From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B6B343074A4 for ; Thu, 14 Aug 2025 09:31:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755163918; cv=none; b=CR6LYESwTgI94+Dg4VPnVbDcqo6fe2U3redx8t8RGUj0nH6oh+w8wkEKcEwMvK/Xt0jpXgan5uVwLvSAoEFS/iEbdDmtKyebmESKhLIVJo1lEyt+yTOOKsippWMqdijf0n/PxyYeRsjQsRKVTsBVR/Gl/b+QvtxrPX1g+qlyRmA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755163918; c=relaxed/simple; bh=lZyCdvmCPu4dSWES6kAli7yS99lbKG3WbFWtB+TIPv8=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=rwz4G97NMFVwXjgWuIMuXYLFkbmfoJtbK12+/v8kaDtzcm35roIzOiRB+IZ5MlVq35os0xD5EWGN6SY1MHsIYArlPQAGneDoW3kpffhC11vGW1u8Zz6sVw4riDxYnnrDxteSs94axkMY8I/EVKMRRq9Ee4uh9f892tcnrVzp7QU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.194]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4c2g313LRmztTJC; Thu, 14 Aug 2025 17:30:53 +0800 (CST) Received: from dggpemf500011.china.huawei.com (unknown [7.185.36.131]) by mail.maildlp.com (Postfix) with ESMTPS id 796DD14027A; Thu, 14 Aug 2025 17:31:53 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by dggpemf500011.china.huawei.com (7.185.36.131) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 14 Aug 2025 17:31:51 +0800 Message-ID: <7c342b54-553c-013e-bed0-bc723c20464a@huawei.com> Date: Thu, 14 Aug 2025 17:31:30 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH -next v7 5/7] arm64: entry: Refactor preempt_schedule_irq() check code Content-Language: en-US To: Mark Rutland CC: , , , , , , , , , , , , , , , , , , References: <20250729015456.3411143-1-ruanjinjie@huawei.com> <20250729015456.3411143-6-ruanjinjie@huawei.com> From: Jinjie Ruan In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To dggpemf500011.china.huawei.com (7.185.36.131) On 2025/8/12 19:13, Mark Rutland wrote: > On Tue, Jul 29, 2025 at 09:54:54AM +0800, Jinjie Ruan wrote: >> ARM64 requires an additional check whether to reschedule on return >> from interrupt. So add arch_irqentry_exit_need_resched() as the default >> NOP implementation and hook it up into the need_resched() condition in >> raw_irqentry_exit_cond_resched(). This allows ARM64 to implement >> the architecture specific version for switching over to >> the generic entry code. >> >> To align the structure of the code with irqentry_exit_cond_resched() >> from the generic entry code, hoist the need_irq_preemption() >> and IS_ENABLED() check earlier. And different preemption check functions >> are defined based on whether dynamic preemption is enabled. >> >> Suggested-by: Mark Rutland >> Suggested-by: Kevin Brodsky >> Suggested-by: Thomas Gleixner >> Signed-off-by: Jinjie Ruan >> --- >> arch/arm64/include/asm/preempt.h | 4 ++++ >> arch/arm64/kernel/entry-common.c | 35 ++++++++++++++++++-------------- >> kernel/entry/common.c | 16 ++++++++++++++- >> 3 files changed, 39 insertions(+), 16 deletions(-) > > Can you please split the change to kernel/entry/common.c into a separate > patch? That doesn't depend on the arm64-specific changes, and it'll make > it easier to handle any conflcits when merging this. Sure, I'll split the change into separate patch. > > Mark. > >> >> diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h >> index 0159b625cc7f..0f0ba250efe8 100644 >> --- a/arch/arm64/include/asm/preempt.h >> +++ b/arch/arm64/include/asm/preempt.h >> @@ -85,6 +85,7 @@ static inline bool should_resched(int preempt_offset) >> void preempt_schedule(void); >> void preempt_schedule_notrace(void); >> >> +void raw_irqentry_exit_cond_resched(void); >> #ifdef CONFIG_PREEMPT_DYNAMIC >> >> DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched); >> @@ -92,11 +93,14 @@ void dynamic_preempt_schedule(void); >> #define __preempt_schedule() dynamic_preempt_schedule() >> void dynamic_preempt_schedule_notrace(void); >> #define __preempt_schedule_notrace() dynamic_preempt_schedule_notrace() >> +void dynamic_irqentry_exit_cond_resched(void); >> +#define irqentry_exit_cond_resched() dynamic_irqentry_exit_cond_resched() >> >> #else /* CONFIG_PREEMPT_DYNAMIC */ >> >> #define __preempt_schedule() preempt_schedule() >> #define __preempt_schedule_notrace() preempt_schedule_notrace() >> +#define irqentry_exit_cond_resched() raw_irqentry_exit_cond_resched() >> >> #endif /* CONFIG_PREEMPT_DYNAMIC */ >> #endif /* CONFIG_PREEMPTION */ >> diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c >> index 7c2299c1ba79..4f92664fd46c 100644 >> --- a/arch/arm64/kernel/entry-common.c >> +++ b/arch/arm64/kernel/entry-common.c >> @@ -285,19 +285,8 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs, >> lockdep_hardirqs_on(CALLER_ADDR0); >> } >> >> -#ifdef CONFIG_PREEMPT_DYNAMIC >> -DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched); >> -#define need_irq_preemption() \ >> - (static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched)) >> -#else >> -#define need_irq_preemption() (IS_ENABLED(CONFIG_PREEMPTION)) >> -#endif >> - >> static inline bool arm64_preempt_schedule_irq(void) >> { >> - if (!need_irq_preemption()) >> - return false; >> - >> /* >> * DAIF.DA are cleared at the start of IRQ/FIQ handling, and when GIC >> * priority masking is used the GIC irqchip driver will clear DAIF.IF >> @@ -672,6 +661,24 @@ static __always_inline void __el1_pnmi(struct pt_regs *regs, >> arm64_exit_nmi(regs, state); >> } >> >> +void raw_irqentry_exit_cond_resched(void) >> +{ >> + if (!preempt_count()) { >> + if (need_resched() && arm64_preempt_schedule_irq()) >> + preempt_schedule_irq(); >> + } >> +} >> + >> +#ifdef CONFIG_PREEMPT_DYNAMIC >> +DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched); >> +void dynamic_irqentry_exit_cond_resched(void) >> +{ >> + if (!static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched)) >> + return; >> + raw_irqentry_exit_cond_resched(); >> +} >> +#endif >> + >> static __always_inline void __el1_irq(struct pt_regs *regs, >> void (*handler)(struct pt_regs *)) >> { >> @@ -681,10 +688,8 @@ static __always_inline void __el1_irq(struct pt_regs *regs, >> do_interrupt_handler(regs, handler); >> irq_exit_rcu(); >> >> - if (!preempt_count() && need_resched()) { >> - if (arm64_preempt_schedule_irq()) >> - preempt_schedule_irq(); >> - } >> + if (IS_ENABLED(CONFIG_PREEMPTION)) >> + irqentry_exit_cond_resched(); >> >> exit_to_kernel_mode(regs, state); >> } >> diff --git a/kernel/entry/common.c b/kernel/entry/common.c >> index b82032777310..4aa9656fa1b4 100644 >> --- a/kernel/entry/common.c >> +++ b/kernel/entry/common.c >> @@ -142,6 +142,20 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) >> return ret; >> } >> >> +/** >> + * arch_irqentry_exit_need_resched - Architecture specific need resched function >> + * >> + * Invoked from raw_irqentry_exit_cond_resched() to check if need resched. >> + * Defaults return true. >> + * >> + * The main purpose is to permit arch to skip preempt a task from an IRQ. >> + */ >> +static inline bool arch_irqentry_exit_need_resched(void); >> + >> +#ifndef arch_irqentry_exit_need_resched >> +static inline bool arch_irqentry_exit_need_resched(void) { return true; } >> +#endif >> + >> void raw_irqentry_exit_cond_resched(void) >> { >> if (!preempt_count()) { >> @@ -149,7 +163,7 @@ void raw_irqentry_exit_cond_resched(void) >> rcu_irq_exit_check_preempt(); >> if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) >> WARN_ON_ONCE(!on_thread_stack()); >> - if (need_resched()) >> + if (need_resched() && arch_irqentry_exit_need_resched()) >> preempt_schedule_irq(); >> } >> } >> -- >> 2.34.1 >> > >