(2013/07/30 1:40), Tom Zanussi wrote: > The original SOFT_DISABLE patches didn't add support for soft disable > of syscall events; this adds it and paves the way for future patches > allowing triggers to be added to syscall events, since triggers are > built on top of SOFT_DISABLE. > > Add an array of ftrace_event_file pointers indexed by syscall number > to the trace array and remove the existing enabled bitmaps, which as a > result are now redundant. The ftrace_event_file structs in turn > contain the soft disable flags we need for per-syscall soft disable > accounting; later patches add additional 'trigger' flags and > per-syscall triggers and filters.
At this point, this looks OK for me. Note, this could be racy after introducing event-trigger which makes some other event soft-disabled. Currently only function tracer makes soft-disabled and it works only on the default instance. However introducing trigger interface, there can be events in soft-mode, and ftrace_event_enable_disable(file, set = 0) to those events always fail. > > Signed-off-by: Tom Zanussi <[email protected]> > --- > kernel/trace/trace.h | 4 ++-- > kernel/trace/trace_syscalls.c | 34 ++++++++++++++++++++++++++++------ > 2 files changed, 30 insertions(+), 8 deletions(-) > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index afaae41..3dd994e8 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -192,8 +192,8 @@ struct trace_array { > #ifdef CONFIG_FTRACE_SYSCALLS > int sys_refcount_enter; > int sys_refcount_exit; > - DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls); > - DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls); > + struct ftrace_event_file *enter_syscall_files[NR_syscalls]; > + struct ftrace_event_file *exit_syscall_files[NR_syscalls]; > #endif > int stop_count; > int clock_id; > diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c > index 8fd0365..294cfe8 100644 > --- a/kernel/trace/trace_syscalls.c > +++ b/kernel/trace/trace_syscalls.c > @@ -302,6 +302,7 @@ static int __init syscall_exit_define_fields(struct > ftrace_event_call *call) > static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id) > { > struct trace_array *tr = data; > + struct ftrace_event_file *ftrace_file; > struct syscall_trace_enter *entry; > struct syscall_metadata *sys_data; > struct ring_buffer_event *event; > @@ -314,7 +315,12 @@ static void ftrace_syscall_enter(void *data, struct > pt_regs *regs, long id) > syscall_nr = trace_get_syscall_nr(current, regs); > if (syscall_nr < 0) > return; > - if (!test_bit(syscall_nr, tr->enabled_enter_syscalls)) > + OK, since all tracepoint handlers run under rcu_read_lock, we can safely use rcu_dereference_raw() here. :) To avoid misread, I think you'd better add a comment here. > + ftrace_file = rcu_dereference_raw(tr->enter_syscall_files[syscall_nr]); > + if (!ftrace_file) > + return; > + > + if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags)) > return; > Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: [email protected] -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
