From: Amol Grover <frextrite@gmail.com>
Date: Sat, 1 Feb 2020 12:57:04 +0530
Subject: tracing: Annotate ftrace_graph_hash pointer with __rcu
Git-commit: 24a9729f831462b1d9d61dc85ecc91c59037243f
Patch-mainline: v5.6-rc1
References: git-fixes
Fix following instances of sparse error
kernel/trace/ftrace.c:5664:29: error: incompatible types in comparison
kernel/trace/ftrace.c:5785:21: error: incompatible types in comparison
kernel/trace/ftrace.c:5864:36: error: incompatible types in comparison
kernel/trace/ftrace.c:5866:25: error: incompatible types in comparison
Use rcu_dereference_protected to access the __rcu annotated pointer.
Link: http://lkml.kernel.org/r/20200201072703.17330-1-frextrite@gmail.com
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Amol Grover <frextrite@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Miroslav Benes <mbenes@suse.cz>
---
kernel/trace/ftrace.c | 2 +-
kernel/trace/trace.h | 9 ++++++---
2 files changed, 7 insertions(+), 4 deletions(-)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4806,7 +4806,7 @@ static const struct file_operations ftra
static DEFINE_MUTEX(graph_lock);
-struct ftrace_hash *ftrace_graph_hash = EMPTY_HASH;
+struct ftrace_hash __rcu *ftrace_graph_hash = EMPTY_HASH;
struct ftrace_hash *ftrace_graph_notrace_hash = EMPTY_HASH;
enum graph_filter_type {
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -811,21 +811,24 @@ extern void __trace_graph_return(struct
unsigned long flags, int pc);
#ifdef CONFIG_DYNAMIC_FTRACE
-extern struct ftrace_hash *ftrace_graph_hash;
+extern struct ftrace_hash __rcu *ftrace_graph_hash;
extern struct ftrace_hash *ftrace_graph_notrace_hash;
static inline int ftrace_graph_addr(unsigned long addr)
{
int ret = 0;
+ struct ftrace_hash *hash;
preempt_disable_notrace();
- if (ftrace_hash_empty(ftrace_graph_hash)) {
+ hash = rcu_dereference_protected(ftrace_graph_hash, !preemptible());
+
+ if (ftrace_hash_empty(hash)) {
ret = 1;
goto out;
}
- if (ftrace_lookup_ip(ftrace_graph_hash, addr)) {
+ if (ftrace_lookup_ip(hash, addr)) {
/*
* If no irqs are to be traced, but a set_graph_function
* is set, and called by an interrupt handler, we still