From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 022AE266581 for ; Wed, 1 Apr 2026 21:52:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775080356; cv=none; b=ndAS1hEzeg1GYjBwpgSiuFjJyPq6kuWTtDHkkBU6D6XVLg6TkFlAdaZ+2iyWqIM54QChSPISdiYK9OxCXzHXEPKLm3nAT90TmY8zspTSKE4gA/AXgjkREX5O708LJQUnACuJStqQRoBSB8wbLL0LXOi0rDyUGtDQck6fI/xx4So= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775080356; c=relaxed/simple; bh=LyBb4NlgnMJSstFYZVvzc9X6THYd3LNw7IL/HCjsmqQ=; h=Date:Message-ID:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=WJ8G0HKs58HeXMVoiwEFjboLP79uaQ+8XlQ4WAQM1Sbwbr6A78Anh9ZZcIzhTST7TFbR1ro9bzbdrMaMBMxpDIRcaUZLBdR/LsLT79tarwvcrujHsvsLwQEGq5fHQihNsPa9cAtsLHjSlRGNW3ORODD8bx42i1ZyhB2bZXFaPJk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hZPNMbm3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hZPNMbm3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1FE71C4CEF7; Wed, 1 Apr 2026 21:52:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775080355; bh=LyBb4NlgnMJSstFYZVvzc9X6THYd3LNw7IL/HCjsmqQ=; h=Date:From:To:Cc:Subject:References:From; b=hZPNMbm3vsbJD+cwQxHL95dLqzU3f4KpNKQS5VPyT3k0CVBmgVu65eWmJwY0k1RsK WJm8YIKoiBXdsPvRj9pJVxxgcJSsS2Uayxhql3TurBjKFybXOGHCCY6sfp620SONe6 BXF6nP3ul0dS+0Fn25pI8PXaS/4HAGy8QwlNE5miOONodV+wosgbYPhMS8VTYQugKw YY9v1p6dYmeznd5Vp62ibEJH3O1r6dv+C9nJiaew/VliDhiustiDRXNgsNt9GNwX0J G6ym8iaTLArOhCIOt3uIjxgVJ5zPCeyRAlaFiSD7BNygxwS23wTZYZvea2BoTo7LEq 8FMUttQKevZ1w== Date: Wed, 01 Apr 2026 23:52:32 +0200 Message-ID: <20260401201348.829256196@kernel.org> User-Agent: quilt/0.68 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Michael Kelley , Dmitry Ilvokhin , Radu Rendec , Jan Kiszka , Kieran Bingham , Florian Fainelli , Marc Zyngier Subject: [patch V5 12/15] genirq: Add rcuref count to struct irq_desc References: <20260401195625.213446764@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Thomas Gleixner Prepare for a smarter iterator for /proc/interrupts so that the next interrupt descriptor can be cached after lookup. Signed-off-by: Thomas Gleixner Reviewed-by: Dmitry Ilvokhin --- include/linux/irqdesc.h | 2 ++ kernel/irq/internals.h | 17 ++++++++++++++++- kernel/irq/irqdesc.c | 21 +++++++++++++-------- 3 files changed, 31 insertions(+), 9 deletions(-) --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -70,6 +70,7 @@ struct irq_redirect { * IRQF_NO_SUSPEND set * @force_resume_depth: number of irqactions on a irq descriptor with * IRQF_FORCE_RESUME set + * @refcnt: Reference count mainly for /proc/interrupts * @rcu: rcu head for delayed free * @kobj: kobject used to represent this struct in sysfs * @request_mutex: mutex to protect request/free before locking desc->lock @@ -119,6 +120,7 @@ struct irq_desc { struct dentry *debugfs_file; const char *dev_name; #endif + rcuref_t refcnt; #ifdef CONFIG_SPARSE_IRQ struct rcu_head rcu; struct kobject kobj; --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -9,6 +9,7 @@ #include #include #include +#include #include #ifdef CONFIG_SPARSE_IRQ @@ -101,9 +102,23 @@ extern void unmask_irq(struct irq_desc * extern void unmask_threaded_irq(struct irq_desc *desc); #ifdef CONFIG_SPARSE_IRQ -static inline void irq_mark_irq(unsigned int irq) { } +static __always_inline void irq_mark_irq(unsigned int irq) { } +void irq_desc_free_rcu(struct irq_desc *desc); + +static __always_inline bool irq_desc_get_ref(struct irq_desc *desc) +{ + return rcuref_get(&desc->refcnt); +} + +static __always_inline void irq_desc_put_ref(struct irq_desc *desc) +{ + if (rcuref_put(&desc->refcnt)) + irq_desc_free_rcu(desc); +} #else extern void irq_mark_irq(unsigned int irq); +static __always_inline bool irq_desc_get_ref(struct irq_desc *desc) { return true; } +static __always_inline void irq_desc_put_ref(struct irq_desc *desc) { } #endif irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc); --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -137,6 +137,7 @@ static void desc_set_defaults(unsigned i desc->tot_count = 0; desc->name = NULL; desc->owner = owner; + rcuref_init(&desc->refcnt, 1); desc_smp_init(desc, node, affinity); } @@ -465,6 +466,17 @@ static void delayed_free_desc(struct rcu kobject_put(&desc->kobj); } +void irq_desc_free_rcu(struct irq_desc *desc) +{ + /* + * We free the descriptor, masks and stat fields via RCU. That + * allows demultiplex interrupts to do rcu based management of + * the child interrupts. + * This also allows us to use rcu in kstat_irqs_usr(). + */ + call_rcu(&desc->rcu, delayed_free_desc); +} + static void free_desc(unsigned int irq) { struct irq_desc *desc = irq_to_desc(irq); @@ -483,14 +495,7 @@ static void free_desc(unsigned int irq) */ irq_sysfs_del(desc); delete_irq_desc(irq); - - /* - * We free the descriptor, masks and stat fields via RCU. That - * allows demultiplex interrupts to do rcu based management of - * the child interrupts. - * This also allows us to use rcu in kstat_irqs_usr(). - */ - call_rcu(&desc->rcu, delayed_free_desc); + irq_desc_put_ref(desc); } static int alloc_descs(unsigned int start, unsigned int cnt, int node,