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tracing: Check all tasks on each CPU when filtering pids

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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: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2015-10-21 15:27:36 -04:00 committed by Steven Rostedt
parent 3fdaf80f4a
commit 8ca532ad2b
1 changed files with 22 additions and 0 deletions
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22
kernel/trace/trace_events.c
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@ -1549,6 +1549,22 @@ static int max_pids(struct trace_pid_list *pid_list)
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
ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
@ -1711,6 +1727,12 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
tr, INT_MAX);
register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_post,
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);