linux-kernel - [tip:sched/core] sched/debug: Fix preempt_disable_ip recording for preempt

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Message-ID: <tip-f904f58263e1df5f70feb8b283f4bbe662847334@git.kernel.org>
Date:	Mon, 29 Feb 2016 03:19:19 -0800
From:	tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, peterz@...radead.org, hpa@...or.com,
	tglx@...utronix.de, efault@....de, rostedt@...dmis.org,
	bigeasy@...utronix.de, linux-kernel@...r.kernel.org,
	mingo@...nel.org
Subject: [tip:sched/core] sched/debug: Fix preempt_disable_ip recording for
 preempt_disable()

Commit-ID:  f904f58263e1df5f70feb8b283f4bbe662847334
Gitweb:     http://git.kernel.org/tip/f904f58263e1df5f70feb8b283f4bbe662847334
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Fri, 26 Feb 2016 14:54:56 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 29 Feb 2016 09:53:10 +0100

sched/debug: Fix preempt_disable_ip recording for preempt_disable()

The preempt_disable() invokes preempt_count_add() which saves the caller
in ->preempt_disable_ip. It uses CALLER_ADDR1 which does not look for
its caller but for the parent of the caller. Which means we get the correct
caller for something like spin_lock() unless the architectures inlines
those invocations. It is always wrong for preempt_disable() or
local_bh_disable().

This patch makes the function get_lock_parent_ip() which tries
CALLER_ADDR0,1,2 if the former is a locking function.
This seems to record the preempt_disable() caller properly for
preempt_disable() itself as well as for get_cpu_var() or
local_bh_disable().

Steven asked for the get_parent_ip() -> get_lock_parent_ip() rename.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/20160226135456.GB18244@linutronix.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 include/linux/ftrace.h | 12 ++++++++++++
 include/linux/sched.h  |  2 --
 kernel/sched/core.c    | 14 ++------------
 kernel/softirq.c       |  4 ++--
 4 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index c2b340e..6d9df3f 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -713,6 +713,18 @@ static inline void __ftrace_enabled_restore(int enabled)
 #define CALLER_ADDR5 ((unsigned long)ftrace_return_address(5))
 #define CALLER_ADDR6 ((unsigned long)ftrace_return_address(6))
 
+static inline unsigned long get_lock_parent_ip(void)
+{
+	unsigned long addr = CALLER_ADDR0;
+
+	if (!in_lock_functions(addr))
+		return addr;
+	addr = CALLER_ADDR1;
+	if (!in_lock_functions(addr))
+		return addr;
+	return CALLER_ADDR2;
+}
+
 #ifdef CONFIG_IRQSOFF_TRACER
   extern void time_hardirqs_on(unsigned long a0, unsigned long a1);
   extern void time_hardirqs_off(unsigned long a0, unsigned long a1);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 87e5f98..9519b66 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -182,8 +182,6 @@ extern void update_cpu_load_nohz(int active);
 static inline void update_cpu_load_nohz(int active) { }
 #endif
 
-extern unsigned long get_parent_ip(unsigned long addr);
-
 extern void dump_cpu_task(int cpu);
 
 struct seq_file;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6dbb21f..423452c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2946,16 +2946,6 @@ u64 scheduler_tick_max_deferment(void)
 }
 #endif
 
-notrace unsigned long get_parent_ip(unsigned long addr)
-{
-	if (in_lock_functions(addr)) {
-		addr = CALLER_ADDR2;
-		if (in_lock_functions(addr))
-			addr = CALLER_ADDR3;
-	}
-	return addr;
-}
-
 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
 				defined(CONFIG_PREEMPT_TRACER))
 
@@ -2977,7 +2967,7 @@ void preempt_count_add(int val)
 				PREEMPT_MASK - 10);
 #endif
 	if (preempt_count() == val) {
-		unsigned long ip = get_parent_ip(CALLER_ADDR1);
+		unsigned long ip = get_lock_parent_ip();
 #ifdef CONFIG_DEBUG_PREEMPT
 		current->preempt_disable_ip = ip;
 #endif
@@ -3004,7 +2994,7 @@ void preempt_count_sub(int val)
 #endif
 
 	if (preempt_count() == val)
-		trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
+		trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
 	__preempt_count_sub(val);
 }
 EXPORT_SYMBOL(preempt_count_sub);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 479e443..8aae49d 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -116,9 +116,9 @@ void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
 
 	if (preempt_count() == cnt) {
 #ifdef CONFIG_DEBUG_PREEMPT
-		current->preempt_disable_ip = get_parent_ip(CALLER_ADDR1);
+		current->preempt_disable_ip = get_lock_parent_ip();
 #endif
-		trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
+		trace_preempt_off(CALLER_ADDR0, get_lock_parent_ip());
 	}
 }
 EXPORT_SYMBOL(__local_bh_disable_ip);