[PATCH AUTOSEL 4.14 071/170] kobject: return error code if writing /sys/.../uevent fails

[Sasha Levin <sashal@xxxxxxxxxx>]

From: Peter Rajnoha <prajnoha@xxxxxxxxxx>

[ Upstream commit df44b479654f62b478c18ee4d8bc4e9f897a9844 ]

Propagate error code back to userspace if writing the /sys/.../uevent
file fails. Before, the write operation always returned with success,
even if we failed to recognize the input string or if we failed to
generate the uevent itself.

With the error codes properly propagated back to userspace, we are
able to react in userspace accordingly by not assuming and awaiting
a uevent that is not delivered.

Signed-off-by: Peter Rajnoha <prajnoha@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/base/bus.c  | 12 ++++++++----
 drivers/base/core.c |  8 +++++++-
 kernel/module.c     |  6 ++++--
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 1cf1460f8c90..3464c49dad0d 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -616,8 +616,10 @@ static void remove_probe_files(struct bus_type *bus)
 static ssize_t uevent_store(struct device_driver *drv, const char *buf,
 			    size_t count)
 {
-	kobject_synth_uevent(&drv->p->kobj, buf, count);
-	return count;
+	int rc;
+
+	rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
+	return rc ? rc : count;
 }
 static DRIVER_ATTR_WO(uevent);
 
@@ -833,8 +835,10 @@ static void klist_devices_put(struct klist_node *n)
 static ssize_t bus_uevent_store(struct bus_type *bus,
 				const char *buf, size_t count)
 {
-	kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
-	return count;
+	int rc;
+
+	rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
+	return rc ? rc : count;
 }
 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
 
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 3f463a61f8cf..d0c67512854c 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -991,8 +991,14 @@ static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,
 static ssize_t uevent_store(struct device *dev, struct device_attribute *attr,
 			    const char *buf, size_t count)
 {
-	if (kobject_synth_uevent(&dev->kobj, buf, count))
+	int rc;
+
+	rc = kobject_synth_uevent(&dev->kobj, buf, count);
+
+	if (rc) {
 		dev_err(dev, "uevent: failed to send synthetic uevent\n");
+		return rc;
+	}
 
 	return count;
 }
diff --git a/kernel/module.c b/kernel/module.c
index 2a44c515f0d7..94528b891027 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1201,8 +1201,10 @@ static ssize_t store_uevent(struct module_attribute *mattr,
 			    struct module_kobject *mk,
 			    const char *buffer, size_t count)
 {
-	kobject_synth_uevent(&mk->kobj, buffer, count);
-	return count;
+	int rc;
+
+	rc = kobject_synth_uevent(&mk->kobj, buffer, count);
+	return rc ? rc : count;
 }
 
 struct module_attribute module_uevent =
-- 
2.19.1