linux-kernel - [PATCH v1 0/3] ACPI: OSL/EC: Use spin locks without disabling interrupts

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Date: Fri, 15 Dec 2023 12:23:54 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux ACPI <linux-acpi@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Zhang Rui <rui.zhang@...el.com>, Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>, Michal Wilczynski <michal.wilczynski@...el.com>, Hans de Goede <hdegoede@...hat.com>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Mika Westerberg <mika.westerberg@...ux.intel.com>, Heikki Krogerus <heikki.krogerus@...ux.intel.com>, Mario Limonciello <mario.limonciello@....com>, Daniel Drake <drake@...lessm.com>
Subject: [PATCH v1 0/3] ACPI: OSL/EC: Use spin locks without disabling interrupts

Hi Everyone,

After

https://patchwork.kernel.org/project/linux-acpi/patch/5745568.DvuYhMxLoT@kreacher/

the SCI interrupt handler is threaded, so ACPICA spin locks can be used without
disabling interrupts, because they cannot be acquired from a hardirq handler
running on the same CPU as any code already holding the spin lock.  This patch
[1/3] removes disabling interrupts from acpi_os_acquire_lock() and updates
acpi_os_release_lock() accordingly.

Patch [2/2] uses the observation that if acpi_handle_interrupt() can run
in a threaded interrupt handler in the GPE case, it can also run in a threaded
interrupt handler in the dedicated IRQ case, so it makes the EC driver use a
threaded handler for the dedicated EC interrupt.

Patch [3/3], in analogy with patch [1/3], uses the observation that after patch
[2/2] all of the EC code runs in thread context, so it need not disable
interrupts on the local CPU before acquiring a spin lock, so the EC driver is
updated to operate its spin lock without disabling interrupts.

Thanks!