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Thu, 28 Nov 2024 20:10:29 +0000 Received: from EX19MTAUEC001.ant.amazon.com (10.252.135.222) by EX19D018EUC003.ant.amazon.com (10.252.51.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Thu, 28 Nov 2024 20:10:28 +0000 Received: from email-imr-corp-prod-pdx-all-2b-22fa938e.us-west-2.amazon.com (10.124.125.6) by mail-relay.amazon.com (10.252.135.200) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34 via Frontend Transport; Thu, 28 Nov 2024 20:10:28 +0000 Received: from dev-dsk-farbere-1a-46ecabed.eu-west-1.amazon.com (dev-dsk-farbere-1a-46ecabed.eu-west-1.amazon.com [172.19.116.181]) by email-imr-corp-prod-pdx-all-2b-22fa938e.us-west-2.amazon.com (Postfix) with ESMTP id ADDF8C01D2; Thu, 28 Nov 2024 20:10:27 +0000 (UTC) Received: by dev-dsk-farbere-1a-46ecabed.eu-west-1.amazon.com (Postfix, from userid 14301484) id 46D0F78EA; Thu, 28 Nov 2024 20:10:27 +0000 (UTC) From: Eliav Farber To: , , , , , , , , , , , , , , , , , , , , , , , , , CC: Subject: [PATCH v3 2/2] kexec: Prevent redundant IRQ masking by checking state before shutdown Date: Thu, 28 Nov 2024 20:10:27 +0000 Message-ID: <20241128201027.10396-3-farbere@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20241128201027.10396-1-farbere@amazon.com> References: <20241128201027.10396-1-farbere@amazon.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain During machine kexec, the function machine_kexec_mask_interrupts() is responsible for disabling or masking all interrupts. While the irq_disable hook ensures that an already-disabled IRQ is not disabled again, the current implementation unconditionally invokes the irq_mask() function for every interrupt descriptor, even when the interrupt is already masked. A specific issue was observed in the crash kernel flow after unbinding a device (prior to kexec) that used a GPIO as an IRQ source. The warning was triggered by the gpiochip_disable_irq() function, which attempted to clear the FLAG_IRQ_IS_ENABLED flag when FLAG_USED_AS_IRQ was not set: ``` void gpiochip_disable_irq(struct gpio_chip *gc, unsigned int offset) { struct gpio_desc *desc = gpiochip_get_desc(gc, offset); if (!IS_ERR(desc) && !WARN_ON(!test_bit(FLAG_USED_AS_IRQ, &desc->flags))) clear_bit(FLAG_IRQ_IS_ENABLED, &desc->flags); } ``` This issue surfaced after commit a8173820f441 ("gpio: gpiolib: Allow GPIO IRQs to lazy disable") introduced lazy disablement for GPIO IRQs. It replaced disable/enable hooks with mask/unmask hooks. Unlike the disable hook, the mask hook doesn't handle already-masked IRQs. When a GPIO-IRQ driver is unbound, the IRQ is released, triggering __irq_disable() and irq_state_set_masked(). A subsequent call to machine_kexec_mask_interrupts() re-invokes chip->irq_mask(). This results in a call chain, including gpiochip_irq_mask() and gpiochip_disable_irq(). Since FLAG_USED_AS_IRQ was cleared earlier, a warning occurs. This patch addresses the issue by: - Replacing the calls to irq_mask() and irq_disable() hooks with a simplified call to irq_shutdown(). - Checking if the interrupt is started (irqd_is_started) before calling the shutdown. As part of this change, the irq_shutdown() declaration was moved from kernel/irq/internals.h to include/linux/irq.h to make it accessible outside the kernel/irq/ directory, as the former can only be included within that directory. Signed-off-by: Eliav Farber --- V2 -> V3: - Check if IRQ is started using irqd_is_started(). - Use irq_shutdown() instead of irq_disable(). include/linux/irq.h | 3 +++ kernel/irq/internals.h | 1 - kernel/kexec_core.c | 8 ++------ 3 files changed, 5 insertions(+), 7 deletions(-) diff --git a/include/linux/irq.h b/include/linux/irq.h index fa711f80957b..48a3df728c47 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -694,6 +694,9 @@ extern int irq_chip_request_resources_parent(struct irq_data *data); extern void irq_chip_release_resources_parent(struct irq_data *data); #endif +/* Shut down the interrupt */ +extern void irq_shutdown(struct irq_desc *desc); + /* Handling of unhandled and spurious interrupts: */ extern void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret); diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index fe0272cd84a5..1f9287b1ccb7 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -88,7 +88,6 @@ extern int irq_activate(struct irq_desc *desc); extern int irq_activate_and_startup(struct irq_desc *desc, bool resend); extern int irq_startup(struct irq_desc *desc, bool resend, bool force); -extern void irq_shutdown(struct irq_desc *desc); extern void irq_shutdown_and_deactivate(struct irq_desc *desc); extern void irq_enable(struct irq_desc *desc); extern void irq_disable(struct irq_desc *desc); diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 6e1e420946e0..928b4387502b 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -1083,7 +1083,7 @@ void machine_kexec_mask_interrupts(void) int check_eoi = 1; chip = irq_desc_get_chip(desc); - if (!chip) + if (!chip || !irqd_is_started(&desc->irq_data)) continue; if (IS_ENABLED(CONFIG_ARM64)) { @@ -1097,10 +1097,6 @@ void machine_kexec_mask_interrupts(void) if (check_eoi && chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data)) chip->irq_eoi(&desc->irq_data); - if (chip->irq_mask) - chip->irq_mask(&desc->irq_data); - - if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data)) - chip->irq_disable(&desc->irq_data); + irq_shutdown(desc); } } -- 2.40.1