Messages in this thread Patch in this message | | | Date | Fri, 20 Jun 2014 06:45:21 -0400 | From | Steven Rostedt <> | Subject | [for-next][PATCH v2 3/3] tracing: syscall_regfunc() should not skip kernel threads |
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From: Oleg Nesterov <oleg@redhat.com>
syscall_regfunc() ignores the kernel threads because "it has no effect", see cc3b13c1 "Don't trace kernel thread syscalls" which added this check.
However, this means that a user-space task spawned by call_usermodehelper() will run without TIF_SYSCALL_TRACEPOINT if sys_tracepoint_refcount != 0.
Remove this check. The unnecessary report from ret_from_fork path mentioned by cc3b13c1 is no longer possible, see See commit fb45550d76bb5 "make sure that kernel_thread() callbacks call do_exit() themselves".
A kernel_thread() callback can only return and take the int_ret_from_sys_call path after do_execve() succeeds, otherwise the kernel will crash. But in this case it is no longer a kernel thread and thus is needs TIF_SYSCALL_TRACEPOINT.
Link: http://lkml.kernel.org/p/20140413185938.GD20668@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> --- kernel/tracepoint.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index 9cf12640de5a..3490407dc7b7 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -497,9 +497,7 @@ void syscall_regfunc(void) if (!sys_tracepoint_refcount) { read_lock(&tasklist_lock); for_each_process_thread(p, 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); } read_unlock(&tasklist_lock); } -- 2.0.0
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