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From: Amol Grover <frextrite@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>,
	linux-kernel@vger.kernel.org,
	Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [Linux-kernel-mentees] [PATCH] tracing: Annotate ftrace_graph_hash pointer with __rcu
Date: Sat,  1 Feb 2020 12:57:04 +0530	[thread overview]
Message-ID: <20200201072703.17330-1-frextrite@gmail.com> (raw)

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.

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 kernel/trace/ftrace.c | 2 +-
 kernel/trace/trace.h  | 9 ++++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9bf1f2cd515e..959ded08dc13 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5596,7 +5596,7 @@ static const struct file_operations ftrace_notrace_fops = {
 
 static DEFINE_MUTEX(graph_lock);
 
-struct ftrace_hash *ftrace_graph_hash = EMPTY_HASH;
+struct ftrace_hash __rcu *ftrace_graph_hash = EMPTY_HASH;
 struct ftrace_hash *ftrace_graph_notrace_hash = EMPTY_HASH;
 
 enum graph_filter_type {
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 63bf60f79398..97dad3326020 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -950,22 +950,25 @@ extern void __trace_graph_return(struct trace_array *tr,
 				 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(struct ftrace_graph_ent *trace)
 {
 	unsigned long addr = trace->func;
 	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)) {
 
 		/*
 		 * This needs to be cleared on the return functions
-- 
2.24.1

_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

WARNING: multiple messages have this Message-ID (diff)
From: Amol Grover <frextrite@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org,
	Joel Fernandes <joel@joelfernandes.org>,
	Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Amol Grover <frextrite@gmail.com>
Subject: [PATCH] tracing: Annotate ftrace_graph_hash pointer with __rcu
Date: Sat,  1 Feb 2020 12:57:04 +0530	[thread overview]
Message-ID: <20200201072703.17330-1-frextrite@gmail.com> (raw)

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.

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 kernel/trace/ftrace.c | 2 +-
 kernel/trace/trace.h  | 9 ++++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9bf1f2cd515e..959ded08dc13 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5596,7 +5596,7 @@ static const struct file_operations ftrace_notrace_fops = {
 
 static DEFINE_MUTEX(graph_lock);
 
-struct ftrace_hash *ftrace_graph_hash = EMPTY_HASH;
+struct ftrace_hash __rcu *ftrace_graph_hash = EMPTY_HASH;
 struct ftrace_hash *ftrace_graph_notrace_hash = EMPTY_HASH;
 
 enum graph_filter_type {
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 63bf60f79398..97dad3326020 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -950,22 +950,25 @@ extern void __trace_graph_return(struct trace_array *tr,
 				 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(struct ftrace_graph_ent *trace)
 {
 	unsigned long addr = trace->func;
 	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)) {
 
 		/*
 		 * This needs to be cleared on the return functions
-- 
2.24.1


             reply	other threads:[~2020-02-01  7:28 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-01  7:27 Amol Grover [this message]
2020-02-01  7:27 ` [PATCH] tracing: Annotate ftrace_graph_hash pointer with __rcu Amol Grover
2020-02-03 16:33 ` [Linux-kernel-mentees] " Joel Fernandes
2020-02-03 16:33   ` Joel Fernandes
2020-02-04 10:02   ` [Linux-kernel-mentees] " Steven Rostedt
2020-02-04 10:02     ` Steven Rostedt
2020-02-05  1:01   ` [Linux-kernel-mentees] " Steven Rostedt
2020-02-05  1:01     ` Steven Rostedt
2020-02-05  5:26     ` [Linux-kernel-mentees] " Amol Grover
2020-02-05  5:26       ` Amol Grover
2020-02-05 13:11     ` [Linux-kernel-mentees] " Paul E. McKenney
2020-02-05 13:11       ` Paul E. McKenney
2020-02-05 13:14       ` [Linux-kernel-mentees] " Steven Rostedt
2020-02-05 13:14         ` Steven Rostedt
2020-02-05 13:19         ` [Linux-kernel-mentees] " Steven Rostedt
2020-02-05 13:19           ` Steven Rostedt
2020-02-05 13:29           ` [Linux-kernel-mentees] " Paul E. McKenney
2020-02-05 13:29             ` Paul E. McKenney
2020-02-05 22:06 ` [Linux-kernel-mentees] " Joel Fernandes
2020-02-05 22:06   ` Joel Fernandes

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