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Date: Fri, 16 Sep 2016 07:53:46 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>,
linux-rt-users <linux-rt-users@...r.kernel.org>,
Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [ANNOUNCE] 4.6.7-rt13
On 2016-09-15 18:52:26 [+0200], To Thomas Gleixner wrote:
> The delta patch against 4.6.7-rt12 is appended below and can be found here:
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index 190af4271b5c..58fd4ff3f53a 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -89,6 +89,8 @@ static __always_inline bool __preempt_count_dec_and_test(void)
if (____preempt_count_dec_and_test())
return true;
#ifdef CONFIG_PREEMPT_LAZY
+ if (current_thread_info()->preempt_lazy_count)
+ return false;
return test_thread_flag(TIF_NEED_RESCHED_LAZY);
#else
return false;
@@ -101,8 +103,19 @@ static __always_inline bool __preempt_count_dec_and_test(void)
static __always_inline bool should_resched(int preempt_offset)
{
#ifdef CONFIG_PREEMPT_LAZY
- return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset ||
- test_thread_flag(TIF_NEED_RESCHED_LAZY));
+ u32 tmp;
+
+ tmp = raw_cpu_read_4(__preempt_count);
+ if (tmp == preempt_offset)
+ return true;
+
+ /* preempt count == 0 ? */
+ tmp &= ~PREEMPT_NEED_RESCHED;
+ if (tmp)
+ return false;
+ if (current_thread_info()->preempt_lazy_count)
+ return false;
+ return test_thread_flag(TIF_NEED_RESCHED_LAZY);
#else
return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset);
#endif
diff --git a/fs/dcache.c b/fs/dcache.c
index aa418c1bdcb5..90b66896ccb2 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -40,8 +40,6 @@
#include <linux/ratelimit.h>
#include <linux/list_lru.h>
#include <linux/kasan.h>
-#include <linux/sched/rt.h>
-#include <linux/sched/deadline.h>
#include "internal.h"
#include "mount.h"
@@ -795,10 +793,11 @@ void dput(struct dentry *dentry)
if (parent == dentry) {
/* the task with the highest priority won't schedule */
r = cond_resched();
- if (!r && (rt_task(current) || dl_task(current)))
+ if (!r)
cpu_chill();
- } else
+ } else {
dentry = parent;
+ }
goto repeat;
}
}
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index dea12a6e413b..72cb21071425 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -713,6 +713,7 @@ 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))
+#ifdef CONFIG_USING_GET_LOCK_PARENT_IP
static inline unsigned long get_lock_parent_ip(void)
{
unsigned long addr = CALLER_ADDR0;
@@ -724,6 +725,7 @@ static inline unsigned long get_lock_parent_ip(void)
return addr;
return CALLER_ADDR2;
}
+#endif
#ifdef CONFIG_IRQSOFF_TRACER
extern void time_hardirqs_on(unsigned long a0, unsigned long a1);
diff --git a/kernel/Makefile b/kernel/Makefile
index f0c40bf49d9f..c60cc9130374 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -11,6 +11,13 @@ obj-y = fork.o exec_domain.o panic.o \
notifier.o ksysfs.o cred.o reboot.o \
async.o range.o smpboot.o
+# Tracing may do some dangerous __builtin_return_address() operations
+# We know they are dangerous, we don't need gcc telling us that.
+ifdef CONFIG_USING_GET_LOCK_PARENT_IP
+FRAME_CFLAGS := $(call cc-disable-warning,frame-address)
+KBUILD_CFLAGS += $(FRAME_CFLAGS)
+endif
+
obj-$(CONFIG_MULTIUSER) += groups.o
ifdef CONFIG_FUNCTION_TRACER
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 364ccd0eb57b..9aae45fae52a 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -215,6 +215,7 @@ config PREEMPT_TRACER
select RING_BUFFER_ALLOW_SWAP
select TRACER_SNAPSHOT
select TRACER_SNAPSHOT_PER_CPU_SWAP
+ select USING_GET_LOCK_PARENT_IP
help
This option measures the time spent in preemption-off critical
sections, with microsecond accuracy.
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1e9a607534ca..0adcc993f372 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -962,6 +962,7 @@ config TIMER_STATS
config DEBUG_PREEMPT
bool "Debug preemptible kernel"
depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
+ select USING_GET_LOCK_PARENT_IP
default y
help
If you say Y here then the kernel will use a debug variant of the
@@ -1144,8 +1145,17 @@ config LOCK_TORTURE_TEST
endmenu # lock debugging
+config USING_GET_LOCK_PARENT_IP
+ bool
+ help
+ Enables the use of the function get_lock_parent_ip() that
+ will use __builtin_return_address(n) with n > 0 causing
+ some gcc warnings. When this is selected, those warnings
+ will be suppressed.
+
config TRACE_IRQFLAGS
bool
+ select USING_GET_LOCK_PARENT_IP
help
Enables hooks to interrupt enabling and disabling for
either tracing or lock debugging.
diff --git a/localversion-rt b/localversion-rt
index 6e44e540b927..9f7d0bdbffb1 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt12
+-rt13
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