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

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Message-ID: <dddca63c-088c-d87c-370f-e8f02d1b0d04@linuxfoundation.org>
Date:   Tue, 13 Oct 2020 11:28:07 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Andrey Konovalov <andreyknvl@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-usb@...r.kernel.org, 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>,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH v2] kcov, usbip: collect coverage from vhci_rx_loop

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?
>   
>   	spin_unlock(&vdev->ud.lock);
>   	spin_unlock_irqrestore(&vhci->lock, flags);
> 

thanks,
-- Shuah