On Wed, 9 Apr 2014 19:06:16 +0200
Oleg Nesterov <o...@redhat.com> wrote:
> syscall_regfunc() ignores the kernel thread because "it has
> no effect", see cc3b13c1 "Don't trace kernel thread syscalls".
>
> However, this means that a user-space task spawned by
> call_usermodehelper() won't report the system calls if
> kernel_execve() is called when sys_tracepoint_refcount != 0.
What about doing the set there? That is, we could add a check in the
call_userspacehelper() just before it does the do_execve, that if
sys_tracepoint_refcount is set, we set the TIF flag.
-- Steve
>
> Remove this check. Hopefully the unnecessary report from
> ret_from_fork path mentioned by cc3b13c1 is fine. In fact
> "this is the only case" is not true. Say, kernel_execve()
> itself does "int 80" on X86_32. Hopefully fine too.
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> ---
> kernel/tracepoint.c | 4 +---
> 1 files changed, 1 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
> index a16754b..4e1e4ca 100644
> --- a/kernel/tracepoint.c
> +++ b/kernel/tracepoint.c
> @@ -737,9 +737,7 @@ void syscall_regfunc(void)
> if (!sys_tracepoint_refcount) {
> read_lock(&tasklist_lock);
> do_each_thread(g, t) {
> - /* Skip kernel threads. */
> - if (!(t->flags & PF_KTHREAD))
> - set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
> + set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
> } while_each_thread(g, t);
> read_unlock(&tasklist_lock);
> }
--
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