[PATCH v3 2/3] usb, kcov: collect coverage from hub_event

From: Andrey Konovalov
Date: Tue Oct 29 2019 - 12:32:52 EST

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 from the USB subsystem kcov handle 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@xxxxxxxxxx>
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 */
kref_put(&hub->kref, hub_release);
+ kcov_remote_stop();

static const struct usb_device_id hub_id_table[] = {