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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: ACPI Devel Maling List <linux-acpi@vger.kernel.org>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Aaron Lu <aaron.lu@intel.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux PCI <linux-pci@vger.kernel.org>
Subject: [PATCH 5/24][New] ACPI / hotplug / PCI: Fix bridge removal race vs dock events
Date: Tue, 04 Feb 2014 00:18:57 +0100	[thread overview]
Message-ID: <1844787.IDye8ayOzv@vostro.rjw.lan> (raw)
In-Reply-To: <7532948.aJNUotNMpR@vostro.rjw.lan>

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

If a PCI bridge with an ACPIPHP context attached is removed via
sysfs, the code path executed as a result is the following:

pci_stop_and_remove_bus_device_locked
 pci_remove_bus
  pcibios_remove_bus
   acpi_pci_remove_bus
    acpiphp_remove_slots
     cleanup_bridge
      unregister_hotplug_dock_device (drops dock references to the bridge)
     put_bridge
      free_bridge
       acpiphp_put_context (for each child, under context lock)
        kfree (context)

Now, if a dock event affecting one of the bridge's child devices
occurs (roughly at the same time), it will lead to the following code
path:

acpi_dock_deferred_cb
 dock_notify
  handle_eject_request
   hot_remove_dock_devices
    dock_hotplug_event
     hotplug_event (dereferences context)

That may lead to a kernel crash in hotplug_event() if it is executed
after the last kfree() in the bridge removal code path.

To prevent that from happening, add a wrapper around hotplug_event()
called dock_event() and point the .handler pointer in acpiphp_dock_ops
to it.  Make that wrapper retrieve the device's ACPIPHP context using
acpiphp_get_context() (instead of taking it from the data argument)
under acpiphp_context_lock and check if the parent bridge's
is_going_away flag is set.  If that flag is set, it will return
immediately and if it is not set it will grab a reference to the
device's parent bridge before executing hotplug_event().

Then, in the above scenario, the reference to the parent bridge
held by dock_event() will prevent free_bridge() from being executed
for it until hotplug_event() returns.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/pci/hotplug/acpiphp_glue.c |   21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

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
@@ -210,10 +210,29 @@ static void post_dock_fixups(acpi_handle
 	}
 }
 
+static void dock_event(acpi_handle handle, u32 type, void *data)
+{
+	struct acpiphp_context *context;
+
+	mutex_lock(&acpiphp_context_lock);
+	context = acpiphp_get_context(handle);
+	if (!context || WARN_ON(context->handle != handle)
+	    || context->func.parent->is_going_away) {
+		mutex_unlock(&acpiphp_context_lock);
+		return;
+	}
+	get_bridge(context->func.parent);
+	acpiphp_put_context(context);
+	mutex_unlock(&acpiphp_context_lock);
+
+	hotplug_event(handle, type, data);
+
+	put_bridge(context->func.parent);
+}
 
 static const struct acpi_dock_ops acpiphp_dock_ops = {
 	.fixup = post_dock_fixups,
-	.handler = hotplug_event,
+	.handler = dock_event,
 };
 
 /* Check whether the PCI device is managed by native PCIe hotplug driver */


  parent reply	other threads:[~2014-02-03 23:30 UTC|newest]

Thread overview: 100+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-27  0:37 [PATCH 0/11] ACPI / hotplug / PCI: Updates on top of changes merged recently Rafael J. Wysocki
2014-01-27  0:38 ` [PATCH 1/11] ACPI / hotplug / PCI: Proper kerneldoc comments for enumeration/removal Rafael J. Wysocki
2014-01-27  0:38 ` [PATCH 2/11] ACPI / hotplug / PCI: Simplify register_slot() Rafael J. Wysocki
2014-01-27  0:39 ` [PATCH 3/11] ACPI / hotplug / PCI: Drop acpiphp_bus_trim() Rafael J. Wysocki
2014-01-27  0:40 ` [PATCH 4/11] ACPI / hotplug / PCI: Rework acpiphp_no_hotplug() Rafael J. Wysocki
2014-01-27  0:41 ` [PATCH 5/11] ACPI / hotplug / PCI: Store acpi_device pointer in acpiphp_context Rafael J. Wysocki
2014-01-27  0:41 ` [PATCH 6/11] ACPI / hotplug / PCI: Drop acpiphp_bus_add() Rafael J. Wysocki
2014-01-27  0:42 ` [PATCH 7/11] ACPI / hotplug / PCI: Drop crit_sect locking Rafael J. Wysocki
2014-01-27  0:43 ` [PATCH 8/11] ACPI / hotplug / PCI: Simplify hotplug_event() Rafael J. Wysocki
2014-01-27  0:44 ` [PATCH 9/11] ACPI / hotplug / PCI: Simplify disable_slot() Rafael J. Wysocki
2014-01-27  0:45 ` [PATCH 10/11] ACPI / hotplug / PCI: Use acpi_handle_debug() in hotplug_event() Rafael J. Wysocki
2014-01-27  0:46 ` [PATCH 11/11] ACPI / hotplug: Do not pass ACPI handles to ACPI dock operations Rafael J. Wysocki
2014-01-28 22:10 ` [PATCH 0/5][RFT] ACPI / hotplug / PCI: Consolidation of ACPIPHP with ACPI core device hotplug Rafael J. Wysocki
2014-01-28 22:12   ` [PATCH 1/5][RFT] ACPI / hotplug / PCI: Attach hotplug contexts to struct acpi_device Rafael J. Wysocki
2014-01-28 22:13   ` [PATCH 2/5][RFT] ACPI / hotplug: Introduce acpi_install_hotplug_notify_handler() Rafael J. Wysocki
2014-01-28 22:14   ` [PATCH 3/5][RFT] ACPI / hotplug / PCI: Consolidate ACPIPHP with ACPI core hotplug Rafael J. Wysocki
2014-01-28 22:14   ` [PATCH 4/5][RFT] ACPI / hotplug / PCI: Simplify acpi_install_hotplug_notify_handler() Rafael J. Wysocki
2014-01-28 22:16   ` [PATCH 5/5][RFT] ACPI / hotplug: Dispach hotplug notifications from acpi_bus_notify() Rafael J. Wysocki
2014-01-28 23:57   ` [PATCH 0/5][RFT] ACPI / hotplug / PCI: Consolidation of ACPIPHP with ACPI core device hotplug Rafael J. Wysocki
2014-01-28 23:58     ` [Resend][PATCH 1/5][RFT] ACPI / hotplug / PCI: Attach hotplug contexts to struct acpi_device Rafael J. Wysocki
2014-01-28 23:59     ` [Resend][PATCH 2/5][RFT] ACPI / hotplug: Introduce acpi_install_hotplug_notify_handler() Rafael J. Wysocki
2014-01-28 23:59     ` [Update][PATCH 3/5][RFT] ACPI / hotplug / PCI: Consolidate ACPIPHP with ACPI core hotplug Rafael J. Wysocki
2014-01-29  0:00     ` [Update][PATCH 4/5][RFT] ACPI / hotplug / PCI: Simplify acpi_install_hotplug_notify_handler() Rafael J. Wysocki
2014-01-31 15:28       ` Mika Westerberg
2014-01-31 15:42         ` Rafael J. Wysocki
2014-01-31 15:40           ` Mika Westerberg
2014-01-31 16:01             ` Mika Westerberg
2014-01-31 16:16               ` Rafael J. Wysocki
2014-01-31 17:09                 ` Mika Westerberg
2014-01-31 17:34                   ` Rafael J. Wysocki
2014-02-02  0:12                     ` Rafael J. Wysocki
2014-01-29  0:02     ` [Update][PATCH 5/5][RFT] ACPI / hotplug / PCI: Hotplug notifications from acpi_bus_notify() Rafael J. Wysocki
2014-01-30 15:28       ` [Update 2x][PATCH " Rafael J. Wysocki
2014-02-02  0:52     ` [PATCH v2 0/6] ACPI / hotplug / PCI: Consolidation of ACPIPHP with ACPI core device hotplug Rafael J. Wysocki
2014-02-02  0:54       ` [PATCH v2 1/6] ACPI / hotplug: Fix theoretical race in acpi_hotplug_notify_cb() Rafael J. Wysocki
2014-02-02 17:01         ` Rafael J. Wysocki
2014-02-02  0:55       ` [PATCH v2 2/6] ACPI / hotplug / PCI: Define hotplug context lock in the core Rafael J. Wysocki
2014-02-02  0:56       ` [PATCH v2 3/6] ACPI / hotplug / PCI: Consolidate ACPIPHP with ACPI core hotplug Rafael J. Wysocki
2014-02-02  0:57       ` [PATCH v2 4/6] ACPI / hotplug / PCI: Rework the handling of eject requests Rafael J. Wysocki
2014-02-02  0:58       ` [PATCH v2 5/6] ACPI / hotplug / PCI: Simplify acpi_install_hotplug_notify_handler() Rafael J. Wysocki
2014-02-02  0:58       ` [PATCH v2 6/6] ACPI / hotplug / PCI: Hotplug notifications from acpi_bus_notify() Rafael J. Wysocki
2014-02-02 17:11       ` [PATCH v3 0/7] ACPI / hotplug / PCI: Consolidation of ACPIPHP with ACPI core device hotplug Rafael J. Wysocki
2014-02-02 17:12         ` [PATCH v3 1/7] ACPICA: Introduce acpi_get_data_full() and rework acpi_get_data() Rafael J. Wysocki
2014-02-02 17:15         ` [PATCH v3 2/7] ACPI / hotplug: Fix potential races in notify handlers Rafael J. Wysocki
2014-02-02 17:16         ` [PATCH v3 3/7] ACPI / hotplug / PCI: Define hotplug context lock in the core Rafael J. Wysocki
2014-02-02 17:17         ` [PATCH v3 4/7] ACPI / hotplug / PCI: Consolidate ACPIPHP with ACPI core hotplug Rafael J. Wysocki
2014-02-02 17:18         ` [PATCH v3 5/7] ACPI / hotplug / PCI: Rework the handling of eject requests Rafael J. Wysocki
2014-02-02 17:19         ` [PATCH v3 6/7] ACPI / hotplug / PCI: Simplify acpi_install_hotplug_notify_handler() Rafael J. Wysocki
2014-02-02 17:20         ` [PATCH v3 7/7] ACPI / hotplug / PCI: Hotplug notifications from acpi_bus_notify() Rafael J. Wysocki
2014-02-03 10:45         ` [PATCH v3 0/7] ACPI / hotplug / PCI: Consolidation of ACPIPHP with ACPI core device hotplug Mika Westerberg
2014-02-03 21:51           ` Rafael J. Wysocki
2014-02-02  0:19 ` [PATCH v2 0/13] ACPI / hotplug / PCI: Updates on top of changes merged recently Rafael J. Wysocki
2014-02-02  0:21   ` [PATCH v2 1/13] ACPI / hotplug / PCI: Remove entries from bus->devices in reverse order Rafael J. Wysocki
2014-02-02  0:22   ` [PATCH v2 2/13] ACPI / hotplug / PCI: Move PCI rescan-remove locking to hotplug_event() Rafael J. Wysocki
2014-02-02  0:23   ` [PATCH v2 3/13] ACPI / hotplug / PCI: Simplify disable_slot() Rafael J. Wysocki
2014-02-02  0:24   ` [PATCH v2 4/13] ACPI / hotplug / PCI: Proper kerneldoc comments for enumeration/removal Rafael J. Wysocki
2014-02-02  0:25   ` [PATCH v2 5/13] ACPI / hotplug / PCI: Simplify register_slot() Rafael J. Wysocki
2014-02-02  0:26   ` [PATCH v2 6/13] ACPI / hotplug / PCI: Drop acpiphp_bus_trim() Rafael J. Wysocki
2014-02-02  0:27   ` [PATCH v2 7/13] ACPI / hotplug / PCI: Rework acpiphp_no_hotplug() Rafael J. Wysocki
2014-02-02  0:27   ` [PATCH v2 8/13] ACPI / hotplug / PCI: Store acpi_device pointer in acpiphp_context Rafael J. Wysocki
2014-02-02  0:28   ` [PATCH v2 9/13] ACPI / hotplug / PCI: Drop acpiphp_bus_add() Rafael J. Wysocki
2014-02-02  0:29   ` [PATCH v2 10/13] ACPI / hotplug / PCI: Drop crit_sect locking Rafael J. Wysocki
2014-02-02  0:30   ` [PATCH v2 11/13] ACPI / hotplug / PCI: Simplify hotplug_event() Rafael J. Wysocki
2014-02-02  0:31   ` [PATCH v2 12/13] ACPI / hotplug / PCI: Use acpi_handle_debug() in hotplug_event() Rafael J. Wysocki
2014-02-02  0:31   ` [PATCH v2 13/13] ACPI / hotplug: Do not pass ACPI handles to ACPI dock operations Rafael J. Wysocki
2014-02-03  1:47   ` [PATCH] ACPI / hotplug / PCI: Scan root bus under the PCI rescan-remove lock Rafael J. Wysocki
2014-02-03 10:44   ` [PATCH v2 0/13] ACPI / hotplug / PCI: Updates on top of changes merged recently Mika Westerberg
2014-02-03 23:12     ` [PATCH v2 0/24] ACPI / hotplug / PCI: ACPIPHP updates and consolidation with ACPI core Rafael J. Wysocki
2014-02-03 23:14       ` [PATCH 1/24][Resend] ACPI / hotplug / PCI: Remove entries from bus->devices in reverse order Rafael J. Wysocki
2014-02-03 23:15       ` [PATCH 2/24][Resend] ACPI / hotplug / PCI: Move PCI rescan-remove locking to hotplug_event() Rafael J. Wysocki
2014-02-03 23:16       ` [PATCH 3/24][Resend] ACPI / hotplug / PCI: Scan root bus under the PCI rescan-remove lock Rafael J. Wysocki
2014-02-03 23:18       ` [PATCH 4/24][New] ACPI / hotplug / PCI: Fix bridge removal race in handle_hotplug_event() Rafael J. Wysocki
2014-02-03 23:18       ` Rafael J. Wysocki [this message]
2014-02-03 23:20       ` [PATCH 6/24][Resend] ACPI / hotplug / PCI: Simplify disable_slot() Rafael J. Wysocki
2014-02-03 23:21       ` [PATCH 7/24][Resend] ACPI / hotplug / PCI: Proper kerneldoc comments for enumeration/removal Rafael J. Wysocki
2014-02-03 23:22       ` [PATCH 8/24][Resend] ACPI / hotplug / PCI: Simplify register_slot() Rafael J. Wysocki
2014-02-03 23:23       ` [PATCH 9/24][Resend] ACPI / hotplug / PCI: Drop acpiphp_bus_trim() Rafael J. Wysocki
2014-02-03 23:24       ` [PATCH 10/24][Resend] ACPI / hotplug / PCI: Rework acpiphp_no_hotplug() Rafael J. Wysocki
2014-02-03 23:25       ` [PATCH 11/24][Update] ACPI / hotplug / PCI: Store acpi_device pointer in acpiphp_context Rafael J. Wysocki
2014-02-03 23:26       ` [PATCH 12/24][Resend] ACPI / hotplug / PCI: Drop acpiphp_bus_add() Rafael J. Wysocki
2014-02-03 23:27       ` [PATCH 13/24][Resend] ACPI / hotplug / PCI: Drop crit_sect locking Rafael J. Wysocki
2014-02-03 23:33       ` [PATCH 14/24][Update] ACPI / hotplug / PCI: Simplify hotplug_event() Rafael J. Wysocki
2014-02-03 23:33       ` [PATCH 15/24][Resend] ACPI / hotplug / PCI: Use acpi_handle_debug() in hotplug_event() Rafael J. Wysocki
2014-02-03 23:34       ` [PATCH 16/24][New] ACPI / hotplug / PCI: Do not pass ACPI handle to hotplug_event() Rafael J. Wysocki
2014-02-03 23:34       ` [PATCH 17/24][Resend] ACPICA: Introduce acpi_get_data_full() and rework acpi_get_data() Rafael J. Wysocki
2014-02-03 23:36       ` [PATCH 18/24][Update] ACPI / hotplug: Fix potential race in acpi_bus_notify() Rafael J. Wysocki
2014-02-03 23:36       ` [PATCH 19/24][Update] ACPI / hotplug / PCI: Define hotplug context lock in the core Rafael J. Wysocki
2014-02-03 23:37       ` [PATCH 20/24][Update] ACPI / hotplug / PCI: Consolidate ACPIPHP with ACPI core hotplug Rafael J. Wysocki
2014-02-06 13:07         ` [Update][PATCH 20/24] " Rafael J. Wysocki
2014-02-06 23:35           ` [Update 2x][PATCH " Rafael J. Wysocki
2014-02-03 23:38       ` [PATCH 21/24][Resend] ACPI / hotplug / PCI: Rework the handling of eject requests Rafael J. Wysocki
2014-02-03 23:39       ` [PATCH 22/24][Resend] ACPI / hotplug / PCI: Simplify acpi_install_hotplug_notify_handler() Rafael J. Wysocki
2014-02-06 13:09         ` [Update][PATCH 22/24] " Rafael J. Wysocki
2014-02-03 23:40       ` [PATCH 23/24][Update] ACPI / hotplug / PCI: Hotplug notifications from acpi_bus_notify() Rafael J. Wysocki
2014-02-06 13:10         ` [Update][PATCH 23/24] " Rafael J. Wysocki
2014-02-03 23:41       ` [PATCH 24/24][New] ACPI / hotplug / PCI: Rework acpiphp_check_host_bridge() Rafael J. Wysocki
2014-02-05 10:14       ` [PATCH v2 0/24] ACPI / hotplug / PCI: ACPIPHP updates and consolidation with ACPI core Mika Westerberg
2014-02-05 10:59         ` Rafael J. Wysocki
2014-02-11  0:19 ` [PATCH 0/11] ACPI / hotplug / PCI: Updates on top of changes merged recently Bjorn Helgaas
2014-02-11 12:53   ` Rafael J. Wysocki

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