[PATCH v2 2/3] usb, kcov: collect coverage from hub_event

[Andrey Konovalov <andreyknvl@google.com>]

This patch adds kcov_remote_start()/kcov_remote_stop() annotations to the
hub_event() function, which is responsible for processing events on USB
buses, in particular events that happen during USB device enumeration.
Since hub_event() is run in a global background kernel thread (see
Documentation/dev-tools/kcov.rst for details), each USB bus gets a unique
global handle id from the USB subsystem kcov handle id range. As the
result kcov can now be used to collect coverage from events that happen on
a particular USB bus.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 drivers/usb/core/hub.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 236313f41f4a..823dd675f6db 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -29,6 +29,7 @@
 #include <linux/random.h>
 #include <linux/pm_qos.h>
 #include <linux/kobject.h>
+#include <linux/kcov.h>
 
 #include <linux/uaccess.h>
 #include <asm/byteorder.h>
@@ -5374,6 +5375,8 @@ static void hub_event(struct work_struct *work)
 	hub_dev = hub->intfdev;
 	intf = to_usb_interface(hub_dev);
 
+	kcov_remote_start_usb((u64)hdev->bus->busnum);
+
 	dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04x\n",
 			hdev->state, hdev->maxchild,
 			/* NOTE: expects max 15 ports... */
@@ -5480,6 +5483,8 @@ static void hub_event(struct work_struct *work)
 	/* Balance the stuff in kick_hub_wq() and allow autosuspend */
 	usb_autopm_put_interface(intf);
 	kref_put(&hub->kref, hub_release);
+
+	kcov_remote_stop();
 }
 
 static const struct usb_device_id hub_id_table[] = {
-- 
2.24.0.rc0.303.g954a862665-goog