#include”header.h”

dev_t dev;

void bulk_request(struct request_queue *q)

{
struct request *req;

req = blk_fetch_request(q);

while (req != NULL)
{

if (req == NULL || (req->cmd_type != REQ_TYPE_FS))
{
printk (KERN_NOTICE “Skip non-CMD request\n”);
__blk_end_request_all(req, -EIO);
continue;

}

}
}

int __init start(void)
{
//int reg;

// struct request *disk;

static struct request_queue *Queue;

printk(KERN_INFO “Begin : %s\n”,__func__);

printk(KERN_INFO” HELLO KERNEL”);
sbullmajor=register_blkdev(sbullmajor,device_name);

if(sbullmajor)
{

#ifdef DEBUG

printk(KERN_INFO ” Registration Sucessful\n “);

printk(KERN_INFO”Major no is %d\n”,sbullmajor);

#endif

}
else

{

#ifdef DEBUG

printk(KERN_INFO “Registartion failed\n “);

#endif
}
sbulldev=kmalloc(sizeof(struct Sbulldev),GFP_KERNEL);

memset(sbulldev,”,sizeof(struct Sbulldev));

sbulldev->size=hardsect_size;

sbulldev->data=vmalloc(sbulldev->size);

if(sbulldev->data ==NULL )

{
#ifdef DEBUG
printk(KERN_INFO ” Memory allocation failed\n “);

#endif

}
else

{
#ifdef DEBUG

printk(KERN_INFO ” Memory allocation of block device sucessful\n “);

#endif
}

spin_lock_init(&sbulldev->lock);

#ifdef DEBUG
printk(KERN_INFO ” after spin_lock\n “);

#endif
sbulldev->gd=alloc_disk(16);

if(sbulldev->gd==NULL){ //no of minors is 1 no partioning;

#ifdef DEBUG
printk(KERN_INFO ” alloc_disk failed\n “);

#endif

goto OUT;

}

else

{
#ifdef DEBUG

printk(KERN_INFO ” alloc_disk sucessful\n “);

#endif
}
Queue=blk_init_queue(bulk_request,NULL);

blk_queue_logical_block_size(Queue,hardsect_size);

sbulldev->gd->major=sbullmajor;

#ifdef DEBUG

printk(KERN_INFO ” sbullmajor\n “);

#endif

sbulldev->gd->minors=sbullminor;
#ifdef DEBUG

printk(KERN_INFO ” sbullminor\n “);

#endif

sbulldev->gd->first_minor=1;

#ifdef DEBUG

printk(KERN_INFO ” first_minor\n “);

#endif

sbulldev->gd->fops=f_ops;

#ifdef DEBUG

printk(KERN_INFO ” file_operations\n “);

#endif

sbulldev->gd->queue=Queue;

#ifdef DEBUG

printk(KERN_INFO ” Queue\n “);

#endif

sbulldev->gd->private_data=sbulldev;

#ifdef DEBUG

printk(KERN_INFO ” private_data\n “);

#endif

strcpy(sbulldev->gd->disk_name ,”sbulla” );

#ifdef DEBUG

printk(KERN_INFO ” sbulla\n “);

#endif

set_capacity(sbulldev->gd,hardsect_size);

#ifdef DEBUG

printk(KERN_INFO ” set_capacity\n “);

#endif
add_disk(sbulldev->gd);

#ifdef DEBUG

printk(KERN_INFO ” add disk\n “);

#endif

#ifdef DEBUG

printk(KERN_INFO ” End of %s\n “,__func__);

#endif

OUT:

return -1;

return 0;

}
void __exit release(void)
{

//int i;

#ifdef DEBUG

printk(KERN_INFO “exit : %s\n”,__func__);

#endif
del_gendisk(sbulldev->gd);

printk(KERN_INFO ” add disk\n “);

blk_cleanup_queue(sbulldev->queue);

printk(KERN_INFO ” add disk\n “);

//put_disk(sbulldev->gd);

 
unregister_blkdev(sbullmajor,device_name);
printk(KERN_INFO “BYE KERNEL”);
}
module_init(start);

module_exit(release);

}

the driver crashes  moment insmod ./modules/lkm.ko is done…..ha i have zero bytes of home drive  does this effect

the driver crashes the moment it reaches add_disk…….following are the /var/log/messages…….rest works properly…..
hope if ani one helps.ya mi home directory has 0 bytes memory

Aug 5 10:03:45 zaffer kernel: [ 5936.683085]
Begin : start

Aug 5 10:03:45 zaffer kernel:
[ 5936.683087] HELLO KERNEL

Aug 5 10:03:45 zaffer kernel:[ 5936.683090] Registration Sucessful

Aug 5 10:03:45 zaffer kernel: [ 5936.683091]

Aug 5 10:03:45 zaffer kernel: [ 5936.683093] Major no is 252

Aug 5 10:03:45 zaffer kernel: [ 5936.683134] Memory allocation of block device sucessful

Aug 5 10:03:45 zaffer kernel: [ 5936.683135]

Aug 5 10:03:45 zaffer kernel: [ 5936.683136] after spin_lock

Aug 5 10:03:45 zaffer kernel: [ 5936.683137]

Aug 5 10:03:45 zaffer kernel: [ 5936.683145] alloc_disk sucessful

Aug 5 10:03:45 zaffer kernel: [ 5936.683146]

Aug 5 10:03:45 zaffer kernel: [ 5936.683161] sbullmajor

Aug 5 10:03:45 zaffer kernel: [ 5936.683162]

Aug 5 10:03:45 zaffer kernel: [ 5936.683163] sbullminor

Aug 5 10:03:45 zaffer kernel: [ 5936.683164]

Aug 5 10:03:45 zaffer kernel: [ 5936.683165] first_minor

Aug 5 10:03:45 zaffer kernel: [ 5936.683166]

Aug 5 10:03:45 zaffer kernel: [ 5936.683167] file_operations

Aug 5 10:03:45 zaffer kernel: [ 5936.683168]

Aug 5 10:03:45 zaffer kernel: [ 5936.683169] Queue

Aug 5 10:03:45 zaffer kernel: [ 5936.683169]

Aug 5 10:03:45 zaffer kernel: [ 5936.683170] private_data

Aug 5 10:03:45 zaffer kernel: [ 5936.683171]

Aug 5 10:03:45 zaffer kernel: [ 5936.683172] sbulla

Aug 5 10:03:45 zaffer kernel: [ 5936.683173]

Aug 5 10:03:45 zaffer kernel: [ 5936.683174] set_capacity

Aug 5 10:03:45 zaffer kernel: [ 5936.683175]

Aug 5 10:03:45 zaffer kernel: [ 5936.683176] ————[ cut here ]————
Aug 5 10:03:45 zaffer kernel: [ 5936.683183] WARNING: at block/genhd.c:527 add_disk+0x4d/0xef()

the message at block/genhd.c is as follows
void register_disk(struct gendisk *disk)
{

struct device *ddev = disk_to_dev(disk);

struct block_device *bdev;

struct disk_part_iter piter;

struct hd_struct *part;

int err;

ddev->parent = disk->driverfs_dev;

dev_set_name(ddev, disk->disk_name);

delay uevents, until we scanned partition table

dev_set_uevent_suppress(ddev, 1);

if (device_add(ddev))

return;

527 if (!sysfs_deprecated) {

err = sysfs_create_link(block_depr, &ddev->kobj,

kobject_name(&ddev->kobj));

if (err) {

device_del(ddev);

return;
}

}

}
nt main()
{
printf(“hello\n”);
return 0;
/*
Aug 5 10:03:45 zaffer kernel:
[ 5936.683085] Begin : start

Aug 5 10:03:45 zaffer kernel:
[ 5936.683087] HELLO KERNEL

Aug 5 10:03:45 zaffer kernel:
[ 5936.683090] Registration Sucessful

Aug 5 10:03:45 zaffer kernel:
[ 5936.683091]
Aug 5 10:03:45 zaffer kernel:
[ 5936.683093] Major no is 252

Aug 5 10:03:45 zaffer kernel: [ 5936.683134] Memory allocation of block device sucessful

Aug 5 10:03:45 zaffer kernel: [ 5936.683135]

Aug 5 10:03:45 zaffer kernel: [ 5936.683136] after spin_lock

Aug 5 10:03:45 zaffer kernel: [ 5936.683137]

Aug 5 10:03:45 zaffer kernel: [ 5936.683145] alloc_disk sucessful

Aug 5 10:03:45 zaffer kernel: [ 5936.683146]

Aug 5 10:03:45 zaffer kernel: [ 5936.683161] sbullmajor

Aug 5 10:03:45 zaffer kernel: [ 5936.683162]

Aug 5 10:03:45 zaffer kernel: [ 5936.683163] sbullminor

Aug 5 10:03:45 zaffer kernel: [ 5936.683164]

Aug 5 10:03:45 zaffer kernel: [ 5936.683165] first_minor

Aug 5 10:03:45 zaffer kernel: [ 5936.683166]

Aug 5 10:03:45 zaffer kernel: [ 5936.683167] file_operations

Aug 5 10:03:45 zaffer kernel: [ 5936.683168]

Aug 5 10:03:45 zaffer kernel: [ 5936.683169] Queue

Aug 5 10:03:45 zaffer kernel: [ 5936.683169]

Aug 5 10:03:45 zaffer kernel: [ 5936.683170] private_data

Aug 5 10:03:45 zaffer kernel: [ 5936.683171]

Aug 5 10:03:45 zaffer kernel: [ 5936.683172] sbulla

Aug 5 10:03:45 zaffer kernel: [ 5936.683173]

Aug 5 10:03:45 zaffer kernel: [ 5936.683174] set_capacity

Aug 5 10:03:45 zaffer kernel: [ 5936.683175]

Aug 5 10:03:45 zaffer kernel: [ 5936.683176] ————[ cut here ]————
Aug 5 10:03:45 zaffer kernel: [ 5936.683183] WARNING: at block/genhd.c:527 add_disk+0x4d/0xef()

the message at block/genhd.c is as follows
void register_disk(struct gendisk *disk)
{

struct device *ddev = disk_to_dev(disk);

struct block_device *bdev;

struct disk_part_iter piter;

struct hd_struct *part;

int err;

ddev->parent = disk->driverfs_dev;

dev_set_name(ddev, disk->disk_name);

delay uevents, until we scanned partition table

dev_set_uevent_suppress(ddev, 1);

if (device_add(ddev))

return;

527 if (!sysfs_deprecated) {

err = sysfs_create_link(block_depr, &ddev->kobj,

kobject_name(&ddev->kobj));

if (err) {

device_del(ddev);

return;
}

}

}

#ifdef DEBUG
printk(KERN_INFO”In %s function\n”,__func__);
#endif

#ifdef DEBUG
printk(KERN_INFO”nalue of cmd is %d\n”,cmd);
#endif

if (_IOC_TYPE(cmd) != MAGIC_NUMBER)
{
#ifdef DEBUG
printk(KERN_INFO” MAGIC value of err is %d\n”,err);
#endif
return -ENOTTY;
}
if (_IOC_NR(cmd) > STEPPER_MOTOR_MAX_NR)
{
#ifdef DEBUG
printk(KERN_INFO”STEPPER value of err is %d\n”,err);
#endif
return -ENOTTY;
}

if (_IOC_DIR(cmd) & _IOC_READ){
err = !access_ok(VERIFY_WRITE, (void __user *)arg, _IOC_SIZE(cmd));
#ifdef DEBUG
printk(KERN_INFO” IOC_READ value of err is %d\n”,err);
#endif
}

else if (_IOC_DIR(cmd) & _IOC_WRITE){
err = !access_ok(VERIFY_READ, (void __user *)arg, _IOC_SIZE(cmd));
#ifdef DEBUG
printk(KERN_INFO”IOC_WRITE value of err is %d\n”,err);
#endif
}
if (err) return -EFAULT;

switch(cmd)
{
case(MOTOR_START):
{
#ifdef DEBUG
printk(KERN_INFO”motor start\n”);
#endif
outb(0×01,DATA);
outb(0×04,DATA);
}
case(MOTOR_STOP):
{
outb(0×00,DATA);
}
case(ANTICLOCKWISE):
{
#ifdef DEBUG
printk(KERN_INFO”anticlockwise\n”);
#endif
outb(0xF1,DATA);
ssleep(300);
outb(0xF2,DATA);
ssleep(300);
outb(0xF4,DATA);
ssleep(300);
outb(0xF8,DATA);
ssleep(300);
}
case(CLOCKWISE):
{
#ifdef DEBUG
printk(KERN_INFO”clockwise\n”);
#endif
outb(0xF8,DATA);
ssleep(300);
outb(0xF4,DATA);
ssleep(300);
outb(0xF2,DATA);
ssleep(300);
outb(0xF1,DATA);
ssleep(300);
}
case(INCREASE_SPEED):
{

#ifdef DEBUG
printk(KERN_INFO”increase speed\n”);
#endif
outb(0xF8,DATA);
ssleep(30000);
outb(0xF4,DATA);
ssleep(30000);
outb(0xF2,DATA);
ssleep(30000);
outb(0xF1,DATA);
}
case(INCREASE_SPEED):
{

#ifdef DEBUG
printk(KERN_INFO”increase speed\n”);
#endif
outb(0xF8,DATA);
ssleep(30000);
outb(0xF4,DATA);
ssleep(30000);
outb(0xF2,DATA);
ssleep(30000);
outb(0xF1,DATA);
ssleep(30000);
}

case(DECREASE_SPEED):
{
#ifdef DEBUG
printk(KERN_INFO”decrease speed\n”);
#endif

outb(0xF8,DATA);
ssleep(3);
outb(0xF4,DATA);
outb(0xF2,DATA);
ssleep(3);
outb(0xF1,DATA);
ssleep(3);
}
default:
{

#ifdef DEBUG
printk(KERN_INFO”value of cmd is %d\n”,cmd);
#endif

}
}

return 0;
}
……………..
when i press any no it reflects the same no in the ioctl but when it goes in switch case the value of cmd is something 0 ………plz explain…..i tested on 2 systems but same result

scullread(……..)
{declare vriables……struct sculldev *lsculldev;
wait_for_completion(lsculldev->my_completion);
………….
}
scull_write(………..)
{
declare vriables……struct sculldev *lsculldev;
……………………………………..
…………code……………………
…………code…………………..
complete(&lsculldev->my_completion);
return 0;
}
HOWEVER WHEN I RUN THE APPLICATION THE SYSTEM CRASHES.
the messages in var/log/messages is
BUG: sleeping function called from invalid context at arch/x86/mm fault.c
in_atomic(): 0, irqs_disabled:1, pid 2207

i would appreciate if any one could help

HEADER FILE
#include
#include
#include
#include
#include
#include
#include

#define SCULL_MAJOR 0

#define SCULL_MINOR 0

#define device_name “ZAFFER”

#define device_no 1

#define NO_OF_DEVICES 1

#ifndef DEBUG
#define DEBUG
#endif

//………………defining file_operations……………

int scull_open(struct inode*,struct file*);
//int scullrelease(struct inode*, struct file* );

//……………….end of functions…………………..

//…………………….major mainor…………………

static int scull_major = SCULL_MAJOR;
static int scull_minor = SCULL_MINOR;
//………….. ……………………….
//……………….structs and declerations…………..
const struct file_operations fops={
.open = scull_open,
// release: scullrelease
};
struct Scull_dev{

struct cdev cdev;

};
struct Scull_dev *sculldev;

//………………………end of declerations………….
MODULE_AUTHOR(“Zaffer”);
MODULE_LICENSE(“GPL”);
//…………………………………………………..
55,1

LKO.C
int reg;
printk(KERN_INFO “Begin : %s\n”,__func__);
printk(KERN_INFO” HELLO KERNEL”);
printk(KERN_INFO “GREAT”);
if(scull_major)
{
dev=MKDEV(scull_major,scull_minor);
reg=register_chrdev_region(dev,scull_major,device_name);
}
else
{

reg=alloc_chrdev_region(&dev,scull_major,device_no,device_name);
scull_major=MAJOR(dev);
}
if(regcdev.owner=THIS_MODULE;
sculldev->cdev.ops=&fops;
cdev_init(&(sculldev->cdev),&fops );
int scull_open(struct inode *inode, struct file *filp)
{
// #ifdef DEBUG
// printk(KERN_INFO “open function performed sucessfully\n”);
- // #endif
return 0;
}
cdev_add(&(sculldev->cdev),dev,1);
return 0;
}
void __exit release(void)
{
#ifdef DEBUG
printk(KERN_INFO “exit : %s\n”,__func__);
#endif

printk(KERN_INFO “BYE KERNEL”);
unregister_chrdev_region(dev,device_no);
kfree(sculldev);
cdev_del(&(sculldev->cdev));

}

#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>

struct linklist{
char **data;
struct linklist *next;
}*start,*temp,*last;
int main()
{
int i,j,m,l;
int quantams;
char y;
start=(struct linklist*)malloc(sizeof(struct linklist));
temp=(struct linklist*)malloc(sizeof(struct linklist));
//last->data=malloc(sizeof(char*)*);
//printf(“enter the dat in the first node\n”);
start->next=NULL;
//scanf(” %d”,&start->data);
temp=start;
j=0;
printf(“do u wana linklist press y\n”);
scanf(” %c”,&y);
while(y==’y’||y==’Y’)

{
printf(“this is %d node\n”,j+1);
last=(struct linklist*)malloc(sizeof(struct linklist));
last->data=(char **)malloc(sizeof(char *));
for(m=0;m<=1;m++)
{
last->data[m]=(char*)malloc(sizeof(char));

for(l=0;l<=1;l++)
{
printf(“row no %d: column no %d”,m,l);
printf(” enter the information\n”);
scanf(“%d”,&quantams);
//last->data[m][l]=quantams;
*(*(last->data+m)+l)=quantams;
}
}
last->next=NULL;
printf(“last->next=NULL\n”);
temp->next=last;
printf(“temp->next=last\n”);
temp=last;
printf(“temp=last\n”);
j++;
printf(“do you wana continue press y or Y\n”);
scanf(” %c”,&y);
}
j=0;
temp=start;
while(temp->next!=NULL)
{
printf(“this is %d node\n”,j);
for(m=0;m<=1;m++)
{

for(l=0;l<=1;l++)
{
printf(“row no %d :: column no %d”,m,l);
printf(” %d\n”,*(*(temp->data+m)+l));
}
}
temp=temp->next;
j++;
}
return 0;
}