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Commit 8ca532ad authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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tracing: Check all tasks on each CPU when filtering pids 



My tests found that if a task is running but not filtered when set_event_pid
is modified, then it can still be traced.

Call on_each_cpu() to check if the current running task should be filtered
and update the per cpu flags of tr->data appropriately.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 3fdaf80f

kernel/trace/trace_events.c

+22 −0
Original line number Original line Diff line number Diff line
@@ -1549,6 +1549,22 @@ static int max_pids(struct trace_pid_list *pid_list) 
	return (PAGE_SIZE << pid_list->order) / sizeof(pid_t);

	return (PAGE_SIZE << pid_list->order) / sizeof(pid_t);

}

}





static void ignore_task_cpu(void *data)

{

	struct trace_array *tr = data;

	struct trace_pid_list *pid_list;



	/*

	 * This function is called by on_each_cpu() while the

	 * event_mutex is held.

	 */

	pid_list = rcu_dereference_protected(tr->filtered_pids,

					     mutex_is_locked(&event_mutex));



	this_cpu_write(tr->trace_buffer.data->ignore_pid,

		       check_ignore_pid(pid_list, current));

}



static ssize_t

static ssize_t

ftrace_event_pid_write(struct file *filp, const char __user *ubuf,

ftrace_event_pid_write(struct file *filp, const char __user *ubuf,

		       size_t cnt, loff_t *ppos)

		       size_t cnt, loff_t *ppos)
@@ -1711,6 +1727,12 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf, 
						 tr, INT_MAX);

						 tr, INT_MAX);

		register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_post,

		register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_post,

						 tr, 0);

						 tr, 0);



		/*

		 * Ignoring of pids is done at task switch. But we have to

		 * check for those tasks that are currently running.

		 */

		on_each_cpu(ignore_task_cpu, tr, 1);

	}

	}





	mutex_unlock(&event_mutex);

	mutex_unlock(&event_mutex);