Re: [PATCH v2] kcov, usbip: collect coverage from vhci_rx_loop

[Shuah Khan]

On 10/12/20 11:10 AM, Andrey Konovalov wrote:

From: Nazime Hande Harputluoglu <handeharpu...@google.com>

Add kcov_remote_start()/kcov_remote_stop() annotations to the
vhci_rx_loop() function, which is responsible for parsing USB/IP packets
coming into USB/IP client.

Since vhci_rx_loop() threads are spawned per vhci_hcd device instance, the
common kcov handle is used for kcov_remote_start()/stop() annotations
(see Documentation/dev-tools/kcov.rst for details). As the result kcov
can now be used to collect coverage from vhci_rx_loop() threads.

Signed-off-by: Nazime Hande Harputluoglu <handeharpu...@google.com>
---

Changes v1->v2:
- Fix spacing issues.
- Add ifdef CONFIG_KCOV around kcov_handle in usbip_device struct.

Does this compile without CONFIG_KCOV?

---
  drivers/usb/usbip/usbip_common.h |  4 ++++
  drivers/usb/usbip/vhci_rx.c      |  3 +++
  drivers/usb/usbip/vhci_sysfs.c   | 12 +++++++-----
  3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/usbip/usbip_common.h b/drivers/usb/usbip/usbip_common.h
index 8be857a4fa13..0906182011d6 100644
--- a/drivers/usb/usbip/usbip_common.h
+++ b/drivers/usb/usbip/usbip_common.h
@@ -277,6 +277,10 @@ struct usbip_device {
                void (*reset)(struct usbip_device *);
                void (*unusable)(struct usbip_device *);
        } eh_ops;
+
+#ifdef CONFIG_KCOV
+       u64 kcov_handle;
+#endif
  };

#define kthread_get_run(threadfn, data, namefmt, ...) \

diff --git a/drivers/usb/usbip/vhci_rx.c b/drivers/usb/usbip/vhci_rx.c
index 266024cbb64f..473f14587bd5 100644
--- a/drivers/usb/usbip/vhci_rx.c
+++ b/drivers/usb/usbip/vhci_rx.c
@@ -3,6 +3,7 @@
   * Copyright (C) 2003-2008 Takahiro Hirofuchi
   */

+#include <linux/kcov.h>

  #include <linux/kthread.h>
  #include <linux/slab.h>

@@ -261,7 +262,9 @@ int vhci_rx_loop(void *data)

                if (usbip_event_happened(ud))
                        break;

+ kcov_remote_start_common(ud->kcov_handle);

You are referencing kcov_handle defined in CONFIG_KCOV scope
here. Does this compile for you without CONFIG_KCOV?

                vhci_rx_pdu(ud);
+               kcov_remote_stop();
        }

return 0;

diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c
index be37aec250c2..966f1f5cafb1 100644
--- a/drivers/usb/usbip/vhci_sysfs.c
+++ b/drivers/usb/usbip/vhci_sysfs.c
@@ -4,6 +4,7 @@
   * Copyright (C) 2015-2016 Nobuo Iwata
   */

+#include <linux/kcov.h>

  #include <linux/kthread.h>
  #include <linux/file.h>
  #include <linux/net.h>
@@ -378,11 +379,12 @@ static ssize_t attach_store(struct device *dev, struct 
device_attribute *attr,
        dev_info(dev, "devid(%u) speed(%u) speed_str(%s)\n",
                 devid, speed, usb_speed_string(speed));

- vdev->devid = devid;

-       vdev->speed         = speed;
-       vdev->ud.sockfd     = sockfd;
-       vdev->ud.tcp_socket = socket;
-       vdev->ud.status     = VDEV_ST_NOTASSIGNED;
+       vdev->devid          = devid;
+       vdev->speed          = speed;
+       vdev->ud.sockfd      = sockfd;
+       vdev->ud.tcp_socket  = socket;
+       vdev->ud.status      = VDEV_ST_NOTASSIGNED;
+       vdev->ud.kcov_handle = kcov_common_handle();

Don't change spacing for other variables. Add just the new
code. Don't you need CONFIG_KCOV around this new code?

spin_unlock(&vdev->ud.lock);

        spin_unlock_irqrestore(&vhci->lock, flags);

thanks,
-- Shuah