2019-09-09 09:42:36

by Changbin Du

Subject: [PATCH] ftrace: simplify ftrace hash lookup code

Function ftrace_lookup_ip() will check empty hash table. So we don't
need extra check outside.

Signed-off-by: Changbin Du <[email protected]>
---
kernel/trace/ftrace.c | 15 ++++-----------
kernel/trace/trace.h | 6 ------
2 files changed, 4 insertions(+), 17 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f9821a3374e9..85115deca667 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1461,10 +1461,8 @@ static bool hash_contains_ip(unsigned long ip,
* considered a match for the filter hash, but an empty
* notrace hash is considered not in the notrace hash.
*/
- return (ftrace_hash_empty(hash->filter_hash) ||
- __ftrace_lookup_ip(hash->filter_hash, ip)) &&
- (ftrace_hash_empty(hash->notrace_hash) ||
- !__ftrace_lookup_ip(hash->notrace_hash, ip));
+ return ftrace_lookup_ip(hash->filter_hash, ip) &&
+ !ftrace_lookup_ip(hash->notrace_hash, ip);
}

/*
@@ -2890,8 +2888,7 @@ ops_references_rec(struct ftrace_ops *ops, struct dyn_ftrace *rec)
return true;

/* The function must be in the filter */
- if (!ftrace_hash_empty(ops->func_hash->filter_hash) &&
- !__ftrace_lookup_ip(ops->func_hash->filter_hash, rec->ip))
+ if (!ftrace_lookup_ip(ops->func_hash->filter_hash, rec->ip))
return false;

/* If in notrace hash, we ignore it too */
@@ -6036,11 +6033,7 @@ clear_func_from_hash(struct ftrace_init_func *func, struct ftrace_hash *hash)
{
struct ftrace_func_entry *entry;

- if (ftrace_hash_empty(hash))
- return;
-
- entry = __ftrace_lookup_ip(hash, func->ip);
-
+ entry = ftrace_lookup_ip(hash, func->ip);
/*
* Do not allow this rec to match again.
* Yeah, it may waste some memory, but will be removed
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 005f08629b8b..74162bc4024d 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -941,11 +941,6 @@ static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)

preempt_disable_notrace();

- if (ftrace_hash_empty(ftrace_graph_hash)) {
- ret = 1;
- goto out;
- }
-
if (ftrace_lookup_ip(ftrace_graph_hash, addr)) {

/*
@@ -967,7 +962,6 @@ static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
ret = 1;
}

-out:
preempt_enable_notrace();
return ret;
}
--
2.20.1

2019-09-09 18:17:35

by Changbin Du

Subject: Re: [PATCH] ftrace: simplify ftrace hash lookup code

On Sun, Sep 08, 2019 at 08:05:45PM +0800, Changbin Du wrote:
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 005f08629b8b..74162bc4024d 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -941,11 +941,6 @@ static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
>
> preempt_disable_notrace();
>
> - if (ftrace_hash_empty(ftrace_graph_hash)) {
> - ret = 1;
> - goto out;
> - }
> -
Sorry, This remove is wrong. Will update change.

> if (ftrace_lookup_ip(ftrace_graph_hash, addr)) {
>
> /*
> @@ -967,7 +962,6 @@ static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
> ret = 1;
> }
>
> -out:
> preempt_enable_notrace();
> return ret;
> }
> --
> 2.20.1
>

--
Cheers,
Changbin Du