
| -rw-r--r-- | include/linux/ftrace_event.h | 20 | ||||
| -rw-r--r-- | include/trace/ftrace.h | 8 | ||||
| -rw-r--r-- | kernel/trace/trace_events.c | 75 |
3 files changed, 84 insertions, 19 deletions
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index 4cb6cd8338a4..4e28b011e63b 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -251,16 +251,23 @@ struct ftrace_subsystem_dir; enum { FTRACE_EVENT_FL_ENABLED_BIT, FTRACE_EVENT_FL_RECORDED_CMD_BIT, + FTRACE_EVENT_FL_SOFT_MODE_BIT, + FTRACE_EVENT_FL_SOFT_DISABLED_BIT, }; /* * Ftrace event file flags: * ENABLED - The event is enabled * RECORDED_CMD - The comms should be recorded at sched_switch + * SOFT_MODE - The event is enabled/disabled by SOFT_DISABLED + * SOFT_DISABLED - When set, do not trace the event (even though its + * tracepoint may be enabled) */ enum { FTRACE_EVENT_FL_ENABLED = (1 << FTRACE_EVENT_FL_ENABLED_BIT), FTRACE_EVENT_FL_RECORDED_CMD = (1 << FTRACE_EVENT_FL_RECORDED_CMD_BIT), + FTRACE_EVENT_FL_SOFT_MODE = (1 << FTRACE_EVENT_FL_SOFT_MODE_BIT), + FTRACE_EVENT_FL_SOFT_DISABLED = (1 << FTRACE_EVENT_FL_SOFT_DISABLED_BIT), }; struct ftrace_event_file { @@ -274,17 +281,18 @@ struct ftrace_event_file { * 32 bit flags: * bit 0: enabled * bit 1: enabled cmd record + * bit 2: enable/disable with the soft disable bit + * bit 3: soft disabled * - * Changes to flags must hold the event_mutex. - * - * Note: Reads of flags do not hold the event_mutex since - * they occur in critical sections. But the way flags + * Note: The bits must be set atomically to prevent races + * from other writers. Reads of flags do not need to be in + * sync as they occur in critical sections. But the way flags * is currently used, these changes do not affect the code * except that when a change is made, it may have a slight * delay in propagating the changes to other CPUs due to - * caching and such. + * caching and such. Which is mostly OK ;-) */ - unsigned int flags; + unsigned long flags; }; #define __TRACE_EVENT_FLAGS(name, value) \ diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h index bbf09c2021b9..4bda044e6c77 100644 --- a/include/trace/ftrace.h +++ b/include/trace/ftrace.h @@ -413,6 +413,10 @@ static inline notrace int ftrace_get_offsets_##call( \ * int __data_size; * int pc; * + * if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, + * &ftrace_file->flags)) + * return; + * * local_save_flags(irq_flags); * pc = preempt_count(); * @@ -518,6 +522,10 @@ ftrace_raw_event_##call(void *__data, proto) \ int __data_size; \ int pc; \ \ + if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, \ + &ftrace_file->flags)) \ + return; \ + \ local_save_flags(irq_flags); \ pc = preempt_count(); \ \ diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 38b54c5edeb9..106640b0df4a 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -205,37 +205,77 @@ void trace_event_enable_cmd_record(bool enable) if (enable) { tracing_start_cmdline_record(); - file->flags |= FTRACE_EVENT_FL_RECORDED_CMD; + set_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags); } else { tracing_stop_cmdline_record(); - file->flags &= ~FTRACE_EVENT_FL_RECORDED_CMD; + clear_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags); } } while_for_each_event_file(); mutex_unlock(&event_mutex); } -static int ftrace_event_enable_disable(struct ftrace_event_file *file, - int enable) +static int __ftrace_event_enable_disable(struct ftrace_event_file *file, + int enable, int soft_disable) { struct ftrace_event_call *call = file->event_call; int ret = 0; + int disable; switch (enable) { case 0: - if (file->flags & FTRACE_EVENT_FL_ENABLED) { - file->flags &= ~FTRACE_EVENT_FL_ENABLED; + /* + * When soft_disable is set and enable is cleared, we want + * to clear the SOFT_DISABLED flag but leave the event in the + * state that it was. That is, if the event was enabled and + * SOFT_DISABLED isn't set, then do nothing. But if SOFT_DISABLED + * is set we do not want the event to be enabled before we + * clear the bit. + * + * When soft_disable is not set but the SOFT_MODE flag is, + * we do nothing. Do not disable the tracepoint, otherwise + * "soft enable"s (clearing the SOFT_DISABLED bit) wont work. + */ + if (soft_disable) { + disable = file->flags & FTRACE_EVENT_FL_SOFT_DISABLED; + clear_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags); + } else + disable = !(file->flags & FTRACE_EVENT_FL_SOFT_MODE); + + if (disable && (file->flags & FTRACE_EVENT_FL_ENABLED)) { + clear_bit(FTRACE_EVENT_FL_ENABLED_BIT, &file->flags); if (file->flags & FTRACE_EVENT_FL_RECORDED_CMD) { tracing_stop_cmdline_record(); - file->flags &= ~FTRACE_EVENT_FL_RECORDED_CMD; + clear_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags); } call->class->reg(call, TRACE_REG_UNREGISTER, file); } + /* If in SOFT_MODE, just set the SOFT_DISABLE_BIT */ + if (file->flags & FTRACE_EVENT_FL_SOFT_MODE) + set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags); break; case 1: + /* + * When soft_disable is set and enable is set, we want to + * register the tracepoint for the event, but leave the event + * as is. That means, if the event was already enabled, we do + * nothing (but set SOFT_MODE). If the event is disabled, we + * set SOFT_DISABLED before enabling the event tracepoint, so + * it still seems to be disabled. + */ + if (!soft_disable) + clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags); + else + set_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags); + if (!(file->flags & FTRACE_EVENT_FL_ENABLED)) { + + /* Keep the event disabled, when going to SOFT_MODE. */ + if (soft_disable) + set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags); + if (trace_flags & TRACE_ITER_RECORD_CMD) { tracing_start_cmdline_record(); - file->flags |= FTRACE_EVENT_FL_RECORDED_CMD; + set_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags); } ret = call->class->reg(call, TRACE_REG_REGISTER, file); if (ret) { @@ -244,7 +284,7 @@ static int ftrace_event_enable_disable(struct ftrace_event_file *file, "%s\n", call->name); break; } - file->flags |= FTRACE_EVENT_FL_ENABLED; + set_bit(FTRACE_EVENT_FL_ENABLED_BIT, &file->flags); /* WAS_ENABLED gets set but never cleared. */ call->flags |= TRACE_EVENT_FL_WAS_ENABLED; @@ -255,6 +295,12 @@ static int ftrace_event_enable_disable(struct ftrace_event_file *file, return ret; } +static int ftrace_event_enable_disable(struct ftrace_event_file *file, + int enable) +{ + return __ftrace_event_enable_disable(file, enable, 0); +} + static void ftrace_clear_events(struct trace_array *tr) { struct ftrace_event_file *file; @@ -547,12 +593,15 @@ event_enable_read(struct file *filp, char __user *ubuf, size_t cnt, struct ftrace_event_file *file = filp->private_data; char *buf; - if (file->flags & FTRACE_EVENT_FL_ENABLED) - buf = "1\n"; - else + if (file->flags & FTRACE_EVENT_FL_ENABLED) { + if (file->flags & FTRACE_EVENT_FL_SOFT_DISABLED) + buf = "0*\n"; + else + buf = "1\n"; + } else buf = "0\n"; - return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2); + return simple_read_from_buffer(ubuf, cnt, ppos, buf, strlen(buf)); } static ssize_t |