Steven Rostedt <[EMAIL PROTECTED]> writes:
> From: Steven Rostedt <[EMAIL PROTECTED]>
>
> Impact: clean up
>
> Use the new task struct trace flags to determine if a process should be
> traced or not.
Looks reasonable.
> Note: this moves the searching of the pid to the slow path of setting
> the pid field. This needs to be converted to the pid name space.
>
> Signed-off-by: Steven Rostedt <[EMAIL PROTECTED]>
> ---
> kernel/trace/ftrace.c | 28 +++++++++++++++++++++++++---
> 1 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index b17a303..c5049f5 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -47,7 +47,7 @@
> int ftrace_enabled __read_mostly;
> static int last_ftrace_enabled;
>
> -/* ftrace_pid_trace >= 0 will only trace threads with this pid */
> +/* set when tracing only a pid */
> static int ftrace_pid_trace = -1;
>
> /* Quick disabling of function tracer. */
> @@ -90,7 +90,7 @@ static void ftrace_list_func(unsigned long ip, unsigned long
> parent_ip)
>
> static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip)
> {
> - if (current->pid != ftrace_pid_trace)
> + if (!test_tsk_trace_trace(current))
> return;
>
> ftrace_pid_function(ip, parent_ip);
> @@ -1714,11 +1714,33 @@ ftrace_pid_write(struct file *filp, const char __user
> *ubuf,
> ftrace_pid_trace = -1;
>
> } else {
> + struct task_struct *p;
> + int found = 0;
>
> if (ftrace_pid_trace == val)
> goto out;
>
> - ftrace_pid_trace = val;
> + /*
> + * Find the task that matches this pid.
> + * TODO: use pid namespaces instead.
> + */
> + rcu_read_lock();
> + for_each_process(p) {
> + if (p->pid == val) {
> + found = 1;
> + set_tsk_trace_trace(p);
> + } else if (test_tsk_trace_trace(p))
> + clear_tsk_trace_trace(p);
> + }
> + rcu_read_unlock();
Yes. This function you have just implemented inline is called find_pid.
It uses a hash lookup instead of an expensive walk trough all of the processes
in the system. So the code becomes something like:
do_each_pid_task(ftrace_pid_trace, PIDTYPE_PID, task) {
clear_tsk_trace_tace(p);
} while_each_pid_task(pid, PIDTYPE_PID, task);
put_pid(ftrace_pid_trace);
ftrace_pid_trace = find_get_vpid(val);
do_each_pid_task(ftrace_pid_trace, PIDTYPE_PID, task) {
set_tsk_trace_tace(p);
} while_each_pid_task(ftrace_pid_trace, PIDTYPE_PID, task);
if (!ftrace_pid_trace)
goto out;
The loops encompass both the test for validity, and handle the weird exec
case where the pid moves from one task to another.
Eric
_______________________________________________
Containers mailing list
[EMAIL PROTECTED]
https://lists.linux-foundation.org/mailman/listinfo/containers
_______________________________________________
Devel mailing list
[email protected]
https://openvz.org/mailman/listinfo/devel
