linux-kernel - Re: [PATCH v3] kcov, usbip: collect coverage from vhci_rx

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Message-ID: <ca9c83b0-364a-6a26-4539-e38373a455aa@linuxfoundation.org>
Date:   Mon, 19 Oct 2020 12:49:35 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Andrey Konovalov <andreyknvl@...gle.com>,
        Shuah Khan <shuah@...nel.org>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.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 v3] kcov, usbip: collect coverage from vhci_rx_loop

On 10/19/20 11:20 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>
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> ---
> 
> Changes v2->v3:
> - Fix build without KCOV enabled.
> 
> ---
>   drivers/usb/usbip/usbip_common.h | 4 ++++
>   drivers/usb/usbip/vhci_rx.c      | 7 +++++++
>   drivers/usb/usbip/vhci_sysfs.c   | 4 ++++
>   3 files changed, 15 insertions(+)
> 
> 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..68ec0aa64f69 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 +262,13 @@ int vhci_rx_loop(void *data)
>   		if (usbip_event_happened(ud))
>   			break;
>   
> +#ifdef CONFIG_KCOV
> +		kcov_remote_start_common(ud->kcov_handle);
> +#endif
>   		vhci_rx_pdu(ud);
> +#ifdef CONFIG_KCOV
> +		kcov_remote_stop();
> +#endif
>   	}

Let's move these into usbip_common.h as inline functions along
the line of

#ifdef CONFIG_KCOV
usbip_kcov_remote_start_common(ud)
{
   kcov_remote_start_common(ud->kcov_handle);
}

usbip_kcov_remote_stop_common(ud)
{
   kcov_remote_stop_common(ud->kcov_handle);
}
#else
stubs that do nothing
#endif

>   
>   	return 0;
> diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c
> index be37aec250c2..e167b8a445ad 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>
> @@ -383,6 +384,9 @@ static ssize_t attach_store(struct device *dev, struct device_attribute *attr,
>   	vdev->ud.sockfd     = sockfd;
>   	vdev->ud.tcp_socket = socket;
>   	vdev->ud.status     = VDEV_ST_NOTASSIGNED;
> +#ifdef CONFIG_KCOV
> +	vdev->ud.kcov_handle = kcov_common_handle();
> +#endif


Same here add a usbip_kcov_handle_init(ud)

thanks,
-- Shuah