[PATCH RESEND 2/2] tracing: syscall_regfunc() should not skip kernel threads

From: Oleg Nesterov
Date: Wed Apr 09 2014 - 13:06:23 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) {
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);
}
--
1.5.5.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/