From: james.morse@arm•com (James Morse)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 15/13] firmware: arm_sdei: move the frozen flag under the spinlock
Date: Wed, 08 Nov 2017 15:11:26 +0000 [thread overview]
Message-ID: <5A031E9E.2090809@arm.com> (raw)
In-Reply-To: <20171101155941.19432-1-james.morse@arm.com>
On 01/11/17 15:59, James Morse wrote:
> dpm_suspend() calls the freeze/thaw callbacks for hibernate before
> disable_non_bootcpus() takes down secondaries.
>
> This leads to a fun race where the freeze/thaw callbacks reset the
> SDEI interface (as we may be restoring a kernel with a different
> layout due to KASLR), then the cpu-hotplug callbacks come in to
> save the current state, which has already been reset.
>
> We solve this with a 'frozen' flag that stops the hotplug callback
> from overwriting the saved values.
>
> This patch moves the flag under the 'events' spinlock we take
> in the hotplug callbacks, to avoid depending on cpu-hotplug's
> mechanics to ensure the callback sees the correct value.
Scratch this. All this has really done is moved the race around. Will had a much
better suggestion that makes it look like all the CPUs are down. That makes
hotplug and power-management behave the same.
Thanks,
James
next prev parent reply other threads:[~2017-11-08 15:11 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-17 17:44 [PATCH v4 00/13] arm64/firmware: Software Delegated Exception Interface James Morse
2017-10-17 17:44 ` [PATCH v4 01/13] KVM: arm64: Store vcpu on the stack during __guest_enter() James Morse
2017-10-17 17:44 ` [PATCH v4 02/13] KVM: arm/arm64: Convert kvm_host_cpu_state to a static per-cpu allocation James Morse
2017-10-17 17:44 ` [PATCH v4 03/13] KVM: arm64: Change hyp_panic()s dependency on tpidr_el2 James Morse
2017-10-17 17:44 ` [PATCH v4 04/13] arm64: alternatives: use tpidr_el2 on VHE hosts James Morse
2017-10-18 11:00 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 05/13] KVM: arm64: Stop save/restoring host tpidr_el1 on VHE James Morse
2017-10-17 17:44 ` [PATCH v4 06/13] Docs: dt: add devicetree binding for describing arm64 SDEI firmware James Morse
2017-10-17 17:44 ` [PATCH v4 07/13] firmware: arm_sdei: Add driver for Software Delegated Exceptions James Morse
2017-10-18 11:09 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 08/13] arm64: Add vmap_stack header file James Morse
2017-10-18 11:10 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 09/13] arm64: kernel: Add arch-specific SDEI entry code and CPU masking James Morse
2017-10-18 11:18 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 10/13] firmware: arm_sdei: Add support for CPU and system power states James Morse
2017-10-18 11:11 ` Catalin Marinas
2017-10-18 17:17 ` Will Deacon
2017-10-24 17:34 ` James Morse
2017-10-25 14:43 ` Will Deacon
2017-10-17 17:44 ` [PATCH v4 11/13] firmware: arm_sdei: add support for CPU private events James Morse
2017-10-18 11:11 ` Catalin Marinas
2017-10-18 17:19 ` Will Deacon
2017-10-24 17:34 ` James Morse
2017-11-01 15:59 ` James Morse
2017-10-17 17:44 ` [PATCH v4 12/13] arm64: acpi: Remove __init from acpi_psci_use_hvc() for use by SDEI James Morse
2017-10-18 11:11 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 13/13] firmware: arm_sdei: Discover SDEI support via ACPI James Morse
2017-10-18 11:12 ` Catalin Marinas
2017-10-18 17:16 ` [PATCH v4 00/13] arm64/firmware: Software Delegated Exception Interface Will Deacon
2017-10-30 15:58 ` [PATCH v4 14/13] firmware: arm_sdei: Move cpuhotplug registration later James Morse
2017-11-01 15:59 ` [PATCH 15/13] firmware: arm_sdei: move the frozen flag under the spinlock James Morse
2017-11-08 15:11 ` James Morse [this message]
2017-11-08 16:06 ` [PATCH v4 15/13] firmware: arm_sdei: be more robust against cpu-hotplug James Morse
2017-11-13 11:01 ` Will Deacon
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