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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2014-05-07 23:06:14 +0400
committerSteven Rostedt <rostedt@goodmis.org>2014-05-14 19:37:27 +0400
commit19eab4a472cfe4a3ae51cff1711d795e3f9bb564 (patch)
treea264bc0d172af2f9c425ba676afd47cce46ecb3d /kernel/trace
parent66209a5bd4825e8890bfb65d48efa8a47c647fea (diff)
downloadlinux-19eab4a472cfe4a3ae51cff1711d795e3f9bb564.tar.xz
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 <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/ftrace.c7
1 files changed, 7 insertions, 0 deletions
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;