linux-kernel - [RFC][PATCH 22/30] ACPI / hotplug / PCI: Do not queue up event handling work items in vain

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Date:	Fri, 12 Jul 2013 02:00:46 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Yinghai Lu <yinghai@...nel.org>, Jiang Liu <liuj97@...il.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [RFC][PATCH 22/30] ACPI / hotplug / PCI: Do not queue up event handling work items in vain

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Modify handle_hotplug_event() to avoid queing up the execution of
handle_hotplug_event_work_fn() as a work item on kacpi_hotplug_wq
for non-hotplug events, such as ACPI_NOTIFY_DEVICE_WAKE.  Move
the code printing diagnostic messages for those events into
handle_hotplug_event().

In addition to that, remove the bogus comment about how the core
should distinguish between hotplug and non-hotplug events and
queue them up on different workqueues.  The core clearly cannot
know in advance what events will be interesting to the given
caller of acpi_install_notify_handler().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/pci/hotplug/acpiphp_glue.c |   64 ++++++++++++++++---------------------
 1 file changed, 29 insertions(+), 35 deletions(-)

Index: linux-pm/drivers/pci/hotplug/acpiphp_glue.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/acpiphp_glue.c
+++ linux-pm/drivers/pci/hotplug/acpiphp_glue.c
@@ -932,36 +932,11 @@ static void hotplug_event(acpi_handle ha
 
 		break;
 
-	case ACPI_NOTIFY_DEVICE_WAKE:
-		/* wake event */
-		dbg("%s: Device wake notify on %s\n", __func__, objname);
-		break;
-
 	case ACPI_NOTIFY_EJECT_REQUEST:
 		/* request device eject */
 		dbg("%s: Device eject notify on %s\n", __func__, objname);
 		acpiphp_disable_and_eject_slot(func->slot);
 		break;
-
-	case ACPI_NOTIFY_FREQUENCY_MISMATCH:
-		printk(KERN_ERR "Device %s cannot be configured due"
-				" to a frequency mismatch\n", objname);
-		break;
-
-	case ACPI_NOTIFY_BUS_MODE_MISMATCH:
-		printk(KERN_ERR "Device %s cannot be configured due"
-				" to a bus mode mismatch\n", objname);
-		break;
-
-	case ACPI_NOTIFY_POWER_FAULT:
-		printk(KERN_ERR "Device %s has suffered a power fault\n",
-				objname);
-		break;
-
-	default:
-		warn("notify_handler: unknown event type 0x%x for %s\n", type,
-		     objname);
-		break;
 	}
 
 	if (bridge)
@@ -996,23 +971,42 @@ static void handle_hotplug_event(acpi_ha
 {
 	struct acpiphp_context *context;
 
+	switch (type) {
+	case ACPI_NOTIFY_BUS_CHECK:
+	case ACPI_NOTIFY_DEVICE_CHECK:
+	case ACPI_NOTIFY_EJECT_REQUEST:
+		break;
+
+	case ACPI_NOTIFY_DEVICE_WAKE:
+		return;
+
+	case ACPI_NOTIFY_FREQUENCY_MISMATCH:
+		acpi_handle_err(handle, "Device cannot be configured due "
+				"to a frequency mismatch\n");
+		return;
+
+	case ACPI_NOTIFY_BUS_MODE_MISMATCH:
+		acpi_handle_err(handle, "Device cannot be configured due "
+				"to a bus mode mismatch\n");
+		return;
+
+	case ACPI_NOTIFY_POWER_FAULT:
+		acpi_handle_err(handle, "Device has suffered a power fault\n");
+		return;
+
+	default:
+		acpi_handle_warn(handle, "Unsupported event type 0x%x\n", type);
+		return;
+	}
+
 	mutex_lock(&acpiphp_context_lock);
 	context = acpiphp_get_context(handle);
 	if (context) {
 		get_bridge(context->func.parent);
 		acpiphp_put_context(context);
+		alloc_acpi_hp_work(handle, type, context, hotplug_event_work);
 	}
 	mutex_unlock(&acpiphp_context_lock);
-	/*
-	 * Currently the code adds all hotplug events to the kacpid_wq
-	 * queue when it should add hotplug events to the kacpi_hotplug_wq.
-	 * The proper way to fix this is to reorganize the code so that
-	 * drivers (dock, etc.) do not call acpi_os_execute(), etc.
-	 * For now just re-add this work to the kacpi_hotplug_wq so we
-	 * don't deadlock on hotplug actions.
-	 */
-	if (context)
-		alloc_acpi_hp_work(handle, type, context, hotplug_event_work);
 }
 
 /*

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