linux-kernel - [PATCH V2 -fixes] riscv: kexec: Avoid deadlock in kexec crash path

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Date: Wed, 26 Jun 2024 10:33:16 +0800
From: Song Shuai <songshuaishuai@...ylab.org>
To: takakura@...inux.co.jp,
	alex@...ti.fr,
	paul.walmsley@...ive.com,
	palmer@...belt.com
Cc: aou@...s.berkeley.edu,
	bhe@...hat.com,
	songshuaishuai@...ylab.org,
	akpm@...ux-foundation.org,
	guoren@...nel.org,
	xianting.tian@...ux.alibaba.com,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH V2 -fixes] riscv: kexec: Avoid deadlock in kexec crash path

If the kexec crash code is called in the interrupt context, the
machine_kexec_mask_interrupts() function will trigger a deadlock while
trying to acquire the irqdesc spinlock and then deactivate irqchip in
irq_set_irqchip_state() function.

Unlike arm64, riscv only requires irq_eoi handler to complete EOI and
keeping irq_set_irqchip_state() will only leave this possible deadlock
without any use. So we simply remove it.

Link: https://lore.kernel.org/linux-riscv/20231208111015.173237-1-songshuaishuai@tinylab.org/
Fixes: b17d19a5314a ("riscv: kexec: Fixup irq controller broken in kexec crash path")
Signed-off-by: Song Shuai <songshuaishuai@...ylab.org>
---
Changes since V1:
https://lore.kernel.org/linux-riscv/20231208111015.173237-1-songshuaishuai@tinylab.org/
- update the commit log as @Ryo elaborated 
- rebase on Linux 6.10-rc3

---
 arch/riscv/kernel/machine_kexec.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/arch/riscv/kernel/machine_kexec.c b/arch/riscv/kernel/machine_kexec.c
index ed9cad20c039..3c830a6f7ef4 100644
--- a/arch/riscv/kernel/machine_kexec.c
+++ b/arch/riscv/kernel/machine_kexec.c
@@ -121,20 +121,12 @@ static void machine_kexec_mask_interrupts(void)
 
 	for_each_irq_desc(i, desc) {
 		struct irq_chip *chip;
-		int ret;
 
 		chip = irq_desc_get_chip(desc);
 		if (!chip)
 			continue;
 
-		/*
-		 * First try to remove the active state. If this
-		 * fails, try to EOI the interrupt.
-		 */
-		ret = irq_set_irqchip_state(i, IRQCHIP_STATE_ACTIVE, false);
-
-		if (ret && irqd_irq_inprogress(&desc->irq_data) &&
-		    chip->irq_eoi)
+		if (chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
 			chip->irq_eoi(&desc->irq_data);
 
 		if (chip->irq_mask)
-- 
2.39.2