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From:   Jason Liu <jason.hui.liu@nxp.com>
To:     linux-arm-kernel@lists.infradead.org
Cc:     linux-kernel@vger.kernel.org
Subject: [PATCH 1/1] arm64: kexec: no need to do irq_chip->irq_mask if it already masked
Date:   Thu,  2 Jul 2020 17:27:22 +0800
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No need to do the irq_chip->irq_mask() if it already masked.
BTW, unconditionally do the irq_chip->irq_mask() will also bring issues
when the irq_chip in the runtime PM suspend. Accessing registers of the
irq_chip will bring in the exceptions. For example on the i.MX:

root@imx8qmmek:~# echo c > /proc/sysrq-trigger
[  177.796182] sysrq: Trigger a crash
[  177.799596] Kernel panic - not syncing: sysrq triggered crash
[  177.875616] SMP: stopping secondary CPUs
[  177.891936] Internal error: synchronous external abort: 96000210 [#1] PREEMPT SMP
[  177.899429] Modules linked in: crct10dif_ce mxc_jpeg_encdec
[  177.905018] CPU: 1 PID: 944 Comm: sh Kdump: loaded Not tainted
[  177.913457] Hardware name: Freescale i.MX8QM MEK (DT)
[  177.918517] pstate: a0000085 (NzCv daIf -PAN -UAO)
[  177.923318] pc : imx_irqsteer_irq_mask+0x50/0x80
[  177.927944] lr : imx_irqsteer_irq_mask+0x38/0x80
[  177.932561] sp : ffff800011fe3a50
[  177.935880] x29: ffff800011fe3a50 x28: ffff0008f7708e00
[  177.941196] x27: 0000000000000000 x26: 0000000000000000
[  177.946513] x25: ffff800011a30c80 x24: 0000000000000000
[  177.951830] x23: ffff800011fe3af8 x22: ffff0008f24469d4
[  177.957147] x21: ffff0008f2446880 x20: ffff0008f25f5658
[  177.962463] x19: ffff800012611004 x18: 0000000000000001
[  177.967780] x17: 0000000000000000 x16: 0000000000000000
[  177.973097] x15: ffff0008f7709270 x14: 0000000060000085
[  177.978414] x13: ffff800010177570 x12: ffff800011fe3ab0
[  177.983730] x11: ffff80001017749c x10: 0000000000000040
[  177.989047] x9 : ffff8000119f1c80 x8 : ffff8000119f1c78
[  177.994364] x7 : ffff0008f46bedf8 x6 : 0000000000000000
[  177.999681] x5 : ffff0008f46beda0 x4 : 0000000000000000
[  178.004997] x3 : ffff0008f24469d4 x2 : ffff800012611000
[  178.010314] x1 : 0000000000000080 x0 : 0000000000000080
[  178.015630] Call trace:
[  178.018077]  imx_irqsteer_irq_mask+0x50/0x80
[  178.022352]  machine_crash_shutdown+0xa8/0x100
[  178.026802]  __crash_kexec+0x6c/0x118
[  178.030464]  panic+0x19c/0x324
[  178.033524]  sysrq_handle_reboot+0x0/0x20
[  178.037537]  __handle_sysrq+0x88/0x180
[  178.041290]  write_sysrq_trigger+0x8c/0xb0
[  178.045389]  proc_reg_write+0x78/0xb0
[  178.049055]  __vfs_write+0x18/0x40
[  178.052461]  vfs_write+0xdc/0x1c8
[  178.055779]  ksys_write+0x68/0xf0
[  178.059098]  __arm64_sys_write+0x18/0x20
[  178.063027]  el0_svc_common.constprop.0+0x68/0x160
[  178.067821]  el0_svc_handler+0x20/0x80
[  178.071573]  el0_svc+0x8/0xc
[  178.074463] Code: 93407e73 91001273 aa0003e1 8b130053 (b9400260)
[  178.080567] ---[ end trace 652333f6c6d6b05d ]---

Signed-off-by: Jason Liu <jason.hui.liu@nxp.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
---
 arch/arm64/kernel/machine_kexec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index a0b144cfaea7..8ab263c733bf 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -236,7 +236,7 @@ static void machine_kexec_mask_interrupts(void)
 		    chip->irq_eoi)
 			chip->irq_eoi(&desc->irq_data);
 
-		if (chip->irq_mask)
+		if (chip->irq_mask && !irqd_irq_masked(&desc->irq_data))
 			chip->irq_mask(&desc->irq_data);
 
 		if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
-- 
2.27.0