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tracing: Annotate ftrace_graph_hash pointer with __rcu

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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>
This commit is contained in:
Amol Grover 2020-02-01 12:57:04 +05:30 committed by Steven Rostedt (VMware)
parent 7495e0926f
commit 24a9729f83
2 changed files with 7 additions and 4 deletions
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2
kernel/trace/ftrace.c
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@ -5591,7 +5591,7 @@ static const struct file_operations ftrace_notrace_fops = {
static DEFINE_MUTEX(graph_lock); 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; struct ftrace_hash *ftrace_graph_notrace_hash = EMPTY_HASH;
enum graph_filter_type { enum graph_filter_type {

9
kernel/trace/trace.h
View File

@ -964,22 +964,25 @@ extern void __trace_graph_return(struct trace_array *tr,
unsigned long flags, int pc); unsigned long flags, int pc);
#ifdef CONFIG_DYNAMIC_FTRACE #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; extern struct ftrace_hash *ftrace_graph_notrace_hash;
static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace) static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
{ {
unsigned long addr = trace->func; unsigned long addr = trace->func;
int ret = 0; int ret = 0;
struct ftrace_hash *hash;
preempt_disable_notrace(); 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; ret = 1;
goto out; goto out;
} }
if (ftrace_lookup_ip(ftrace_graph_hash, addr)) { if (ftrace_lookup_ip(hash, addr)) {
/* /*
* This needs to be cleared on the return functions * This needs to be cleared on the return functions