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Date: Fri, 12 Jul 2019 16:52:38 -0700
From: Saravana Kannan <saravanak@...gle.com>
To: Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Frank Rowand <frowand.list@...il.com>
Cc: Saravana Kannan <saravanak@...gle.com>, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org,
David Collins <collinsd@...eaurora.org>,
kernel-team@...roid.com
Subject: [PATCH v5 05/11] driver core: Add APIs to pause/resume sync state callbacks
When multiple devices are added after kernel init, some suppliers could be
added before their consumer devices get added. In these instances, the
supplier devices could get their sync_state callback called right after
they probe because the consumers haven't had a chance to create device
links to the suppliers.
This change adds APIs to pause/resume sync state callbacks so that when
multiple devices are added, their sync_state callback evaluation can be
postponed to happen after all of them are added.
Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
drivers/base/core.c | 40 +++++++++++++++++++++++++++++++++-------
drivers/of/platform.c | 5 ++---
include/linux/device.h | 6 ++++--
3 files changed, 39 insertions(+), 12 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index dce97b5f3536..b03e679faea4 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -46,7 +46,8 @@ early_param("sysfs.deprecated", sysfs_deprecated_setup);
/* Device links support. */
static LIST_HEAD(wait_for_suppliers);
static DEFINE_MUTEX(wfs_lock);
-static bool supplier_sync_state_enabled;
+static LIST_HEAD(deferred_sync);
+static unsigned int supplier_sync_state_disabled;
#ifdef CONFIG_SRCU
static DEFINE_MUTEX(device_links_lock);
@@ -657,17 +658,38 @@ static void __device_links_supplier_sync_state(struct device *dev)
dev->state_synced = true;
}
-int device_links_supplier_sync_state(struct device *dev, void *data)
+void device_links_supplier_sync_state_pause(void)
{
device_links_write_lock();
- __device_links_supplier_sync_state(dev);
+ supplier_sync_state_disabled++;
device_links_write_unlock();
- return 0;
}
-void device_links_supplier_sync_state_enable(void)
+void device_links_supplier_sync_state_resume(void)
{
- supplier_sync_state_enabled = true;
+ struct device *dev, *tmp;
+
+ device_links_write_lock();
+ if (!supplier_sync_state_disabled) {
+ WARN(true, "Unmatched sync_state pause/resume!");
+ goto out;
+ }
+ supplier_sync_state_disabled--;
+ if (supplier_sync_state_disabled)
+ goto out;
+
+ list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_sync) {
+ __device_links_supplier_sync_state(dev);
+ list_del_init(&dev->links.defer_sync);
+ }
+out:
+ device_links_write_unlock();
+}
+
+static void __device_links_supplier_defer_sync(struct device *sup)
+{
+ if (list_empty(&sup->links.defer_sync))
+ list_add_tail(&sup->links.defer_sync, &deferred_sync);
}
/**
@@ -715,7 +737,9 @@ void device_links_driver_bound(struct device *dev)
WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
WRITE_ONCE(link->status, DL_STATE_ACTIVE);
- if (supplier_sync_state_enabled)
+ if (supplier_sync_state_disabled)
+ __device_links_supplier_defer_sync(link->supplier);
+ else
__device_links_supplier_sync_state(link->supplier);
}
@@ -826,6 +850,7 @@ void device_links_driver_cleanup(struct device *dev)
WRITE_ONCE(link->status, DL_STATE_DORMANT);
}
+ list_del_init(&dev->links.defer_sync);
__device_links_no_driver(dev);
device_links_write_unlock();
@@ -1797,6 +1822,7 @@ void device_initialize(struct device *dev)
INIT_LIST_HEAD(&dev->links.consumers);
INIT_LIST_HEAD(&dev->links.suppliers);
INIT_LIST_HEAD(&dev->links.needs_suppliers);
+ INIT_LIST_HEAD(&dev->links.defer_sync);
dev->links.status = DL_DEV_NO_DRIVER;
}
EXPORT_SYMBOL_GPL(device_initialize);
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 4d12d6658999..56b718f09929 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -581,6 +581,7 @@ static int __init of_platform_default_populate_init(void)
return -ENODEV;
platform_bus_type.add_links = of_link_to_suppliers;
+ device_links_supplier_sync_state_pause();
/*
* Handle certain compatibles explicitly, since we don't want to create
* platform_devices for every node in /reserved-memory with a
@@ -604,9 +605,7 @@ arch_initcall_sync(of_platform_default_populate_init);
static int __init of_platform_sync_state_init(void)
{
- device_links_supplier_sync_state_enable();
- bus_for_each_dev(&platform_bus_type, NULL, NULL,
- device_links_supplier_sync_state);
+ device_links_supplier_sync_state_resume();
return 0;
}
late_initcall_sync(of_platform_sync_state_init);
diff --git a/include/linux/device.h b/include/linux/device.h
index d3c9e70052d8..0ea28cb8c77e 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -926,12 +926,14 @@ enum dl_dev_state {
* @suppliers: List of links to supplier devices.
* @consumers: List of links to consumer devices.
* @needs_suppliers: Hook to global list of devices waiting for suppliers.
+ * @defer_sync: Hook to global list of devices that have deferred sync_state.
* @status: Driver status information.
*/
struct dev_links_info {
struct list_head suppliers;
struct list_head consumers;
struct list_head needs_suppliers;
+ struct list_head defer_sync;
enum dl_dev_state status;
};
@@ -1438,8 +1440,8 @@ struct device_link *device_link_add(struct device *consumer,
struct device *supplier, u32 flags);
void device_link_del(struct device_link *link);
void device_link_remove(void *consumer, struct device *supplier);
-int device_links_supplier_sync_state(struct device *dev, void *data);
-void device_links_supplier_sync_state_enable(void);
+void device_links_supplier_sync_state_pause(void);
+void device_links_supplier_sync_state_resume(void);
void device_link_remove_from_wfs(struct device *consumer);
#ifndef dev_fmt
--
2.22.0.510.g264f2c817a-goog
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