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.
-- Steve
