Date:	Thu, 06 Mar 2014 09:15:01 -0700
From:	Shuah Khan <shuah.kh@...sung.com>
To:	Valentina Manea <valentina.manea.m@...il.com>,
	gregkh@...uxfoundation.org
Cc:	tobias.polzer@....de, dominik.paulus@....de,
	ly80toro@....cs.fau.de, ihadzic@...earch.bell-labs.com,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	devel@...verdev.osuosl.org, firefly@...ts.rosedu.org,
	Shuah Khan <shuah.kh@...sung.com>
Subject: Re: [PATCH 01/12] staging: usbip: userspace: migrate usbip_bind to
 libudev

On 03/04/2014 12:10 PM, Valentina Manea wrote:
> This patch adds autoconf check for libudev and migrates
> usbip_bind to the new library.
>
> libsysfs will still be used until all userspace is modified.
>
> Signed-off-by: Valentina Manea <valentina.manea.m@...il.com>
> ---
>   drivers/staging/usbip/userspace/configure.ac       |   6 +
>   .../staging/usbip/userspace/libsrc/usbip_common.h  |   9 ++
>   drivers/staging/usbip/userspace/src/Makefile.am    |   3 +-
>   drivers/staging/usbip/userspace/src/sysfs_utils.c  |  36 +++++
>   drivers/staging/usbip/userspace/src/sysfs_utils.h  |   8 ++
>   drivers/staging/usbip/userspace/src/usbip_bind.c   | 149 +++++++++------------
>   drivers/staging/usbip/userspace/src/utils.c        |  51 +++----
>   7 files changed, 136 insertions(+), 126 deletions(-)
>   create mode 100644 drivers/staging/usbip/userspace/src/sysfs_utils.c
>   create mode 100644 drivers/staging/usbip/userspace/src/sysfs_utils.h
>
> diff --git a/drivers/staging/usbip/userspace/configure.ac b/drivers/staging/usbip/userspace/configure.ac
> index 0ee5d92..a5193c6 100644
> --- a/drivers/staging/usbip/userspace/configure.ac
> +++ b/drivers/staging/usbip/userspace/configure.ac
> @@ -50,6 +50,12 @@ AC_CHECK_HEADER([sysfs/libsysfs.h],
>   			      [AC_MSG_ERROR([Missing sysfs2 library!])])],
>   		[AC_MSG_ERROR([Missing /usr/include/sysfs/libsysfs.h])])
>
> +AC_CHECK_HEADER([libudev.h],
> +		[AC_CHECK_LIB([udev], [udev_new],
> +			      [LIBS="$LIBS -ludev"],
> +			      [AC_MSG_ERROR([Missing udev library!])])],
> +		[AC_MSG_ERROR([Missing /usr/include/libudev.h])])
> +
>   # Checks for libwrap library.
>   AC_MSG_CHECKING([whether to use the libwrap (TCP wrappers) library])
>   AC_ARG_WITH([tcp-wrappers],
> diff --git a/drivers/staging/usbip/userspace/libsrc/usbip_common.h b/drivers/staging/usbip/userspace/libsrc/usbip_common.h
> index 2cb81b3..565ac78 100644
> --- a/drivers/staging/usbip/userspace/libsrc/usbip_common.h
> +++ b/drivers/staging/usbip/userspace/libsrc/usbip_common.h
> @@ -29,6 +29,15 @@
>   #define USBIP_HOST_DRV_NAME	"usbip-host"
>   #define USBIP_VHCI_DRV_NAME	"vhci_hcd"
>
> +/* sysfs constants */
> +#define SYSFS_MNT_PATH         "/sys"
> +#define SYSFS_BUS_NAME         "bus"
> +#define SYSFS_BUS_TYPE         "usb"
> +#define SYSFS_DRIVERS_NAME     "drivers"
> +
> +#define SYSFS_PATH_MAX		256
> +#define SYSFS_BUS_ID_SIZE	32

I wish we have some global defines we could use.

> +
>   extern int usbip_use_syslog;
>   extern int usbip_use_stderr;
>   extern int usbip_use_debug ;
> diff --git a/drivers/staging/usbip/userspace/src/Makefile.am b/drivers/staging/usbip/userspace/src/Makefile.am
> index b4f8c4b..6c91bcb 100644
> --- a/drivers/staging/usbip/userspace/src/Makefile.am
> +++ b/drivers/staging/usbip/userspace/src/Makefile.am
> @@ -6,7 +6,8 @@ sbin_PROGRAMS := usbip usbipd
>
>   usbip_SOURCES := usbip.h utils.h usbip.c utils.c usbip_network.c \
>   		 usbip_attach.c usbip_detach.c usbip_list.c \
> -		 usbip_bind.c usbip_unbind.c usbip_port.c
> +		 usbip_bind.c usbip_unbind.c usbip_port.c \
> +		 sysfs_utils.c
>
>
>   usbipd_SOURCES := usbip_network.h usbipd.c usbip_network.c
> diff --git a/drivers/staging/usbip/userspace/src/sysfs_utils.c b/drivers/staging/usbip/userspace/src/sysfs_utils.c
> new file mode 100644
> index 0000000..2c362d1
> --- /dev/null
> +++ b/drivers/staging/usbip/userspace/src/sysfs_utils.c
> @@ -0,0 +1,36 @@
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +#include <errno.h>
> +
> +#include "sysfs_utils.h"
> +#include "usbip_common.h"
> +
> +int write_sysfs_attribute(const char *attr_path, const char *new_value,
> +			  size_t len)
> +{
> +	int fd;
> +	int length;
> +
> +	if (attr_path == NULL || new_value == NULL || len == 0) {
> +		dbg("Invalid values provided for attribute %s.", attr_path);
> +		errno = EINVAL;
> +		return -1;
> +	}
> +
> +	if ((fd = open(attr_path, O_WRONLY)) < 0) {
> +		dbg("Error opening attribute %s.", attr_path);
> +		return -1;
> +	}
> +
> +	length = write(fd, new_value, len);
> +	if (length < 0) {
> +		dbg("Error writing to attribute %s.", attr_path);
> +		close(fd);
> +		return -1;
> +	}
> +
> +	close(fd);
> +
> +	return 0;
> +}
> diff --git a/drivers/staging/usbip/userspace/src/sysfs_utils.h b/drivers/staging/usbip/userspace/src/sysfs_utils.h
> new file mode 100644
> index 0000000..32ac1d1
> --- /dev/null
> +++ b/drivers/staging/usbip/userspace/src/sysfs_utils.h
> @@ -0,0 +1,8 @@
> +
> +#ifndef __SYSFS_UTILS_H
> +#define __SYSFS_UTILS_H
> +
> +int write_sysfs_attribute(const char *attr_path, const char *new_value,
> +			  size_t len);
> +
> +#endif
> diff --git a/drivers/staging/usbip/userspace/src/usbip_bind.c b/drivers/staging/usbip/userspace/src/usbip_bind.c
> index 8cfd2db..d122089 100644
> --- a/drivers/staging/usbip/userspace/src/usbip_bind.c
> +++ b/drivers/staging/usbip/userspace/src/usbip_bind.c
> @@ -16,7 +16,7 @@
>    * along with this program. If not, see <http://www.gnu.org/licenses/>.
>    */
>
> -#include <sysfs/libsysfs.h>
> +#include <libudev.h>
>
>   #include <errno.h>
>   #include <stdio.h>
> @@ -28,6 +28,7 @@
>   #include "usbip_common.h"
>   #include "utils.h"
>   #include "usbip.h"
> +#include "sysfs_utils.h"
>
>   enum unbind_status {
>   	UNBIND_ST_OK,
> @@ -48,135 +49,94 @@ void usbip_bind_usage(void)
>   /* call at unbound state */
>   static int bind_usbip(char *busid)
>   {
> -	char bus_type[] = "usb";
>   	char attr_name[] = "bind";
> -	char sysfs_mntpath[SYSFS_PATH_MAX];
>   	char bind_attr_path[SYSFS_PATH_MAX];
> -	struct sysfs_attribute *bind_attr;
> -	int failed = 0;
> -	int rc, ret = -1;
> -
> -	rc = sysfs_get_mnt_path(sysfs_mntpath, SYSFS_PATH_MAX);
> -	if (rc < 0) {
> -		err("sysfs must be mounted: %s", strerror(errno));
> -		return -1;
> -	}
> +	int rc = -1;
>
>   	snprintf(bind_attr_path, sizeof(bind_attr_path), "%s/%s/%s/%s/%s/%s",
> -		 sysfs_mntpath, SYSFS_BUS_NAME, bus_type, SYSFS_DRIVERS_NAME,
> -		 USBIP_HOST_DRV_NAME, attr_name);
> +		 SYSFS_MNT_PATH, SYSFS_BUS_NAME, SYSFS_BUS_TYPE,
> +		 SYSFS_DRIVERS_NAME, USBIP_HOST_DRV_NAME, attr_name);
> +	dbg("bind attribute path: %s", bind_attr_path);

Is this needed since there are error messages in the error paths?

>
> -	bind_attr = sysfs_open_attribute(bind_attr_path);
> -	if (!bind_attr) {
> -		dbg("problem getting bind attribute: %s", strerror(errno));
> -		return -1;
> -	}
> -
> -	rc = sysfs_write_attribute(bind_attr, busid, SYSFS_BUS_ID_SIZE);
> +	rc = write_sysfs_attribute(bind_attr_path, busid, strlen(busid));
>   	if (rc < 0) {
> -		dbg("bind driver at %s failed", busid);
> -		failed = 1;
> +		dbg("Error binding device %s to driver: %s", busid,
> +		    strerror(errno));

I think it would make sense to have this as an error as opposed to debug 
only message.

> +		return -1;
>   	}
>
> -	if (!failed)
> -		ret = 0;
> -
> -	sysfs_close_attribute(bind_attr);
> -
> -	return ret;
> +	return 0;
>   }
>
>   /* buggy driver may cause dead lock */
>   static int unbind_other(char *busid)
>   {
> -	char bus_type[] = "usb";
> -	struct sysfs_device *busid_dev;
> -	struct sysfs_device *dev;
> -	struct sysfs_driver *drv;
> -	struct sysfs_attribute *unbind_attr;
> -	struct sysfs_attribute *bDevClass;
> -	int rc;
>   	enum unbind_status status = UNBIND_ST_OK;
>
> -	busid_dev = sysfs_open_device(bus_type, busid);
> -	if (!busid_dev) {
> -		dbg("sysfs_open_device %s failed: %s", busid, strerror(errno));
> -		return -1;
> -	}
> -	dbg("busid path: %s", busid_dev->path);
> +	char attr_name[] = "unbind";
> +	char unbind_attr_path[SYSFS_PATH_MAX];
> +	int rc = -1;
>
> -	bDevClass  = sysfs_get_device_attr(busid_dev, "bDeviceClass");
> -	if (!bDevClass) {
> -		dbg("problem getting device attribute: %s",
> -		    strerror(errno));
> +	struct udev *udev;
> +	struct udev_device *dev;
> +	const char *driver;
> +	const char *bDevClass;
> +
> +	/* Create libudev context. */
> +	udev = udev_new();
> +
> +	/* Get the device. */
> +	dev = udev_device_new_from_subsystem_sysname(udev, "usb", busid);
> +	if (!dev) {
> +		dbg("Unable to find device with bus ID %s.", busid);
>   		goto err_close_busid_dev;
>   	}
>
> -	if (!strncmp(bDevClass->value, "09", bDevClass->len)) {
> -		dbg("skip unbinding of hub");
> +	/* Check what kind of device it is. */
> +	bDevClass  = udev_device_get_sysattr_value(dev, "bDeviceClass");
> +	if (!bDevClass) {
> +		dbg("Unable to get bDevClass device attribute.");
>   		goto err_close_busid_dev;
>   	}
>
> -	dev = sysfs_open_device(bus_type, busid);
> -	if (!dev) {
> -		dbg("could not open device: %s",
> -				strerror(errno));
> +	if (!strncmp(bDevClass, "09", strlen(bDevClass))) {
> +		dbg("Skip unbinding of hub.");
>   		goto err_close_busid_dev;
>   	}
>
> -	dbg("%s -> %s", dev->name,  dev->driver_name);
> -
> -	if (!strncmp("unknown", dev->driver_name, SYSFS_NAME_LEN)) {
> -		/* unbound interface */
> -		sysfs_close_device(dev);
> +	/* Get the device driver. */
> +	driver = udev_device_get_driver(dev);
> +	if (!driver) {
> +		/* No driver bound to this device. */
>   		goto out;
>   	}
>
> -	if (!strncmp(USBIP_HOST_DRV_NAME, dev->driver_name,
> -				SYSFS_NAME_LEN)) {
> -		/* already bound to usbip-host */
> +	if (!strncmp(USBIP_HOST_DRV_NAME, driver,
> +				strlen(USBIP_HOST_DRV_NAME))) {
> +		/* Already bound to usbip-host. */
>   		status = UNBIND_ST_USBIP_HOST;
> -		sysfs_close_device(dev);
>   		goto out;
>   	}
>
> -	/* unbinding */
> -	drv = sysfs_open_driver(bus_type, dev->driver_name);
> -	if (!drv) {
> -		dbg("could not open device driver on %s: %s",
> -				dev->name, strerror(errno));
> -		goto err_close_intf_dev;
> -	}
> -	dbg("device driver: %s", drv->path);
> -
> -	unbind_attr = sysfs_get_driver_attr(drv, "unbind");
> -	if (!unbind_attr) {
> -		dbg("problem getting device driver attribute: %s",
> -				strerror(errno));
> -		goto err_close_intf_drv;
> -	}
> +	/* Unbind device from driver. */
> +	snprintf(unbind_attr_path, sizeof(unbind_attr_path), "%s/%s/%s/%s/%s/%s",
> +		 SYSFS_MNT_PATH, SYSFS_BUS_NAME, SYSFS_BUS_TYPE,
> +		 SYSFS_DRIVERS_NAME, driver, attr_name);
> +	dbg("unbind attribute path: %s", unbind_attr_path);

I think this could be removed since there are error messages in failure 
legs. I am finding usbip userspace is rather prolific with debug. So it 
would help if err() is used in error legs as opposed to dbg() and use 
dbg() only for debug messages.

>
> -	rc = sysfs_write_attribute(unbind_attr, dev->bus_id,
> -			SYSFS_BUS_ID_SIZE);
> +	rc = write_sysfs_attribute(unbind_attr_path, busid, strlen(busid));
>   	if (rc < 0) {
> -		/* NOTE: why keep unbinding other interfaces? */
> -		dbg("unbind driver at %s failed", dev->bus_id);
> -		status = UNBIND_ST_FAILED;
> +		dbg("Error unbinding device %s from driver.", busid);

This could be err() instead of dbg()

> +		goto err_close_busid_dev;
>   	}
>
> -	sysfs_close_driver(drv);
> -	sysfs_close_device(dev);
> -
>   	goto out;
>
> -err_close_intf_drv:
> -	sysfs_close_driver(drv);
> -err_close_intf_dev:
> -	sysfs_close_device(dev);
>   err_close_busid_dev:
>   	status = UNBIND_ST_FAILED;
>   out:
> -	sysfs_close_device(busid_dev);
> +	udev_device_unref(dev);
> +	udev_unref(udev);
>
>   	return status;
>   }
> @@ -184,6 +144,17 @@ out:
>   static int bind_device(char *busid)
>   {
>   	int rc;
> +	struct udev *udev;
> +	struct udev_device *dev;
> +
> +	/* Check whether the device with this bus ID exists. */
> +	udev = udev_new();
> +	dev = udev_device_new_from_subsystem_sysname(udev, "usb", busid);
> +	if (!dev) {
> +		err("Device with the specified bus ID does not exist.");
> +		return -1;
> +	}
> +	udev_unref(udev);
>
>   	rc = unbind_other(busid);
>   	if (rc == UNBIND_ST_FAILED) {
> diff --git a/drivers/staging/usbip/userspace/src/utils.c b/drivers/staging/usbip/userspace/src/utils.c
> index 2d4966e..c75acac 100644
> --- a/drivers/staging/usbip/userspace/src/utils.c
> +++ b/drivers/staging/usbip/userspace/src/utils.c
> @@ -16,61 +16,40 @@
>    * along with this program. If not, see <http://www.gnu.org/licenses/>.
>    */
>
> -#include <sysfs/libsysfs.h>
> -
>   #include <errno.h>
>   #include <stdio.h>
>   #include <string.h>
>
>   #include "usbip_common.h"
>   #include "utils.h"
> +#include "sysfs_utils.h"
>
>   int modify_match_busid(char *busid, int add)
>   {
> -	char bus_type[] = "usb";
>   	char attr_name[] = "match_busid";
> -	char buff[SYSFS_BUS_ID_SIZE + 4];
> -	char sysfs_mntpath[SYSFS_PATH_MAX];
> +	char command[SYSFS_BUS_ID_SIZE + 4];
>   	char match_busid_attr_path[SYSFS_PATH_MAX];
> -	struct sysfs_attribute *match_busid_attr;
> -	int rc, ret = 0;
> -
> -	if (strnlen(busid, SYSFS_BUS_ID_SIZE) > SYSFS_BUS_ID_SIZE - 1) {
> -		dbg("busid is too long");
> -		return -1;
> -	}
> -
> -	rc = sysfs_get_mnt_path(sysfs_mntpath, SYSFS_PATH_MAX);
> -	if (rc < 0) {
> -		err("sysfs must be mounted: %s", strerror(errno));
> -		return -1;
> -	}
> +	int rc;
>
>   	snprintf(match_busid_attr_path, sizeof(match_busid_attr_path),
> -		 "%s/%s/%s/%s/%s/%s", sysfs_mntpath, SYSFS_BUS_NAME, bus_type,
> -		 SYSFS_DRIVERS_NAME, USBIP_HOST_DRV_NAME, attr_name);
> -
> -	match_busid_attr = sysfs_open_attribute(match_busid_attr_path);
> -	if (!match_busid_attr) {
> -		dbg("problem getting match_busid attribute: %s",
> -		    strerror(errno));
> -		return -1;
> -	}
> +		 "%s/%s/%s/%s/%s/%s", SYSFS_MNT_PATH, SYSFS_BUS_NAME,
> +		 SYSFS_BUS_TYPE, SYSFS_DRIVERS_NAME, USBIP_HOST_DRV_NAME,
> +		 attr_name);
> +	dbg("match_busid attribute path: %s", match_busid_attr_path);
>
>   	if (add)
> -		snprintf(buff, SYSFS_BUS_ID_SIZE + 4, "add %s", busid);
> +		snprintf(command, SYSFS_BUS_ID_SIZE + 4, "add %s", busid);
>   	else
> -		snprintf(buff, SYSFS_BUS_ID_SIZE + 4, "del %s", busid);
> +		snprintf(command, SYSFS_BUS_ID_SIZE + 4, "del %s", busid);
>
> -	dbg("write \"%s\" to %s", buff, match_busid_attr->path);
> +	dbg("write \"%s\" to %s", command, match_busid_attr_path);

This messge could be removed.

>
> -	rc = sysfs_write_attribute(match_busid_attr, buff, sizeof(buff));
> +	rc = write_sysfs_attribute(match_busid_attr_path, command,
> +				   sizeof(command));
>   	if (rc < 0) {
> -		dbg("failed to write match_busid: %s", strerror(errno));
> -		ret = -1;
> +		dbg("Failed to write match_busid: %s", strerror(errno));
> +		return -1;
>   	}
>
> -	sysfs_close_attribute(match_busid_attr);
> -
> -	return ret;
> +	return 0;
>   }
>

Good work. Thanks for doing this. You have my Reviewed-by after making 
the recommended changes.

Reviewed-by: Shuah Khan <shuah.kh@...sung.com>

-- Shuah

-- 
Shuah Khan
Senior Linux Kernel Developer - Open Source Group
Samsung Research America(Silicon Valley)
shuah.kh@...sung.com | (970) 672-0658
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