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@xxxxxxxxxx>
---
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
