On Thu, 2014-03-13 at 18:37 +0000, Will Deacon wrote:
No, return_hooker is consistent with all the other archs. Hey, it's a rugby position! Note, which I was when I played. ;-)
Hehe, in which case your children will be able to execute that line of ftrace!
My kids already know I was :-)
trace.func = self_addr;in kernel/ftrace/ftrace.c there's an smb_wmb() between setting up tracing_graph_pause and setting the ret_stack with a comment saying:
/* Make sure the tasks see the -1 first: */Why don't we have a corresponding read-barrier here?
The corresponding rmb is in kernel/trace/trace_function_graph ftrace_push_return_trace().
Okey doke then, I guess we don't really care about tracing_graph_pause getting out-of-sync with curr_ret_stack.
Yep, the tracing_graph_pause is more to prevent crazy stuff happening when an interrupt comes in. So it is just local cpu context, and doesn't have issues with other CPUS. If it takes a bit for the task to see it go to zero, the worse thing is that you might miss a few tracing functions until that gets synced. Which will probably happen by the time tracing is fully activated anyway.
-- Steve