tty: remove TTY_MAGIC

According to Greg, in the context of magic numbers as defined in
magic-number.rst, "the tty layer should not need this and I'll gladly
take patches"

Acked-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Ref: https://lore.kernel.org/linux-doc/YyMlovoskUcHLEb7@kroah.com/
Link: https://lore.kernel.org/r/476d024cd6b04160a5de381ea2b9856b60088cbd.1663288066.git.nabijaczleweli@nabijaczleweli.xyz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

7 files changed, 0 insertions, 24 deletions

diff --git a/Documentation/process/magic-number.rst b/Documentation/process/magic-number.rst
index f5ba36e96461..b4c7ec61437e 100644
--- a/Documentation/process/magic-number.rst
+++ b/Documentation/process/magic-number.rst
@@ -84,7 +84,6 @@ SLIP_MAGIC            0x5302           slip                     ``drivers/net/sl
 STRIP_MAGIC           0x5303           strip                    ``drivers/net/strip.c``
 SIXPACK_MAGIC         0x5304           sixpack                  ``drivers/net/hamradio/6pack.h``
 AX25_MAGIC            0x5316           ax_disp                  ``drivers/net/mkiss.h``
-TTY_MAGIC             0x5401           tty_struct               ``include/linux/tty.h``
 MGSL_MAGIC            0x5401           mgsl_info                ``drivers/char/synclink.c``
 TTY_DRIVER_MAGIC      0x5402           tty_driver               ``include/linux/tty_driver.h``
 MGSLPC_MAGIC          0x5402           mgslpc_info              ``drivers/char/pcmcia/synclink_cs.c``
diff --git a/Documentation/translations/it_IT/process/magic-number.rst b/Documentation/translations/it_IT/process/magic-number.rst
index f452fafb1e84..bcb23384fefd 100644
--- a/Documentation/translations/it_IT/process/magic-number.rst
+++ b/Documentation/translations/it_IT/process/magic-number.rst
@@ -90,7 +90,6 @@ SLIP_MAGIC            0x5302           slip                     ``drivers/net/sl
 STRIP_MAGIC           0x5303           strip                    ``drivers/net/strip.c``
 SIXPACK_MAGIC         0x5304           sixpack                  ``drivers/net/hamradio/6pack.h``
 AX25_MAGIC            0x5316           ax_disp                  ``drivers/net/mkiss.h``
-TTY_MAGIC             0x5401           tty_struct               ``include/linux/tty.h``
 MGSL_MAGIC            0x5401           mgsl_info                ``drivers/char/synclink.c``
 TTY_DRIVER_MAGIC      0x5402           tty_driver               ``include/linux/tty_driver.h``
 MGSLPC_MAGIC          0x5402           mgslpc_info              ``drivers/char/pcmcia/synclink_cs.c``
diff --git a/Documentation/translations/zh_CN/process/magic-number.rst b/Documentation/translations/zh_CN/process/magic-number.rst
index 42f0635ca70a..6250087d36c5 100644
--- a/Documentation/translations/zh_CN/process/magic-number.rst
+++ b/Documentation/translations/zh_CN/process/magic-number.rst
@@ -73,7 +73,6 @@ SLIP_MAGIC            0x5302           slip                     ``drivers/net/sl
 STRIP_MAGIC           0x5303           strip                    ``drivers/net/strip.c``
 SIXPACK_MAGIC         0x5304           sixpack                  ``drivers/net/hamradio/6pack.h``
 AX25_MAGIC            0x5316           ax_disp                  ``drivers/net/mkiss.h``
-TTY_MAGIC             0x5401           tty_struct               ``include/linux/tty.h``
 MGSL_MAGIC            0x5401           mgsl_info                ``drivers/char/synclink.c``
 TTY_DRIVER_MAGIC      0x5402           tty_driver               ``include/linux/tty_driver.h``
 MGSLPC_MAGIC          0x5402           mgslpc_info              ``drivers/char/pcmcia/synclink_cs.c``
diff --git a/Documentation/translations/zh_TW/process/magic-number.rst b/Documentation/translations/zh_TW/process/magic-number.rst
index ae321a9aaece..fd169d760bbd 100644
--- a/Documentation/translations/zh_TW/process/magic-number.rst
+++ b/Documentation/translations/zh_TW/process/magic-number.rst
@@ -76,7 +76,6 @@ SLIP_MAGIC            0x5302           slip                     ``drivers/net/sl
 STRIP_MAGIC           0x5303           strip                    ``drivers/net/strip.c``
 SIXPACK_MAGIC         0x5304           sixpack                  ``drivers/net/hamradio/6pack.h``
 AX25_MAGIC            0x5316           ax_disp                  ``drivers/net/mkiss.h``
-TTY_MAGIC             0x5401           tty_struct               ``include/linux/tty.h``
 MGSL_MAGIC            0x5401           mgsl_info                ``drivers/char/synclink.c``
 TTY_DRIVER_MAGIC      0x5402           tty_driver               ``include/linux/tty_driver.h``
 MGSLPC_MAGIC          0x5402           mgslpc_info              ``drivers/char/pcmcia/synclink_cs.c``
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 571c94c81477..1da743155245 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -170,7 +170,6 @@ static void free_tty_struct(struct tty_struct *tty)
 	tty_ldisc_deinit(tty);
 	put_device(tty->dev);
 	kvfree(tty->write_buf);
-	tty->magic = 0xDEADDEAD;
 	kfree(tty);
 }
 
@@ -265,11 +264,6 @@ static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
 			imajor(inode), iminor(inode), routine);
 		return 1;
 	}
-	if (tty->magic != TTY_MAGIC) {
-		pr_warn("(%d:%d): %s: bad magic number\n",
-			imajor(inode), iminor(inode), routine);
-		return 1;
-	}
 #endif
 	return 0;
 }
@@ -1533,7 +1527,6 @@ static void release_one_tty(struct work_struct *work)
 	if (tty->ops->cleanup)
 		tty->ops->cleanup(tty);
 
-	tty->magic = 0;
 	tty_driver_kref_put(driver);
 	module_put(owner);
 
@@ -3093,7 +3086,6 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
 		return NULL;
 
 	kref_init(&tty->kref);
-	tty->magic = TTY_MAGIC;
 	if (tty_ldisc_init(tty)) {
 		kfree(tty);
 		return NULL;
diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 393518a24cfe..784e46a0a3b1 100644
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -14,8 +14,6 @@
 
 void tty_lock(struct tty_struct *tty)
 {
-	if (WARN(tty->magic != TTY_MAGIC, "L Bad %p\n", tty))
-		return;
 	tty_kref_get(tty);
 	mutex_lock(&tty->legacy_mutex);
 }
@@ -25,8 +23,6 @@ int tty_lock_interruptible(struct tty_struct *tty)
 {
 	int ret;
 
-	if (WARN(tty->magic != TTY_MAGIC, "L Bad %p\n", tty))
-		return -EIO;
 	tty_kref_get(tty);
 	ret = mutex_lock_interruptible(&tty->legacy_mutex);
 	if (ret)
@@ -36,8 +32,6 @@ int tty_lock_interruptible(struct tty_struct *tty)
 
 void tty_unlock(struct tty_struct *tty)
 {
-	if (WARN(tty->magic != TTY_MAGIC, "U Bad %p\n", tty))
-		return;
 	mutex_unlock(&tty->legacy_mutex);
 	tty_kref_put(tty);
 }
diff --git a/include/linux/tty.h b/include/linux/tty.h
index ae41893f8653..730c3301d710 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -122,8 +122,6 @@ struct tty_operations;
 /**
  * struct tty_struct - state associated with a tty while open
  *
- * @magic: magic value set early in @alloc_tty_struct to %TTY_MAGIC, for
- *	   debugging purposes
  * @kref: reference counting by tty_kref_get() and tty_kref_put(), reaching zero
  *	  frees the structure
  * @dev: class device or %NULL (e.g. ptys, serdev)
@@ -193,7 +191,6 @@ struct tty_operations;
  * &struct tty_port.
  */
 struct tty_struct {
-	int	magic;
 	struct kref kref;
 	struct device *dev;
 	struct tty_driver *driver;
@@ -260,9 +257,6 @@ struct tty_file_private {
 	struct list_head list;
 };
 
-/* tty magic number */
-#define TTY_MAGIC		0x5401
-
 /**
  * DOC: TTY Struct Flags
  *