(2014/06/12 14:54), Namhyung Kim wrote: > On Thu, 12 Jun 2014 12:29:09 +0900, Masami Hiramatsu wrote: >> NO, ftrace_lookup_ip() returns NULL if the hash is empty, so adding >> !ftrace_hash_empty() is meaningless :) >> >> Actually, here I intended to have 3 meanings for the new/old_hash arguments, >> - If it is NULL, it hits all >> - If it is EMPTY_HASH, it hits nothing >> - If it has some entries, it hits those entries. >> >> And in ftrace.c(__ftrace_hash_rec_update), AFAICS, ops->filter_hash has only >> 2 meanings, >> - If it is EMPTY_HASH or NULL, it hits all >> - If it has some entries, it hits those entries. > > Then I found an unrelated issue during review. > > It seems that checking NULL other_hash for the 'all' case in > __ftrace_hash_rec_update() is not sufficient. It should check > EMPTY_HASH case too, but then it ends up removing the check at all since > it can be covered in ftrace_lookup_ip().
I guessed that was just for speeding up by skipping ftrace_lookup_ip(). (but I'm not sure how much it improves...) Reviewed-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> However, I'd like to ask Steven his Ack. Thank you, > > Thanks, > Namhyung > > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 13885590a184..8bd7aa69a479 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -1545,7 +1545,7 @@ static void __ftrace_hash_rec_update(struct ftrace_ops > *ops, > * Only the filter_hash affects all records. > * Update if the record is not in the notrace hash. > */ > - if (!other_hash || !ftrace_lookup_ip(other_hash, > rec->ip)) > + if (!ftrace_lookup_ip(other_hash, rec->ip)) > match = 1; > } else { > in_hash = !!ftrace_lookup_ip(hash, rec->ip); > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/