linux-kernel - Re: [PATCH v2] kcov, usbip: collect coverage from vhci_rx

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Date:   Wed, 14 Oct 2020 17:54:01 +0200
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Shuah Khan <skhan@...uxfoundation.org>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        USB list <linux-usb@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Shuah Khan <shuah@...nel.org>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Aleksandr Nogikh <nogikh@...gle.com>,
        Nazime Hande Harputluoglu <handeharput@...il.com>,
        Nazime Hande Harputluoglu <handeharputlu@...gle.com>
Subject: Re: [PATCH v2] kcov, usbip: collect coverage from vhci_rx_loop

On Tue, Oct 13, 2020 at 7:28 PM Shuah Khan <skhan@...uxfoundation.org> wrote:
>
> On 10/12/20 11:10 AM, Andrey Konovalov wrote:
> > From: Nazime Hande Harputluoglu <handeharputlu@...gle.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 <handeharputlu@...gle.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?

Yeah, this breaks without CONFIG_KCOV, my bad.

I'll fix everything and submit v3.

Thank you!