linux block driver error while reading data
 

hi
i am writing sample block driver
while reading data i am getting below error

i am not getting what is this error

plz help


BUG: sleeping function called from invalid context at kernel/sched.c:4684
in_atomic():0, irqs_disabled():1
Pid: 5364, comm: test_buf Not tainted 2.6.27.42 #1
[<c041f1d4>] __might_sleep+0xae/0xb3
[<c063ae43>] wait_for_common+0x1f/0x117
[<c0584bd3>] ? usb_submit_urb+0x1e1/0x1fd
[<c063af99>] wait_for_completion_timeout+0xd/0xf
[<c05856d5>] usb_start_wait_urb+0x58/0x95
[<c0410280>] ? p4_unreserve+0x1e/0x2c
[<c0585800>] usb_bulk_msg+0xee/0xf5
[<c0410280>] ? p4_unreserve+0x1e/0x2c
[<f8fc48dd>] test_request+0x1d6/0x268 [test_driver_usb]
[<c04ee9e7>] __generic_unplug_device+0x1d/0x20
[<c04eec67>] generic_unplug_device+0x21/0x3a
[<c04ed77d>] blk_unplug+0x51/0x58
[<c04ed78f>] blk_backing_dev_unplug+0xb/0xd
[<c04a3e65>] block_sync_page+0x32/0x34
[<c0464a6d>] sync_page+0x31/0x3a
[<c0464a7e>] sync_page_killable+0x8/0x2e
[<c063b10b>] __wait_on_bit_lock+0x34/0x70
[<c0464a76>] ? sync_page_killable+0x0/0x2e
[<c04649a7>] __lock_page_killable+0x7b/0x83
[<c043b272>] ? wake_bit_function+0x0/0x43
[<c0466553>] generic_file_aio_read+0x385/0x588
[<c0487242>] do_sync_read+0xab/0xe9
[<c043b23f>] ? autoremove_wake_function+0x0/0x33
[<c04db692>] ? selinux_file_permission+0xff/0x105
[<c04d49be>] ? security_file_permission+0xf/0x11
[<c0487197>] ? do_sync_read+0x0/0xe9
[<c0487bdb>] vfs_read+0x87/0x12b
[<c0487d18>] sys_read+0x3b/0x60
[<c0403a2f>] sysenter_do_call+0x12/0x2f
[<c0630000>] ? nv_msi_ht_cap_quirk+0xe/0xe5
=======================

Would you mind showing the code you are writing ?

hi
this my read function which is getting called from request function

static ssize_t data_read(struct test_usb *dev, char *buffer, size_t count)
{
printk("*** SARD: Inside Read Function ***\n");

int retval;
int bytes_read;
int rcvbulkpipe = usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr);

int timeout = jiffies + (HZ*10);
if (!dev->interface) { // disconnect() was called
retval = -ENODEV;
return retval;
}

dev->usb_buffer = "Test Application";
printk("usb buffer:= %s\n", dev->usb_buffer);

retval = usb_bulk_msg(dev->udev, rcvbulkpipe, dev->usb_buffer, min(strlen(dev->usb_buffer), count), &bytes_read, timeout);

info("usbDIO: Read retval: %d, count: %lu, bytes Read: %d", retval, count, bytes_read);

if (retval == 0)
{
if (copy_to_user(buffer, dev->usb_buffer, bytes_read))
retval = -EFAULT;
else{
retval = bytes_read;
printk("bufer:= %s\n", buffer);
printk("usb_buffer:= %s\n", dev->usb_buffer);
}
}
else
{
if (retval == -ETIMEDOUT)
{
info("usbDIO: Read timeout");
retval = 0;
}
}
return retval;

}

//request function
static void data_transfer(struct test_usb *dev_t, unsigned long sector, unsigned long nsect, char *buffer, int write)
{
printk("*** Archana: Inside data_transfer ***\n");

unsigned long offset = sector * blkdev_sect_size;
unsigned long nbytes = nsect * blkdev_sect_size;

if ((offset + nbytes) > dev_t->buffer_size) {
printk (KERN_NOTICE "Beyond-end write (%ld %ld)\n", offset, nbytes);
return;
}

if (write)
{
data_write();
}
else
{
data_read(dev_t, buffer, nbytes);
}

}


..

when control goes to read function i am getting above mentioned error
and it is not reading anything

if u know anything plz share

scsi command for linux block driver
 

hi
i am writing block deriver for usb device in linux

i want to read data from usb device
i already opened the handle for the usb device

now i need to send scsi command to usb device to make it work

but i dont have knowledge about scsi commands and how to use them

now i need to know which scsi command i need to pass to the usb device
and how can i pass that command to usb device

Read these links carefully, some other people have faced the same bug

http://www.mail-archive.com/utrace-d.../msg00391.html

http://www.mail-archive.com/utrace-d.../msg00392.html

I have merged two closely related threads.

Please do not keep starting new threads for the same basic question---thank you.