From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux ACPI <linux-acpi@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Hans de Goede <hdegoede@redhat.com>
Subject: [PATCH 5/5] ACPI: scan: Fix race related to dropping dependencies
Date: Wed, 16 Jun 2021 16:25:32 +0200 [thread overview]
Message-ID: <3070024.5fSG56mABF@kreacher> (raw)
In-Reply-To: <3140195.44csPzL39Z@kreacher>
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
If acpi_add_single_object() runs concurrently with respect to
acpi_scan_clear_dep() which deletes a dependencies list entry where
the device being added is the consumer, the device's dep_unmet
counter may not be updated to reflect that change.
Namely, if the dependencies list entry is deleted right after
calling acpi_scan_dep_init() and before calling acpi_device_add(),
acpi_scan_clear_dep() will not find the device object corresponding
to the consumer device ACPI handle and it will not update its
dep_unmet counter to reflect the deletion of the list entry.
Consequently, the dep_unmet counter of the device will never
become zero going forward which may prevent it from being
completely enumerated.
To address this problem, modify acpi_add_single_object() to run
acpi_tie_acpi_dev(), to attach the ACPI device object created by it
to the corresponding ACPI namespace node, under acpi_dep_list_lock
along with acpi_scan_dep_init() whenever the latter is called.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/scan.c | 46 +++++++++++++++++++++++++++++++++-------------
1 file changed, 33 insertions(+), 13 deletions(-)
Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -657,16 +657,12 @@ static int acpi_tie_acpi_dev(struct acpi
return 0;
}
-int acpi_device_add(struct acpi_device *device,
- void (*release)(struct device *))
+int __acpi_device_add(struct acpi_device *device,
+ void (*release)(struct device *))
{
struct acpi_device_bus_id *acpi_device_bus_id;
int result;
- result = acpi_tie_acpi_dev(device);
- if (result)
- return result;
-
/*
* Linkage
* -------
@@ -755,6 +751,17 @@ err_unlock:
return result;
}
+int acpi_device_add(struct acpi_device *adev, void (*release)(struct device *))
+{
+ int ret;
+
+ ret = acpi_tie_acpi_dev(adev);
+ if (ret)
+ return ret;
+
+ return __acpi_device_add(adev, release);
+}
+
/* --------------------------------------------------------------------------
Device Enumeration
-------------------------------------------------------------------------- */
@@ -1681,14 +1688,10 @@ static void acpi_scan_dep_init(struct ac
{
struct acpi_dep_data *dep;
- mutex_lock(&acpi_dep_list_lock);
-
list_for_each_entry(dep, &acpi_dep_list, node) {
if (dep->consumer == adev->handle)
adev->dep_unmet++;
}
-
- mutex_unlock(&acpi_dep_list_lock);
}
void acpi_device_add_finalize(struct acpi_device *device)
@@ -1707,6 +1710,7 @@ static int acpi_add_single_object(struct
acpi_handle handle, int type, bool dep_init)
{
struct acpi_device *device;
+ bool release_dep_lock = false;
int result;
device = kzalloc(sizeof(struct acpi_device), GFP_KERNEL);
@@ -1720,16 +1724,32 @@ static int acpi_add_single_object(struct
* this must be done before the get power-/wakeup_dev-flags calls.
*/
if (type == ACPI_BUS_TYPE_DEVICE || type == ACPI_BUS_TYPE_PROCESSOR) {
- if (dep_init)
+ if (dep_init) {
+ mutex_lock(&acpi_dep_list_lock);
+ /*
+ * Hold the lock until the acpi_tie_acpi_dev() call
+ * below to prevent concurrent acpi_scan_clear_dep()
+ * from deleting a dependency list entry without
+ * updating dep_unmet for the device.
+ */
+ release_dep_lock = true;
acpi_scan_dep_init(device);
-
+ }
acpi_scan_init_status(device);
}
acpi_bus_get_power_flags(device);
acpi_bus_get_wakeup_device_flags(device);
- result = acpi_device_add(device, acpi_device_release);
+ result = acpi_tie_acpi_dev(device);
+
+ if (release_dep_lock)
+ mutex_unlock(&acpi_dep_list_lock);
+
+ if (result)
+ return result;
+
+ result = __acpi_device_add(device, acpi_device_release);
if (result) {
acpi_device_release(&device->dev);
return result;
next prev parent reply other threads:[~2021-06-16 14:26 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 14:21 [PATCH 0/5] ACPI: scan: Fixes and cleanups related to dependencies list handling Rafael J. Wysocki
2021-06-16 14:21 ` [PATCH 1/5] ACPI: scan: Rearrange acpi_dev_get_first_consumer_dev_cb() Rafael J. Wysocki
2021-06-16 14:36 ` Hans de Goede
2021-06-16 14:22 ` [PATCH 2/5] ACPI: scan: Make acpi_walk_dep_device_list() Rafael J. Wysocki
2021-06-16 14:41 ` Hans de Goede
2021-06-16 15:11 ` Rafael J. Wysocki
2021-06-16 15:25 ` Rafael J. Wysocki
2021-06-16 15:28 ` Hans de Goede
2021-06-16 14:23 ` [PATCH 3/5] ACPI: scan: Fix device object rescan in acpi_scan_clear_dep() Rafael J. Wysocki
2021-06-16 14:48 ` Hans de Goede
2021-06-16 15:12 ` Rafael J. Wysocki
2021-06-16 14:24 ` [PATCH 4/5] ACPI: scan: Reorganize acpi_device_add() Rafael J. Wysocki
2021-06-16 14:49 ` Hans de Goede
2021-06-16 14:25 ` Rafael J. Wysocki [this message]
2021-06-16 14:55 ` [PATCH 5/5] ACPI: scan: Fix race related to dropping dependencies Hans de Goede
2021-06-16 15:19 ` Rafael J. Wysocki
2021-06-16 18:00 ` [PATCH v2 " Rafael J. Wysocki
2021-06-16 18:04 ` Hans de Goede
2021-06-17 0:25 ` [PATCH " kernel test robot
2021-06-17 0:41 ` kernel test robot
2021-06-17 0:42 ` [RFC PATCH] ACPI: scan: __acpi_device_add() can be static kernel test robot
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