| 1 | |
| 2 | #include <linux/types.h>
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| 3 | #include <linux/errno.h>
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| 4 | #include <linux/tty.h>
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| 5 | #include <linux/module.h>
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| 6 |
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| 7 | |
| 8 | * n_null.c - Null line discipline used in the failure path
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| 9 | *
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| 10 | * Copyright (C) Intel 2017
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| 11 |
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| 12 |
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| 13 | static ssize_t n_null_read(struct tty_struct *tty, struct file *file, u8 *buf,
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| 14 | size_t nr, void **cookie, unsigned long offset)
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| 15 | {
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| 16 | return -EOPNOTSUPP;
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| 17 | }
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| 18 |
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| 19 | static ssize_t n_null_write(struct tty_struct *tty, struct file *file,
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| 20 | const u8 *buf, size_t nr)
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| 21 | {
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| 22 | return -EOPNOTSUPP;
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| 23 | }
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| 24 |
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| 25 | static struct tty_ldisc_ops null_ldisc = {
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| 26 | .owner = THIS_MODULE,
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| 27 | .num = N_NULL,
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| 28 | .name = "n_null",
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| 29 | .read = n_null_read,
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| 30 | .write = n_null_write,
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| 31 | };
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| 32 |
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| 33 | static int __init n_null_init(void)
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| 34 | {
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| 35 | BUG_ON(tty_register_ldisc(&null_ldisc));
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| 36 | return 0;
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| 37 | }
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| 38 |
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| 39 | static void __exit n_null_exit(void)
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| 40 | {
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| 41 | tty_unregister_ldisc(&null_ldisc);
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| 42 | }
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| 43 |
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| 44 | module_init(n_null_init);
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| 45 | module_exit(n_null_exit);
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| 46 |
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| 47 | MODULE_LICENSE("GPL");
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| 48 | MODULE_AUTHOR("Alan Cox");
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| 49 | MODULE_ALIAS_LDISC(N_NULL);
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| 50 | MODULE_DESCRIPTION("Null ldisc driver");
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