From 0bd3a173d711857fc9f583eb5825386cc08f3948 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 19 Nov 2013 16:13:38 +0100 Subject: [PATCH] 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@rjwysocki.net Cc: rui.zhang@intel.com Cc: jacob.jun.pan@linux.intel.com Cc: Mike Galbraith Cc: hpa@zytor.com Cc: Arjan van de Ven Cc: lenb@kernel.org Reviewed-by: Thomas Gleixner Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20131119151338.GF3694@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- 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 27b1bcffe408..86c12c93e3cf 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 +#include + +#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 d9cf963ac832..12d5f972f23f 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -5,6 +5,7 @@ #include #include #include +#include extern void synchronize_irq(unsigned int irq); diff --git a/include/linux/preempt_mask.h b/include/linux/preempt_mask.h index b8d96bca4357..dbeec4d4a3be 100644 --- a/include/linux/preempt_mask.h +++ b/include/linux/preempt_mask.h @@ -2,7 +2,6 @@ #define LINUX_PREEMPT_MASK_H #include -#include /* * We put the hardirq and softirq counter into the preemption diff --git a/kernel/softirq.c b/kernel/softirq.c index 7500cce1ebfd..9e368ef35f9a 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();