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Message-ID: <tip-0bd3a173d711857fc9f583eb5825386cc08f3948@git.kernel.org>
Date: Mon, 13 Jan 2014 08:42:25 -0800
From: tip-bot for Peter Zijlstra <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
arjan@...ux.intel.com, peterz@...radead.org, bitbucket@...ine.de,
tglx@...utronix.de
Subject: [tip:sched/core] sched/preempt, locking: Rework local_bh_{dis,
en}able()
Commit-ID: 0bd3a173d711857fc9f583eb5825386cc08f3948
Gitweb: http://git.kernel.org/tip/0bd3a173d711857fc9f583eb5825386cc08f3948
Author: Peter Zijlstra <peterz@...radead.org>
AuthorDate: Tue, 19 Nov 2013 16:13:38 +0100
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 13 Jan 2014 17:32:27 +0100
sched/preempt, locking: Rework local_bh_{dis,en}able()
Currently local_bh_disable() is out-of-line for no apparent reason.
So inline it to save a few cycles on call/return nonsense, the
function body is a single add on x86 (a few loads and store extra on
load/store archs).
Also expose two new local_bh functions:
__local_bh_{dis,en}able_ip(unsigned long ip, unsigned int cnt);
Which implement the actual local_bh_{dis,en}able() behaviour.
The next patch uses the exposed @cnt argument to optimize bh lock
functions.
With build fixes from Jacob Pan.
Cc: rjw@...ysocki.net
Cc: rui.zhang@...el.com
Cc: jacob.jun.pan@...ux.intel.com
Cc: Mike Galbraith <bitbucket@...ine.de>
Cc: hpa@...or.com
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: lenb@...nel.org
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/20131119151338.GF3694@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
include/linux/bottom_half.h | 32 +++++++++++++++++++++++++++++---
include/linux/hardirq.h | 1 +
include/linux/preempt_mask.h | 1 -
kernel/softirq.c | 35 ++++++-----------------------------
4 files changed, 36 insertions(+), 33 deletions(-)
diff --git a/include/linux/bottom_half.h b/include/linux/bottom_half.h
index 27b1bcf..86c12c9 100644
--- a/include/linux/bottom_half.h
+++ b/include/linux/bottom_half.h
@@ -1,9 +1,35 @@
#ifndef _LINUX_BH_H
#define _LINUX_BH_H
-extern void local_bh_disable(void);
+#include <linux/preempt.h>
+#include <linux/preempt_mask.h>
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+extern void __local_bh_disable_ip(unsigned long ip, unsigned int cnt);
+#else
+static __always_inline void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
+{
+ preempt_count_add(cnt);
+ barrier();
+}
+#endif
+
+static inline void local_bh_disable(void)
+{
+ __local_bh_disable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
+}
+
extern void _local_bh_enable(void);
-extern void local_bh_enable(void);
-extern void local_bh_enable_ip(unsigned long ip);
+extern void __local_bh_enable_ip(unsigned long ip, unsigned int cnt);
+
+static inline void local_bh_enable_ip(unsigned long ip)
+{
+ __local_bh_enable_ip(ip, SOFTIRQ_DISABLE_OFFSET);
+}
+
+static inline void local_bh_enable(void)
+{
+ __local_bh_enable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
+}
#endif /* _LINUX_BH_H */
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index d9cf963..12d5f97 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -5,6 +5,7 @@
#include <linux/lockdep.h>
#include <linux/ftrace_irq.h>
#include <linux/vtime.h>
+#include <asm/hardirq.h>
extern void synchronize_irq(unsigned int irq);
diff --git a/include/linux/preempt_mask.h b/include/linux/preempt_mask.h
index b8d96bc..dbeec4d 100644
--- a/include/linux/preempt_mask.h
+++ b/include/linux/preempt_mask.h
@@ -2,7 +2,6 @@
#define LINUX_PREEMPT_MASK_H
#include <linux/preempt.h>
-#include <asm/hardirq.h>
/*
* We put the hardirq and softirq counter into the preemption
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 7500cce1..9e368ef 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -89,7 +89,7 @@ static void wakeup_softirqd(void)
* where hardirqs are disabled legitimately:
*/
#ifdef CONFIG_TRACE_IRQFLAGS
-static void __local_bh_disable(unsigned long ip, unsigned int cnt)
+void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
{
unsigned long flags;
@@ -114,21 +114,9 @@ static void __local_bh_disable(unsigned long ip, unsigned int cnt)
if (preempt_count() == cnt)
trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
}
-#else /* !CONFIG_TRACE_IRQFLAGS */
-static inline void __local_bh_disable(unsigned long ip, unsigned int cnt)
-{
- preempt_count_add(cnt);
- barrier();
-}
+EXPORT_SYMBOL(__local_bh_disable_ip);
#endif /* CONFIG_TRACE_IRQFLAGS */
-void local_bh_disable(void)
-{
- __local_bh_disable(_RET_IP_, SOFTIRQ_DISABLE_OFFSET);
-}
-
-EXPORT_SYMBOL(local_bh_disable);
-
static void __local_bh_enable(unsigned int cnt)
{
WARN_ON_ONCE(!irqs_disabled());
@@ -151,7 +139,7 @@ void _local_bh_enable(void)
EXPORT_SYMBOL(_local_bh_enable);
-static inline void _local_bh_enable_ip(unsigned long ip)
+void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
{
WARN_ON_ONCE(in_irq() || irqs_disabled());
#ifdef CONFIG_TRACE_IRQFLAGS
@@ -166,7 +154,7 @@ static inline void _local_bh_enable_ip(unsigned long ip)
* Keep preemption disabled until we are done with
* softirq processing:
*/
- preempt_count_sub(SOFTIRQ_DISABLE_OFFSET - 1);
+ preempt_count_sub(cnt - 1);
if (unlikely(!in_interrupt() && local_softirq_pending())) {
/*
@@ -182,18 +170,7 @@ static inline void _local_bh_enable_ip(unsigned long ip)
#endif
preempt_check_resched();
}
-
-void local_bh_enable(void)
-{
- _local_bh_enable_ip(_RET_IP_);
-}
-EXPORT_SYMBOL(local_bh_enable);
-
-void local_bh_enable_ip(unsigned long ip)
-{
- _local_bh_enable_ip(ip);
-}
-EXPORT_SYMBOL(local_bh_enable_ip);
+EXPORT_SYMBOL(__local_bh_enable_ip);
/*
* We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
@@ -230,7 +207,7 @@ asmlinkage void __do_softirq(void)
pending = local_softirq_pending();
account_irq_enter_time(current);
- __local_bh_disable(_RET_IP_, SOFTIRQ_OFFSET);
+ __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
lockdep_softirq_enter();
cpu = smp_processor_id();
--
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