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From: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
To: linux-pm@vger.kernel.org, loongarch@lists.linux.dev,
	linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-riscv@lists.infradead.org, kvmarm@lists.linux.dev,
	x86@kernel.org, acpica-devel@lists.linuxfoundation.org,
	linux-csky@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-ia64@vger.kernel.org, linux-parisc@vger.kernel.org
Cc: Salil Mehta <salil.mehta@huawei.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	jianyong.wu@arm.com, justin.he@arm.com,
	James Morse <james.morse@arm.com>,
	Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>
Subject: [PATCH RFC v4 05/15] ACPI: Add post_eject to struct acpi_scan_handler for cpu hotplug
Date: Wed, 31 Jan 2024 16:50:02 +0000	[thread overview]
Message-ID: <E1rVDmk-0027Yh-1E@rmk-PC.armlinux.org.uk> (raw)
In-Reply-To: <Zbp5xzmFhKDAgHws@shell.armlinux.org.uk>

From: James Morse <james.morse@arm.com>

struct acpi_scan_handler has a detach callback that is used to remove
a driver when a bus is changed. When interacting with an eject-request,
the detach callback is called before _EJ0.

This means the ACPI processor driver can't use _STA to determine if a
CPU has been made not-present, or some of the other _STA bits have been
changed. acpi_processor_remove() needs to know the value of _STA after
_EJ0 has been called.

Add a post_eject callback to struct acpi_scan_handler. This is called
after acpi_scan_hot_remove() has successfully called _EJ0. Because
acpi_bus_trim_one() also clears the handler pointer, it needs to be
told if the caller will go on to call acpi_bus_post_eject(), so
that acpi_device_clear_enumerated() and clearing the handler pointer
can be deferred. The existing not-used pointer is used for this.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Tested-by: Miguel Luis <miguel.luis@oracle.com>
Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
Tested-by: Jianyong Wu <jianyong.wu@arm.com>
---
Outstanding comments:
 https://lore.kernel.org/r/20230914152809.00003152@Huawei.com
 https://lore.kernel.org/r/c3ef8123-1fcc-7289-c475-c753de44d564@redhat.com
---
 drivers/acpi/acpi_processor.c |  4 +--
 drivers/acpi/scan.c           | 52 ++++++++++++++++++++++++++++++-----
 include/acpi/acpi_bus.h       |  1 +
 3 files changed, 48 insertions(+), 9 deletions(-)

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index fd8f3a0572cb..00809c3b09f7 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -459,7 +459,7 @@ static int acpi_processor_add(struct acpi_device *device,
 
 #ifdef CONFIG_ACPI_HOTPLUG_CPU
 /* Removal */
-static void acpi_processor_remove(struct acpi_device *device)
+static void acpi_processor_post_eject(struct acpi_device *device)
 {
 	struct acpi_processor *pr;
 
@@ -627,7 +627,7 @@ static struct acpi_scan_handler processor_handler = {
 	.ids = processor_device_ids,
 	.attach = acpi_processor_add,
 #ifdef CONFIG_ACPI_HOTPLUG_CPU
-	.detach = acpi_processor_remove,
+	.post_eject = acpi_processor_post_eject,
 #endif
 	.hotplug = {
 		.enabled = true,
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 2c8ba4526278..e4f4542f29af 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -244,18 +244,28 @@ static int acpi_scan_try_to_offline(struct acpi_device *device)
 	return 0;
 }
 
-static int acpi_bus_trim_one(struct acpi_device *adev, void *not_used)
+/**
+ * acpi_bus_trim_one() - Detach scan handlers and drivers from ACPI device
+ *                       objects.
+ * @adev:       Root of the ACPI namespace scope to walk.
+ * @eject:      Pointer to a bool that indicates if this was due to an
+ *              eject-request.
+ *
+ * Must be called under acpi_scan_lock.
+ * If @eject points to true, clearing the device enumeration is deferred until
+ * acpi_bus_post_eject() is called.
+ */
+static int acpi_bus_trim_one(struct acpi_device *adev, void *eject)
 {
 	struct acpi_scan_handler *handler = adev->handler;
+	bool is_eject = *(bool *)eject;
 
-	acpi_dev_for_each_child_reverse(adev, acpi_bus_trim_one, NULL);
+	acpi_dev_for_each_child_reverse(adev, acpi_bus_trim_one, eject);
 
 	adev->flags.match_driver = false;
 	if (handler) {
 		if (handler->detach)
 			handler->detach(adev);
-
-		adev->handler = NULL;
 	} else {
 		device_release_driver(&adev->dev);
 	}
@@ -265,7 +275,12 @@ static int acpi_bus_trim_one(struct acpi_device *adev, void *not_used)
 	 */
 	acpi_device_set_power(adev, ACPI_STATE_D3_COLD);
 	adev->flags.initialized = false;
-	acpi_device_clear_enumerated(adev);
+
+	/* For eject this is deferred to acpi_bus_post_eject() */
+	if (!is_eject) {
+		adev->handler = NULL;
+		acpi_device_clear_enumerated(adev);
+	}
 
 	return 0;
 }
@@ -278,15 +293,36 @@ static int acpi_bus_trim_one(struct acpi_device *adev, void *not_used)
  */
 void acpi_bus_trim(struct acpi_device *adev)
 {
-	acpi_bus_trim_one(adev, NULL);
+	bool eject = false;
+
+	acpi_bus_trim_one(adev, &eject);
 }
 EXPORT_SYMBOL_GPL(acpi_bus_trim);
 
+static int acpi_bus_post_eject(struct acpi_device *adev, void *not_used)
+{
+	struct acpi_scan_handler *handler = adev->handler;
+
+	acpi_dev_for_each_child_reverse(adev, acpi_bus_post_eject, NULL);
+
+	if (handler) {
+		if (handler->post_eject)
+			handler->post_eject(adev);
+
+		adev->handler = NULL;
+	}
+
+	acpi_device_clear_enumerated(adev);
+
+	return 0;
+}
+
 static int acpi_scan_hot_remove(struct acpi_device *device)
 {
 	acpi_handle handle = device->handle;
 	unsigned long long sta;
 	acpi_status status;
+	bool eject = true;
 
 	if (device->handler && device->handler->hotplug.demand_offline) {
 		if (!acpi_scan_is_offline(device, true))
@@ -299,7 +335,7 @@ static int acpi_scan_hot_remove(struct acpi_device *device)
 
 	acpi_handle_debug(handle, "Ejecting\n");
 
-	acpi_bus_trim(device);
+	acpi_bus_trim_one(device, &eject);
 
 	acpi_evaluate_lck(handle, 0);
 	/*
@@ -322,6 +358,8 @@ static int acpi_scan_hot_remove(struct acpi_device *device)
 	} else if (sta & ACPI_STA_DEVICE_ENABLED) {
 		acpi_handle_warn(handle,
 			"Eject incomplete - status 0x%llx\n", sta);
+	} else {
+		acpi_bus_post_eject(device, NULL);
 	}
 
 	return 0;
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index e4d24d3f9abb..436e7e022e4e 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -129,6 +129,7 @@ struct acpi_scan_handler {
 	bool (*match)(const char *idstr, const struct acpi_device_id **matchid);
 	int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id);
 	void (*detach)(struct acpi_device *dev);
+	void (*post_eject)(struct acpi_device *dev);
 	void (*bind)(struct device *phys_dev);
 	void (*unbind)(struct device *phys_dev);
 	struct acpi_hotplug_profile hotplug;
-- 
2.30.2


  parent reply	other threads:[~2024-01-31 16:50 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-31 16:48 [RFC PATCH v4 00/15] ACPI/arm64: add support for virtual cpu hotplug Russell King (Oracle)
2024-01-31 16:49 ` [PATCH RFC v4 01/15] ACPI: Only enumerate enabled (or functional) processor devices Russell King
2024-01-31 17:25   ` Miguel Luis
2024-02-15 20:10   ` Rafael J. Wysocki
2024-02-19  9:45     ` Jonathan Cameron
2024-02-20 11:30     ` Russell King (Oracle)
2024-02-21 13:01   ` Rafael J. Wysocki
2024-01-31 16:49 ` [PATCH RFC v4 02/15] ACPI: processor: Register all CPUs from acpi_processor_get_info() Russell King
2024-02-15 19:22   ` Rafael J. Wysocki
2024-02-20 11:27     ` Russell King (Oracle)
2024-02-20 15:13       ` Russell King (Oracle)
2024-02-20 16:24         ` Jonathan Cameron
2024-02-20 19:59           ` Rafael J. Wysocki
2024-02-21 12:04             ` Rafael J. Wysocki
2024-02-20 20:59     ` Thomas Gleixner
2024-03-22 18:53     ` Jonathan Cameron
2024-04-10 12:43       ` Jonathan Cameron
2024-04-10 13:28         ` Rafael J. Wysocki
2024-04-10 13:50           ` Jonathan Cameron
2024-04-10 14:19             ` Rafael J. Wysocki
2024-04-10 15:58               ` Jonathan Cameron
2024-04-10 18:56             ` Russell King (Oracle)
2024-04-10 19:08               ` Rafael J. Wysocki
2024-04-10 21:07                 ` Jonathan Cameron
2024-01-31 16:49 ` [PATCH RFC v4 03/15] ACPI: Move acpi_bus_trim_one() before acpi_scan_hot_remove() Russell King
2024-01-31 16:49 ` [PATCH RFC v4 04/15] ACPI: Rename acpi_processor_hotadd_init and remove pre-processor guards Russell King
2024-01-31 16:50 ` Russell King [this message]
2024-01-31 16:50 ` [PATCH RFC v4 06/15] ACPI: convert acpi_processor_post_eject() to use IS_ENABLED() Russell King (Oracle)
2024-01-31 16:50 ` [PATCH RFC v4 07/15] ACPI: Check _STA present bit before making CPUs not present Russell King
2024-01-31 16:50 ` [PATCH RFC v4 08/15] ACPI: Warn when the present bit changes but the feature is not enabled Russell King
2024-01-31 16:50 ` [PATCH RFC v4 09/15] arm64: acpi: Move get_cpu_for_acpi_id() to a header Russell King
2024-01-31 16:50 ` [PATCH RFC v4 10/15] irqchip/gic-v3: Don't return errors from gic_acpi_match_gicc() Russell King
2024-02-02 16:44   ` Jonathan Cameron
2024-01-31 16:50 ` [PATCH RFC v4 11/15] irqchip/gic-v3: Add support for ACPI's disabled but 'online capable' CPUs Russell King
2024-02-02 16:47   ` Jonathan Cameron
2024-01-31 16:50 ` [PATCH RFC v4 12/15] arm64: psci: Ignore DENIED CPUs Russell King
2024-04-11 11:35   ` Jonathan Cameron
2024-04-11 13:25     ` Jonathan Cameron
2024-01-31 16:50 ` [PATCH RFC v4 13/15] ACPI: add support to (un)register CPUs based on the _STA enabled bit Russell King
2024-01-31 16:50 ` [PATCH RFC v4 14/15] arm64: document virtual CPU hotplug's expectations Russell King
2024-02-02 17:04   ` Jonathan Cameron
2024-01-31 16:50 ` [PATCH RFC v4 15/15] cpumask: Add enabled cpumask for present CPUs that can be brought online Russell King

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