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 3/5] ACPI: scan: Fix device object rescan in acpi_scan_clear_dep()
Date: Wed, 16 Jun 2021 16:23:44 +0200 [thread overview]
Message-ID: <7272740.EvYhyI6sBW@kreacher> (raw)
In-Reply-To: <3140195.44csPzL39Z@kreacher>
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In general, acpi_bus_attach() can only be run safely under
acpi_scan_lock, but that lock cannot be acquired under
acpi_dep_list_lock, so make acpi_scan_clear_dep() schedule deferred
execution of acpi_bus_attach() under acpi_scan_lock instead of
calling it directly.
This also fixes a possible race between acpi_scan_clear_dep() and
device removal that might cause a device object that went away to
be accessed, because acpi_scan_clear_dep() is changed to acquire
a reference on the consumer device object.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/scan.c | 50 +++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 45 insertions(+), 5 deletions(-)
Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -2115,16 +2115,56 @@ static int acpi_dev_get_first_consumer_d
return 0;
}
-static int acpi_scan_clear_dep(struct acpi_dep_data *dep, void *data)
-{
+struct acpi_scan_clear_dep_work {
+ struct work_struct work;
struct acpi_device *adev;
+};
+
+static void acpi_scan_clear_dep_fn(struct work_struct *work)
+{
+ struct acpi_scan_clear_dep_work *cdw;
+
+ cdw = container_of(work, struct acpi_scan_clear_dep_work, work);
- acpi_bus_get_device(dep->consumer, &adev);
+ acpi_scan_lock_acquire();
+ acpi_bus_attach(cdw->adev, true);
+ acpi_scan_lock_release();
+
+ acpi_dev_put(cdw->adev);
+ kfree(cdw);
+}
+
+static bool acpi_scan_clear_dep_queue(struct acpi_device *adev)
+{
+ struct acpi_scan_clear_dep_work *cdw;
+
+ if (adev->dep_unmet)
+ return false;
+
+ cdw = kmalloc(sizeof(*cdw), GFP_KERNEL);
+ if (!cdw)
+ return false;
+
+ cdw->adev = adev;
+ INIT_WORK(&cdw->work, acpi_scan_clear_dep_fn);
+ /*
+ * Since the work function may block on the lock until the entire
+ * initial enumeration of devices is complete, put it into the unbound
+ * workqueue.
+ */
+ queue_work(system_unbound_wq, &cdw->work);
+
+ return true;
+}
+
+static int acpi_scan_clear_dep(struct acpi_dep_data *dep, void *data)
+{
+ struct acpi_device *adev = acpi_bus_get_acpi_device(dep->consumer);
if (adev) {
adev->dep_unmet--;
- if (!adev->dep_unmet)
- acpi_bus_attach(adev, true);
+ if (!acpi_scan_clear_dep_queue(adev))
+ acpi_dev_put(adev);
}
list_del(&dep->node);
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 ` Rafael J. Wysocki [this message]
2021-06-16 14:48 ` [PATCH 3/5] ACPI: scan: Fix device object rescan in acpi_scan_clear_dep() 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 ` [PATCH 5/5] ACPI: scan: Fix race related to dropping dependencies Rafael J. Wysocki
2021-06-16 14:55 ` 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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