[tip:sched/core] sched/debug: Fix preempt_disable_ip recording for preempt_disable()

From: tip-bot for Sebastian Andrzej Siewior
Date: Mon Feb 29 2016 - 06:20:04 EST


Commit-ID: f904f58263e1df5f70feb8b283f4bbe662847334
Gitweb: http://git.kernel.org/tip/f904f58263e1df5f70feb8b283f4bbe662847334
Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
AuthorDate: Fri, 26 Feb 2016 14:54:56 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
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@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20160226135456.GB18244@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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);