[PATCH 5.5 151/367] tracing: Annotate ftrace_graph_notrace_hash pointer with __rcu

Greg Kroah-Hartman
2020-02-10T12:50:34Z

From: Amol Grover <frextrite@gmail.com>

[ Upstream commit fd0e6852c407dd9aefc594f54ddcc21d84803d3b ]

Fix following instances of sparse error
kernel/trace/ftrace.c:5667:29: error: incompatible types in comparison
kernel/trace/ftrace.c:5813:21: error: incompatible types in comparison
kernel/trace/ftrace.c:5868:36: error: incompatible types in comparison
kernel/trace/ftrace.c:5870:25: error: incompatible types in comparison

Use rcu_dereference_protected to dereference the newly annotated pointer.

Link: http://lkml.kernel.org/r/20200205055701.30195-1-frextrite@gmail.com

Signed-off-by: Amol Grover <frextrite@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/trace/ftrace.c | 2 +-
kernel/trace/trace.h | 8 ++++++--
2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 959ded08dc13f..e85668cdd8c73 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5597,7 +5597,7 @@ static const struct file_operations ftrace_notrace_fops = {
static DEFINE_MUTEX(graph_lock);

struct ftrace_hash __rcu *ftrace_graph_hash = EMPTY_HASH;
-struct ftrace_hash *ftrace_graph_notrace_hash = EMPTY_HASH;
+struct ftrace_hash __rcu *ftrace_graph_notrace_hash = EMPTY_HASH;

enum graph_filter_type {
GRAPH_FILTER_NOTRACE = 0,
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 97dad33260208..497defe9ed264 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -951,7 +951,7 @@ extern void __trace_graph_return(struct trace_array *tr,

#ifdef CONFIG_DYNAMIC_FTRACE
extern struct ftrace_hash __rcu *ftrace_graph_hash;
-extern struct ftrace_hash *ftrace_graph_notrace_hash;
+extern struct ftrace_hash __rcu *ftrace_graph_notrace_hash;

static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
{
@@ -1004,10 +1004,14 @@ static inline void ftrace_graph_addr_finish(struct ftrace_graph_ret *trace)
static inline int ftrace_graph_notrace_addr(unsigned long addr)
{
int ret = 0;
+ struct ftrace_hash *notrace_hash;

preempt_disable_notrace();

- if (ftrace_lookup_ip(ftrace_graph_notrace_hash, addr))
+ notrace_hash = rcu_dereference_protected(ftrace_graph_notrace_hash,
+ !preemptible());
+
+ if (ftrace_lookup_ip(notrace_hash, addr))
ret = 1;

preempt_enable_notrace();
--
2.20.1