Raspberry Pi + WiFiを安定させるVer3

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~/src $ vim usbreset.c

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#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>

#include <linux/usbdevice_fs.h>

int main(int argc, char **argv)
{
    const char *filename;
    int fd;
    int rc;

    if (argc != 2) {
        fprintf(stderr, "Usage: usbreset device-filename\n");
        return 1;
    }
    filename = argv[1];

    fd = open(filename, O_WRONLY);
    if (fd < 0) {
        perror("Error opening output file");
        return 1;
    }

    printf("Resetting USB device %s\n", filename);
    rc = ioctl(fd, USBDEVFS_RESET, 0);
    if (rc < 0) {
        perror("Error in ioctl");
        return 1;
    }
    printf("Reset successful\n");

    close(fd);
    return 0;
}

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~/src $ cc usbreset.c -o usbreset
~/src $ ls -la
total 20
drwxr-xr-x 2 pi pi 4096 Nov 11 19:36 .
drwxr-xr-x 7 pi pi 4096 Nov 11 19:35 ..
-rwxr-xr-x 1 pi pi 6373 Nov 11 19:36 usbreset
-rw-r--r-- 1 pi pi  706 Nov 11 19:35 usbreset.c

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~/src $ sudo lsusb | grep "Wireless LAN Adapter"
Bus 001 Device 007: ID 0411:0158 BUFFALO INC. (formerly MelCo., Inc.) WLI-UC-GNHP Wireless LAN Adapter
~/src $ sudo ./usbreset /dev/bus/usb/001/007

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~/src $ sudo lsusb | grep "USB-2.0 4-Port HUB"
Bus 001 Device 004: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
~/src $ sudo ./usbreset /dev/bus/usb/001/004
Resetting USB device /dev/bus/usb/001/004
Reset successful

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#!/bin/bash

# reset usb device by name (part)
# arg1: part of usb device name
reset_usb_device()
{
        local dev_name="$1"
        local usb_info=`lsusb | grep "$dev_name"`

        echo $usb_info
        local bus_num=`echo $usb_info | awk '{ printf("%.3s", $2) }'`
        local dev_num=`echo $usb_info | awk '{ printf("%.3s", $4) }'`

        local usb_dev_file=/dev/bus/usb/$bus_num/$dev_num

        echo $usb_dev_file

        /home/pi/src/usbreset $usb_dev_file

        #lsusb >> /home/pi/src/lsusb.txt
}

# check network status
# return: 0: inactive
#         1: active
is_network_active()
{
        local cnn=`/sbin/ifconfig wlan0 | /bin/grep  "inet addr:"`
        if [ "$cnn" = "" ]; then
                return 0
        fi
        return 1
}

# restart wlan0
wlan0_up()
{
        local act=0
        local retry=0
        while [ $act -eq 0 ]
        do
                ifup --force wlan0
                is_network_active
                act=$?
                echo $act
                retry=`expr $retry + 1`
        done
        echo retry $retry
}

# main
is_network_active
if  [ $? -eq 0 ]; then
        reset_usb_device "WLI-UC-GNHP Wireless LAN Adapter"
        #reset_usb_device "Genesys Logic, Inc. USB-2.0 4-Port HUB"
        sleep 5s        #wait for device up
        wlan0_up        #ifup
        logger "wlan0 restarted"
fi