--- drivers/usb/printer.c.orig 2004-03-05 17:29:50.238186624 +0000 +++ drivers/usb/printer.c 2004-03-05 17:35:05.346282912 +0000 @@ -604,14 +604,16 @@ static ssize_t usblp_write(struct file * { DECLARE_WAITQUEUE(wait, current); struct usblp *usblp = file->private_data; - int timeout, err = 0; + int timeout, err = 0, transfer_length = 0; size_t writecount = 0; while (writecount < count) { if (!usblp->wcomplete) { barrier(); - if (file->f_flags & O_NONBLOCK) - return -EAGAIN; + if (file->f_flags & O_NONBLOCK) { + writecount += transfer_length; + return writecount ? writecount : -EAGAIN; + } timeout = USBLP_WRITE_TIMEOUT; add_wait_queue(&usblp->wait, &wait); @@ -655,27 +657,36 @@ static ssize_t usblp_write(struct file * continue; } - writecount += usblp->writeurb->transfer_buffer_length; - usblp->writeurb->transfer_buffer_length = 0; - + /* We must increment writecount here, and not at the + * end of the loop. Otherwise, the final loop iteration may + * be skipped, leading to incomplete printer output. + */ + writecount += transfer_length; if (writecount == count) { up (&usblp->sem); break; } - usblp->writeurb->transfer_buffer_length = (count - writecount) < USBLP_BUF_SIZE ? - (count - writecount) : USBLP_BUF_SIZE; + transfer_length = count - writecount; + if(transfer_length > USBLP_BUF_SIZE) + transfer_length = USBLP_BUF_SIZE; + + usblp->writeurb->transfer_buffer_length = transfer_length; - if (copy_from_user(usblp->writeurb->transfer_buffer, buffer + writecount, - usblp->writeurb->transfer_buffer_length)) { + if (copy_from_user(usblp->writeurb->transfer_buffer, + buffer + writecount, transfer_length)) { up(&usblp->sem); return writecount ? writecount : -EFAULT; } usblp->writeurb->dev = usblp->dev; usblp->wcomplete = 0; - if (usb_submit_urb(usblp->writeurb)) { - count = -EIO; + err = usb_submit_urb(usblp->writeurb); + if (err) { + if (err != -ENOMEM) + count = -EIO; + else + count = writecount ? writecount : -ENOMEM; up (&usblp->sem); break; }