* [Linux-kernel-mentees] [PATCH] tracing: Annotate ftrace_graph_notrace_hash pointer with __rcu
@ 2020-02-05 5:57 Amol Grover
0 siblings, 0 replies; only message in thread
From: Amol Grover @ 2020-02-05 5:57 UTC (permalink / raw)
To: Steven Rostedt, Ingo Molnar
Cc: Paul E . McKenney, linux-kernel, Madhuparna Bhowmik,
Joel Fernandes, linux-kernel-mentees
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.
Signed-off-by: Amol Grover <frextrite@gmail.com>
---
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 9bf1f2cd515e..3a310c0c3ae3 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 *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 63bf60f79398..8c78bd6d53ca 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 *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)
{
@@ -1001,10 +1001,14 @@ 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();
--
2.24.1
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