On Tue, Sep 10, 2019 at 05:28:04AM -0400, Steven Rostedt wrote:
> On Tue, 10 Sep 2019 08:33:23 +0800
> Changbin Du <changbin...@gmail.com> wrote:
>
> > >
> > > bool ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip, bool
> > > empty_result)
> > > {
> > > if (ftrace_hash_empty(hash))
> > > return empty_result;
> > >
> > > return __ftrace_lookup_ip(hash, ip);
> > > }
> > >
> > We must add another similar function since ftrace_lookup_ip() returns a
> > pointer.
> >
> > bool ftrace_contains_ip(struct ftrace_hash *hash, unsigned long ip,
> > bool empty_result)
> > {
> > if (ftrace_hash_empty(hash))
> > return empty_result;
> >
> > return !!__ftrace_lookup_ip(hash, ip);
> > }
> >
> > But after this, it's a little overkill I think. It is not much simpler than
> > before.
> > Do you still want this then?
> >
> >
>
> Or...
>
> static struct ftrace_func_entry empty_func_entry;
> #define EMPTY_FUNC_ENTRY = &empty_func_entry;
>
> [..]
> * @empty_result: return NULL if false or EMPTY_FUNC_ENTRY on true
> [..]
> * @empty_result should be false, unless this is used for testing if the ip
> * exists in the hash, and an empty hash should be considered true.
> * This is useful when the empty hash is considered to contain all addresses.
> [..]
> struct ftrace_func_entry *
> ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip, bool
> empty_result)
> {
> if (ftrace_hash_empty(hash))
> return empty_result ? EMPTY_FUNC_ENTRY : NULL;
>
> return __ftrace_lookup_ip(hash, ip);
> }
>
> But looking at this more, I'm going back to not touching the code in
> this location, because __ftrace_lookup_ip() is static, where as
> ftrace_lookup_ip() is not, and this is in a very fast path, and I
> rather keep it open coded.
>
> Lets just drop the first hunk of your patch. The second hunk is fine.
>
Sure, I will send a update short later. Thanks for your suggestions.
>
> -- Steve
--
Cheers,
Changbin Du
