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-rw-r--r--Documentation/ABI/testing/sysfs-devices-deferred_probe12
-rw-r--r--drivers/base/base.h2
-rw-r--r--drivers/base/core.c7
-rw-r--r--drivers/base/dd.c13
4 files changed, 34 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-deferred_probe b/Documentation/ABI/testing/sysfs-devices-deferred_probe
new file mode 100644
index 000000000000..58553d7a321f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-deferred_probe
@@ -0,0 +1,12 @@
+What: /sys/devices/.../deferred_probe
+Date: August 2016
+Contact: Ben Hutchings <ben.hutchings@codethink.co.uk>
+Description:
+ The /sys/devices/.../deferred_probe attribute is
+ present for all devices. If a driver detects during
+ probing a device that a related device is not yet
+ ready, it may defer probing of the first device. The
+ kernel will retry probing the first device after any
+ other device is successfully probed. This attribute
+ reads as 1 if probing of this device is currently
+ deferred, or 0 otherwise.
diff --git a/drivers/base/base.h b/drivers/base/base.h
index e19b1008e5fb..ada9dce34e6d 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -141,6 +141,8 @@ extern void device_unblock_probing(void);
extern struct kset *devices_kset;
extern void devices_kset_move_last(struct device *dev);
+extern struct device_attribute dev_attr_deferred_probe;
+
#if defined(CONFIG_MODULES) && defined(CONFIG_SYSFS)
extern void module_add_driver(struct module *mod, struct device_driver *drv);
extern void module_remove_driver(struct device_driver *drv);
diff --git a/drivers/base/core.c b/drivers/base/core.c
index d0c9df5cdd9e..b8b2f6105476 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1060,8 +1060,14 @@ static int device_add_attrs(struct device *dev)
goto err_remove_dev_groups;
}
+ error = device_create_file(dev, &dev_attr_deferred_probe);
+ if (error)
+ goto err_remove_online;
+
return 0;
+ err_remove_online:
+ device_remove_file(dev, &dev_attr_online);
err_remove_dev_groups:
device_remove_groups(dev, dev->groups);
err_remove_type_groups:
@@ -1079,6 +1085,7 @@ static void device_remove_attrs(struct device *dev)
struct class *class = dev->class;
const struct device_type *type = dev->type;
+ device_remove_file(dev, &dev_attr_deferred_probe);
device_remove_file(dev, &dev_attr_online);
device_remove_groups(dev, dev->groups);
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 43be1cc751a4..a48cf444eca5 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -53,6 +53,19 @@ static LIST_HEAD(deferred_probe_pending_list);
static LIST_HEAD(deferred_probe_active_list);
static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
+static ssize_t deferred_probe_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ bool value;
+
+ mutex_lock(&deferred_probe_mutex);
+ value = !list_empty(&dev->p->deferred_probe);
+ mutex_unlock(&deferred_probe_mutex);
+
+ return sprintf(buf, "%d\n", value);
+}
+DEVICE_ATTR_RO(deferred_probe);
+
/*
* In some cases, like suspend to RAM or hibernation, It might be reasonable
* to prohibit probing of devices as it could be unsafe.