[PATCH 2/2] tracing: syscall_regfunc() should not skip kernelthreads

From: Oleg Nesterov
Date: Sun Mar 17 2013 - 14:30:47 EST

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.

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 <oleg@xxxxxxxxxx>
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) {
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);

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