From 19eab4a472cfe4a3ae51cff1711d795e3f9bb564 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Wed, 7 May 2014 15:06:14 -0400 Subject: [PATCH] ftrace: Write in missing comment from a very old commit Back in 2011 Commit ed926f9b35cda "ftrace: Use counters to enable functions to trace" changed the way ftrace accounts for enabled and disabled traced functions. There was a comment started as: /* * */ But never finished. Well, that's rather useless. I probably forgot to save the file before committing it. And it passed review from all this time. Anyway, better late than never. I updated the comment to express what is happening in that somewhat complex code. Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 2c99d1f7caf1..61f39f8b62e1 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1552,7 +1552,14 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops, in_other_hash = !!ftrace_lookup_ip(other_hash, rec->ip); /* + * If filter_hash is set, we want to match all functions + * that are in the hash but not in the other hash. * + * If filter_hash is not set, then we are decrementing. + * That means we match anything that is in the hash + * and also in the other_hash. That is, we need to turn + * off functions in the other hash because they are disabled + * by this hash. */ if (filter_hash && in_hash && !in_other_hash) match = 1;