Commit 19eab4a4 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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ftrace: Write in missing comment from a very old commit

Back in 2011 Commit ed926f9b

 "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: default avatarSteven Rostedt <>
parent 66209a5b
......@@ -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;
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