Onsdag den 22. februar 2012 12:35:16 skrev Mayank Rana:

I have few queries related to using Line Discipline.

1. I understand that line discipline can be changed from user space
application by opening the device and doing ioctl with required Line
Discipline ID. Is it possible to do the same from kernel module who
would be communicating with that line discipline ?

2. Is it way to set default line discipline for particular tty device
to required Line Discipline instead of N_TTY one ?

Appreciate your help on this.

I've earlier done something like this :


        /* Attach line discipline to the uctrl tty */
        set_fs(get_ds());
        ret = put_user(N_PS3D, &ldiscNum);
        if (ret != 0) {
                PSDEBUG(debuglevel, "Leaving, EFAULT\n");
                return -EFAULT;
        } else {
                set_fs(KERNEL_DS);
                ret = uctrl_file->f_op->unlocked_ioctl(uctrl_file, TIOCSETD, (unsigned long)&ldiscNum);

                /*
                 * Decrement use count since setting the line descipline triggers a call to 'n_ps3d_tty_open'
                 * which increments the use count making it impossible to only the module without --force
                 */
                module_put(THIS_MODULE);

                if (ret < 0) {
                        PSKERR(debuglevel, "failed with n_tty_ioctl()\n");
                        return -EFAULT;
                }
        }
        set_fs(old_fs);



-- 
Søren Holm
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