This is a note to let you know that I've just added the patch titled tracing: Annotate ftrace_graph_notrace_hash pointer with __rcu to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tracing-annotate-ftrace_graph_notrace_hash-pointer-w.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 3648a785ae0fef25dee2fc95227842f8ec82e03c Author: Amol Grover <frextrite@xxxxxxxxx> Date: Wed Feb 5 11:27:02 2020 +0530 tracing: Annotate ftrace_graph_notrace_hash pointer with __rcu [ 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@xxxxxxxxx Signed-off-by: Amol Grover <frextrite@xxxxxxxxx> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index b38c6af10da5b..d297a8bdc681a 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5103,7 +5103,7 @@ 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 f8fb3786af72a..c4fd5731d6b37 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -933,7 +933,7 @@ 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) { @@ -986,10 +986,14 @@ 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();