From 3cccbf08e333d32a63d7160b9b73fb330a559780 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 13 Apr 2014 20:59:38 +0200 Subject: [PATCH] tracing: syscall_regfunc() should not skip kernel threads 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 Change-Id: Ic61b8b2d4f2cec27d7cf681a8b39020ed65e2e43 Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt --- kernel/tracepoint.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index 78762de1fc1f..918563cc89f0 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -753,9 +753,7 @@ 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); }