mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-11-01 17:08:10 +00:00
Code Issues Releases Wiki Activity
linux-stable/include/linux/tty.h
Greg Kroah-Hartman ebf05c7dc9 tty: shrink the size of struct tty_struct by 40 bytes 
It's been a long time since anyone has looked at what struct tty_struct
looks like in memory, turns out there was a ton of holes.

So move things around a bit, change one variable (closing) from being an
int to a bool (it is only being tested for 0/1), and we end up saving 40
bytes per structure overall on x86-64 systems.

Before this patch:
	/* size: 696, cachelines: 11, members: 37 */
	/* sum members: 665, holes: 8, sum holes: 31 */
	/* forced alignments: 2, forced holes: 1, sum forced holes: 4 */
	/* last cacheline: 56 bytes */

After this change:
	/* size: 656, cachelines: 11, members: 37 */
	/* sum members: 654, holes: 1, sum holes: 2 */
	/* forced alignments: 2 */
	/* last cacheline: 16 bytes */

Cc: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/2023082519-cobbler-unholy-8d1f@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-08-27 11:47:44 +02:00

518 lines
18 KiB
C
Raw Blame History

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_TTY_H
#define _LINUX_TTY_H
#include <linux/fs.h>
#include <linux/major.h>
#include <linux/termios.h>
#include <linux/workqueue.h>
#include <linux/tty_buffer.h>
#include <linux/tty_driver.h>
#include <linux/tty_ldisc.h>
#include <linux/tty_port.h>
#include <linux/mutex.h>
#include <linux/tty_flags.h>
#include <uapi/linux/tty.h>
#include <linux/rwsem.h>
#include <linux/llist.h>
/*
* (Note: the *_driver.minor_start values 1, 64, 128, 192 are
* hardcoded at present.)
*/
#define NR_UNIX98_PTY_DEFAULT 4096 /* Default maximum for Unix98 ptys */
#define NR_UNIX98_PTY_RESERVE 1024 /* Default reserve for main devpts */
#define NR_UNIX98_PTY_MAX (1 << MINORBITS) /* Absolute limit */
/*
* This character is the same as _POSIX_VDISABLE: it cannot be used as
* a c_cc[] character, but indicates that a particular special character
* isn't in use (eg VINTR has no character etc)
*/
#define __DISABLED_CHAR '\0'
#define INTR_CHAR(tty) ((tty)->termios.c_cc[VINTR])
#define QUIT_CHAR(tty) ((tty)->termios.c_cc[VQUIT])
#define ERASE_CHAR(tty) ((tty)->termios.c_cc[VERASE])
#define KILL_CHAR(tty) ((tty)->termios.c_cc[VKILL])
#define EOF_CHAR(tty) ((tty)->termios.c_cc[VEOF])
#define TIME_CHAR(tty) ((tty)->termios.c_cc[VTIME])
#define MIN_CHAR(tty) ((tty)->termios.c_cc[VMIN])
#define SWTC_CHAR(tty) ((tty)->termios.c_cc[VSWTC])
#define START_CHAR(tty) ((tty)->termios.c_cc[VSTART])
#define STOP_CHAR(tty) ((tty)->termios.c_cc[VSTOP])
#define SUSP_CHAR(tty) ((tty)->termios.c_cc[VSUSP])
#define EOL_CHAR(tty) ((tty)->termios.c_cc[VEOL])
#define REPRINT_CHAR(tty) ((tty)->termios.c_cc[VREPRINT])
#define DISCARD_CHAR(tty) ((tty)->termios.c_cc[VDISCARD])
#define WERASE_CHAR(tty) ((tty)->termios.c_cc[VWERASE])
#define LNEXT_CHAR(tty) ((tty)->termios.c_cc[VLNEXT])
#define EOL2_CHAR(tty) ((tty)->termios.c_cc[VEOL2])
#define _I_FLAG(tty, f) ((tty)->termios.c_iflag & (f))
#define _O_FLAG(tty, f) ((tty)->termios.c_oflag & (f))
#define _C_FLAG(tty, f) ((tty)->termios.c_cflag & (f))
#define _L_FLAG(tty, f) ((tty)->termios.c_lflag & (f))
#define I_IGNBRK(tty) _I_FLAG((tty), IGNBRK)
#define I_BRKINT(tty) _I_FLAG((tty), BRKINT)
#define I_IGNPAR(tty) _I_FLAG((tty), IGNPAR)
#define I_PARMRK(tty) _I_FLAG((tty), PARMRK)
#define I_INPCK(tty) _I_FLAG((tty), INPCK)
#define I_ISTRIP(tty) _I_FLAG((tty), ISTRIP)
#define I_INLCR(tty) _I_FLAG((tty), INLCR)
#define I_IGNCR(tty) _I_FLAG((tty), IGNCR)
#define I_ICRNL(tty) _I_FLAG((tty), ICRNL)
#define I_IUCLC(tty) _I_FLAG((tty), IUCLC)
#define I_IXON(tty) _I_FLAG((tty), IXON)
#define I_IXANY(tty) _I_FLAG((tty), IXANY)
#define I_IXOFF(tty) _I_FLAG((tty), IXOFF)
#define I_IMAXBEL(tty) _I_FLAG((tty), IMAXBEL)
#define I_IUTF8(tty) _I_FLAG((tty), IUTF8)
#define O_OPOST(tty) _O_FLAG((tty), OPOST)
#define O_OLCUC(tty) _O_FLAG((tty), OLCUC)
#define O_ONLCR(tty) _O_FLAG((tty), ONLCR)
#define O_OCRNL(tty) _O_FLAG((tty), OCRNL)
#define O_ONOCR(tty) _O_FLAG((tty), ONOCR)
#define O_ONLRET(tty) _O_FLAG((tty), ONLRET)
#define O_OFILL(tty) _O_FLAG((tty), OFILL)
#define O_OFDEL(tty) _O_FLAG((tty), OFDEL)
#define O_NLDLY(tty) _O_FLAG((tty), NLDLY)
#define O_CRDLY(tty) _O_FLAG((tty), CRDLY)
#define O_TABDLY(tty) _O_FLAG((tty), TABDLY)
#define O_BSDLY(tty) _O_FLAG((tty), BSDLY)
#define O_VTDLY(tty) _O_FLAG((tty), VTDLY)
#define O_FFDLY(tty) _O_FLAG((tty), FFDLY)
#define C_BAUD(tty) _C_FLAG((tty), CBAUD)
#define C_CSIZE(tty) _C_FLAG((tty), CSIZE)
#define C_CSTOPB(tty) _C_FLAG((tty), CSTOPB)
#define C_CREAD(tty) _C_FLAG((tty), CREAD)
#define C_PARENB(tty) _C_FLAG((tty), PARENB)
#define C_PARODD(tty) _C_FLAG((tty), PARODD)
#define C_HUPCL(tty) _C_FLAG((tty), HUPCL)
#define C_CLOCAL(tty) _C_FLAG((tty), CLOCAL)
#define C_CIBAUD(tty) _C_FLAG((tty), CIBAUD)
#define C_CRTSCTS(tty) _C_FLAG((tty), CRTSCTS)
#define C_CMSPAR(tty) _C_FLAG((tty), CMSPAR)
#define L_ISIG(tty) _L_FLAG((tty), ISIG)
#define L_ICANON(tty) _L_FLAG((tty), ICANON)
#define L_XCASE(tty) _L_FLAG((tty), XCASE)
#define L_ECHO(tty) _L_FLAG((tty), ECHO)
#define L_ECHOE(tty) _L_FLAG((tty), ECHOE)
#define L_ECHOK(tty) _L_FLAG((tty), ECHOK)
#define L_ECHONL(tty) _L_FLAG((tty), ECHONL)
#define L_NOFLSH(tty) _L_FLAG((tty), NOFLSH)
#define L_TOSTOP(tty) _L_FLAG((tty), TOSTOP)
#define L_ECHOCTL(tty) _L_FLAG((tty), ECHOCTL)
#define L_ECHOPRT(tty) _L_FLAG((tty), ECHOPRT)
#define L_ECHOKE(tty) _L_FLAG((tty), ECHOKE)
#define L_FLUSHO(tty) _L_FLAG((tty), FLUSHO)
#define L_PENDIN(tty) _L_FLAG((tty), PENDIN)
#define L_IEXTEN(tty) _L_FLAG((tty), IEXTEN)
#define L_EXTPROC(tty) _L_FLAG((tty), EXTPROC)
struct device;
struct signal_struct;
struct tty_operations;
/**
* struct tty_struct - state associated with a tty while open
*
* @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)
* @driver: &struct tty_driver operating this tty
* @ops: &struct tty_operations of @driver for this tty (open, close, etc.)
* @index: index of this tty (e.g. to construct @name like tty12)
* @ldisc_sem: protects line discipline changes (@ldisc) -- lock tty not pty
* @ldisc: the current line discipline for this tty (n_tty by default)
* @atomic_write_lock: protects against concurrent writers, i.e. locks
* @write_cnt, @write_buf and similar
* @legacy_mutex: leftover from history (BKL -> BTM -> @legacy_mutex),
* protecting several operations on this tty
* @throttle_mutex: protects against concurrent tty_throttle_safe() and
* tty_unthrottle_safe() (but not tty_unthrottle())
* @termios_rwsem: protects @termios and @termios_locked
* @winsize_mutex: protects @winsize
* @termios: termios for the current tty, copied from/to @driver.termios
* @termios_locked: locked termios (by %TIOCGLCKTRMIOS and %TIOCSLCKTRMIOS
* ioctls)
* @name: name of the tty constructed by tty_line_name() (e.g. ttyS3)
* @flags: bitwise OR of %TTY_THROTTLED, %TTY_IO_ERROR, ...
* @count: count of open processes, reaching zero cancels all the work for
* this tty and drops a @kref too (but does not free this tty)
* @winsize: size of the terminal "window" (cf. @winsize_mutex)
* @flow: flow settings grouped together, see also @flow.unused
* @flow.lock: lock for @flow members
* @flow.stopped: tty stopped/started by stop_tty()/start_tty()
* @flow.tco_stopped: tty stopped/started by %TCOOFF/%TCOON ioctls (it has
* precedence over @flow.stopped)
* @flow.unused: alignment for Alpha, so that no members other than @flow.* are
* modified by the same 64b word store. The @flow's __aligned is
* there for the very same reason.
* @ctrl: control settings grouped together, see also @ctrl.unused
* @ctrl.lock: lock for @ctrl members
* @ctrl.pgrp: process group of this tty (setpgrp(2))
* @ctrl.session: session of this tty (setsid(2)). Writes are protected by both
* @ctrl.lock and @legacy_mutex, readers must use at least one of
* them.
* @ctrl.pktstatus: packet mode status (bitwise OR of %TIOCPKT_ constants)
* @ctrl.packet: packet mode enabled
* @ctrl.unused: alignment for Alpha, see @flow.unused for explanation
* @hw_stopped: not controlled by the tty layer, under @driver's control for CTS
* handling
* @receive_room: bytes permitted to feed to @ldisc without any being lost
* @flow_change: controls behavior of throttling, see tty_throttle_safe() and
* tty_unthrottle_safe()
* @link: link to another pty (master -> slave and vice versa)
* @fasync: state for %O_ASYNC (for %SIGIO); managed by fasync_helper()
* @write_wait: concurrent writers are waiting in this queue until they are
* allowed to write
* @read_wait: readers wait for data in this queue
* @hangup_work: normally a work to perform a hangup (do_tty_hangup()); while
* freeing the tty, (re)used to release_one_tty()
* @disc_data: pointer to @ldisc's private data (e.g. to &struct n_tty_data)
* @driver_data: pointer to @driver's private data (e.g. &struct uart_state)
* @files_lock: protects @tty_files list
* @tty_files: list of (re)openers of this tty (i.e. linked &struct
* tty_file_private)
* @closing: when set during close, n_tty processes only START & STOP chars
* @write_buf: temporary buffer used during tty_write() to copy user data to
* @write_cnt: count of bytes written in tty_write() to @write_buf
* @SAK_work: if the tty has a pending do_SAK, it is queued here
* @port: persistent storage for this device (i.e. &struct tty_port)
*
* All of the state associated with a tty while the tty is open. Persistent
* storage for tty devices is referenced here as @port and is documented in
* &struct tty_port.
*/
struct tty_struct {
struct kref kref;
int index;
struct device *dev;
struct tty_driver *driver;
struct tty_port *port;
const struct tty_operations *ops;
struct tty_ldisc *ldisc;
struct ld_semaphore ldisc_sem;
struct mutex atomic_write_lock;
struct mutex legacy_mutex;
struct mutex throttle_mutex;
struct rw_semaphore termios_rwsem;
struct mutex winsize_mutex;
struct ktermios termios, termios_locked;
char name[64];
unsigned long flags;
int count;
unsigned int receive_room;
struct winsize winsize;
struct {
spinlock_t lock;
bool stopped;
bool tco_stopped;
unsigned long unused[0];
} __aligned(sizeof(unsigned long)) flow;
struct {
struct pid *pgrp;
struct pid *session;
spinlock_t lock;
unsigned char pktstatus;
bool packet;
unsigned long unused[0];
} __aligned(sizeof(unsigned long)) ctrl;
bool hw_stopped;
bool closing;
int flow_change;
struct tty_struct *link;
struct fasync_struct *fasync;
wait_queue_head_t write_wait;
wait_queue_head_t read_wait;
struct work_struct hangup_work;
void *disc_data;
void *driver_data;
spinlock_t files_lock;
int write_cnt;
unsigned char *write_buf;
struct list_head tty_files;
#define N_TTY_BUF_SIZE 4096
struct work_struct SAK_work;
} __randomize_layout;
/* Each of a tty's open files has private_data pointing to tty_file_private */
struct tty_file_private {
struct tty_struct *tty;
struct file *file;
struct list_head list;
};
/**
* DOC: TTY Struct Flags
*
* These bits are used in the :c:member:`tty_struct.flags` field.
*
* So that interrupts won't be able to mess up the queues,
* copy_to_cooked must be atomic with respect to itself, as must
* tty->write. Thus, you must use the inline functions set_bit() and
* clear_bit() to make things atomic.
*
* TTY_THROTTLED
* Driver input is throttled. The ldisc should call
* :c:member:`tty_driver.unthrottle()` in order to resume reception when
* it is ready to process more data (at threshold min).
*
* TTY_IO_ERROR
* If set, causes all subsequent userspace read/write calls on the tty to
* fail, returning -%EIO. (May be no ldisc too.)
*
* TTY_OTHER_CLOSED
* Device is a pty and the other side has closed.
*
* TTY_EXCLUSIVE
* Exclusive open mode (a single opener).
*
* TTY_DO_WRITE_WAKEUP
* If set, causes the driver to call the
* :c:member:`tty_ldisc_ops.write_wakeup()` method in order to resume
* transmission when it can accept more data to transmit.
*
* TTY_LDISC_OPEN
* Indicates that a line discipline is open. For debugging purposes only.
*
* TTY_PTY_LOCK
* A flag private to pty code to implement %TIOCSPTLCK/%TIOCGPTLCK logic.
*
* TTY_NO_WRITE_SPLIT
* Prevent driver from splitting up writes into smaller chunks (preserve
* write boundaries to driver).
*
* TTY_HUPPED
* The TTY was hung up. This is set post :c:member:`tty_driver.hangup()`.
*
* TTY_HUPPING
* The TTY is in the process of hanging up to abort potential readers.
*
* TTY_LDISC_CHANGING
* Line discipline for this TTY is being changed. I/O should not block
* when this is set. Use tty_io_nonblock() to check.
*
* TTY_LDISC_HALTED
* Line discipline for this TTY was stopped. No work should be queued to
* this ldisc.
*/
#define TTY_THROTTLED 0
#define TTY_IO_ERROR 1
#define TTY_OTHER_CLOSED 2
#define TTY_EXCLUSIVE 3
#define TTY_DO_WRITE_WAKEUP 5
#define TTY_LDISC_OPEN 11
#define TTY_PTY_LOCK 16
#define TTY_NO_WRITE_SPLIT 17
#define TTY_HUPPED 18
#define TTY_HUPPING 19
#define TTY_LDISC_CHANGING 20
#define TTY_LDISC_HALTED 22
static inline bool tty_io_nonblock(struct tty_struct *tty, struct file *file)
{
return file->f_flags & O_NONBLOCK ||
test_bit(TTY_LDISC_CHANGING, &tty->flags);
}
static inline bool tty_io_error(struct tty_struct *tty)
{
return test_bit(TTY_IO_ERROR, &tty->flags);
}
static inline bool tty_throttled(struct tty_struct *tty)
{
return test_bit(TTY_THROTTLED, &tty->flags);
}
#ifdef CONFIG_TTY
void tty_kref_put(struct tty_struct *tty);
struct pid *tty_get_pgrp(struct tty_struct *tty);
void tty_vhangup_self(void);
void disassociate_ctty(int priv);
dev_t tty_devnum(struct tty_struct *tty);
void proc_clear_tty(struct task_struct *p);
struct tty_struct *get_current_tty(void);
/* tty_io.c */
int __init tty_init(void);
const char *tty_name(const struct tty_struct *tty);
struct tty_struct *tty_kopen_exclusive(dev_t device);
struct tty_struct *tty_kopen_shared(dev_t device);
void tty_kclose(struct tty_struct *tty);
int tty_dev_name_to_number(const char *name, dev_t *number);
#else
static inline void tty_kref_put(struct tty_struct *tty)
{ }
static inline struct pid *tty_get_pgrp(struct tty_struct *tty)
{ return NULL; }
static inline void tty_vhangup_self(void)
{ }
static inline void disassociate_ctty(int priv)
{ }
static inline dev_t tty_devnum(struct tty_struct *tty)
{ return 0; }
static inline void proc_clear_tty(struct task_struct *p)
{ }
static inline struct tty_struct *get_current_tty(void)
{ return NULL; }
/* tty_io.c */
static inline int __init tty_init(void)
{ return 0; }
static inline const char *tty_name(const struct tty_struct *tty)
{ return "(none)"; }
static inline struct tty_struct *tty_kopen_exclusive(dev_t device)
{ return ERR_PTR(-ENODEV); }
static inline void tty_kclose(struct tty_struct *tty)
{ }
static inline int tty_dev_name_to_number(const char *name, dev_t *number)
{ return -ENOTSUPP; }
#endif
extern struct ktermios tty_std_termios;
int vcs_init(void);
extern const struct class tty_class;
/**
* tty_kref_get - get a tty reference
* @tty: tty device
*
* Return a new reference to a tty object. The caller must hold
* sufficient locks/counts to ensure that their existing reference cannot
* go away
*/
static inline struct tty_struct *tty_kref_get(struct tty_struct *tty)
{
if (tty)
kref_get(&tty->kref);
return tty;
}
const char *tty_driver_name(const struct tty_struct *tty);
void tty_wait_until_sent(struct tty_struct *tty, long timeout);
void stop_tty(struct tty_struct *tty);
void start_tty(struct tty_struct *tty);
void tty_write_message(struct tty_struct *tty, char *msg);
int tty_send_xchar(struct tty_struct *tty, char ch);
int tty_put_char(struct tty_struct *tty, unsigned char c);
unsigned int tty_chars_in_buffer(struct tty_struct *tty);
unsigned int tty_write_room(struct tty_struct *tty);
void tty_driver_flush_buffer(struct tty_struct *tty);
void tty_unthrottle(struct tty_struct *tty);
int tty_throttle_safe(struct tty_struct *tty);
int tty_unthrottle_safe(struct tty_struct *tty);
int tty_do_resize(struct tty_struct *tty, struct winsize *ws);
int tty_get_icount(struct tty_struct *tty,
struct serial_icounter_struct *icount);
int is_current_pgrp_orphaned(void);
void tty_hangup(struct tty_struct *tty);
void tty_vhangup(struct tty_struct *tty);
int tty_hung_up_p(struct file *filp);
void do_SAK(struct tty_struct *tty);
void __do_SAK(struct tty_struct *tty);
void no_tty(void);
speed_t tty_termios_baud_rate(const struct ktermios *termios);
void tty_termios_encode_baud_rate(struct ktermios *termios, speed_t ibaud,
speed_t obaud);
void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud,
speed_t obaud);
/**
* tty_get_baud_rate - get tty bit rates
* @tty: tty to query
*
* Returns the baud rate as an integer for this terminal. The
* termios lock must be held by the caller and the terminal bit
* flags may be updated.
*
* Locking: none
*/
static inline speed_t tty_get_baud_rate(struct tty_struct *tty)
{
return tty_termios_baud_rate(&tty->termios);
}
unsigned char tty_get_char_size(unsigned int cflag);
unsigned char tty_get_frame_size(unsigned int cflag);
void tty_termios_copy_hw(struct ktermios *new, const struct ktermios *old);
bool tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b);
int tty_set_termios(struct tty_struct *tty, struct ktermios *kt);
void tty_wakeup(struct tty_struct *tty);
int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
int tty_perform_flush(struct tty_struct *tty, unsigned long arg);
struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
void tty_release_struct(struct tty_struct *tty, int idx);
void tty_init_termios(struct tty_struct *tty);
void tty_save_termios(struct tty_struct *tty);
int tty_standard_install(struct tty_driver *driver,
struct tty_struct *tty);
extern struct mutex tty_mutex;
/* n_tty.c */
void n_tty_inherit_ops(struct tty_ldisc_ops *ops);
#ifdef CONFIG_TTY
void __init n_tty_init(void);
#else
static inline void n_tty_init(void) { }
#endif
/* tty_audit.c */
#ifdef CONFIG_AUDIT
void tty_audit_exit(void);
void tty_audit_fork(struct signal_struct *sig);
int tty_audit_push(void);
#else
static inline void tty_audit_exit(void)
{
}
static inline void tty_audit_fork(struct signal_struct *sig)
{
}
static inline int tty_audit_push(void)
{
return 0;
}
#endif
/* tty_ioctl.c */
int n_tty_ioctl_helper(struct tty_struct *tty, unsigned int cmd,
unsigned long arg);
/* vt.c */
int vt_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
long vt_compat_ioctl(struct tty_struct *tty, unsigned int cmd,
unsigned long arg);
/* tty_mutex.c */
/* functions for preparation of BKL removal */
void tty_lock(struct tty_struct *tty);
int tty_lock_interruptible(struct tty_struct *tty);
void tty_unlock(struct tty_struct *tty);
void tty_lock_slave(struct tty_struct *tty);
void tty_unlock_slave(struct tty_struct *tty);
void tty_set_lock_subclass(struct tty_struct *tty);
#endif
Reference in a new issue View git blame Copy permalink