----- Original Message -----
> From: "Frederic Weisbecker" <[email protected]>
> To: "LKML" <[email protected]>
> Cc: "Frederic Weisbecker" <[email protected]>, "Andrew Morton"
> <[email protected]>, "Ingo Molnar"
> <[email protected]>, "Mathieu Desnoyers" <[email protected]>,
> "Oleg Nesterov" <[email protected]>, "Steven
> Rostedt" <[email protected]>
> Sent: Wednesday, April 9, 2014 12:11:19 PM
> Subject: [PATCH 2/5] tracepoint: Convert process iteration to use
> for_each_process_thread()
>
> do_each_thread/while_each_thread iterators are deprecated by
> for_each_thread/for_each_process_thread() APIs.
>
> Lets convert the callers in the tracepoint code. The ultimate
> goal is to remove the struct task_struct::thread_group field and
> the corresponding do_each_thread/while_each_thread iterators that are
> RCU unsafe.
>
> Cc: Andrew Morton <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Mathieu Desnoyers <[email protected]>
> Cc: Oleg Nesterov <[email protected]>
> Cc: Steven Rostedt <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> ---
> kernel/tracepoint.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
> index fb0a38a..00a7e8b 100644
> --- a/kernel/tracepoint.c
> +++ b/kernel/tracepoint.c
> @@ -561,15 +561,15 @@ static int sys_tracepoint_refcount;
> void syscall_regfunc(void)
> {
> unsigned long flags;
> - struct task_struct *g, *t;
> + struct task_struct *p, *t;
>
> if (!sys_tracepoint_refcount) {
> read_lock_irqsave(&tasklist_lock, flags);
> - do_each_thread(g, t) {
> + for_each_process_thread(p, t) {
What are the locking rules for for_each_process_thread() ?
Is it required to hold RCU read-side lock ? (it's not the case here)
Is tasklist_lock read-side lock sufficient ?
A quick glance at those for_each iterator defines in sched.h was not
helpful in finding this information.
Thanks,
Mathieu
> /* Skip kernel threads. */
> if (t->mm)
> set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
> - } while_each_thread(g, t);
> + }
> read_unlock_irqrestore(&tasklist_lock, flags);
> }
> sys_tracepoint_refcount++;
> @@ -578,14 +578,14 @@ void syscall_regfunc(void)
> void syscall_unregfunc(void)
> {
> unsigned long flags;
> - struct task_struct *g, *t;
> + struct task_struct *p, *t;
>
> sys_tracepoint_refcount--;
> if (!sys_tracepoint_refcount) {
> read_lock_irqsave(&tasklist_lock, flags);
> - do_each_thread(g, t) {
> + for_each_process_thread(p, t) {
> clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
> - } while_each_thread(g, t);
> + }
> read_unlock_irqrestore(&tasklist_lock, flags);
> }
> }
> --
> 1.8.3.1
>
>
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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