From 6e94dbc7a4e49a028b81302d755bba1a518f973b Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Wed, 5 May 2021 11:19:05 +0200 Subject: [PATCH] tty: cumulate and document tty_struct::flow* members Group the flow flags under a single struct called flow. The new struct contains 'stopped' and 'tco_stopped' bools which used to be bits in a bitfield. The struct also contains the lock protecting them to potentially share the same cache line. Note that commit c545b66c6922b (tty: Serialize tcflow() with other tty flow control changes) added a padding to the original bitfield. It was for the bitfield to occupy a whole 64b word to avoid interferring stores on Alpha (cannot we evaporate this arch with weird implications to C code yet?). But it doesn't work as expected as the padding (tty_struct::unused) is aligned to a 8B boundary too and occupies some bytes from the next word. So make it reliable by: 1) setting __aligned of the struct -- that aligns the start, and 2) making 'unsigned long unused[0]' as the last member of the struct -- pads the end. This is also the perfect time to start the documentation of tty_struct where all this lives. So we start by documenting what these bools actually serve for. And why we do all the alignment dances. Only the few up-to-date information from the Theodore's comment made it into this new Kerneldoc comment. Signed-off-by: Jiri Slaby Cc: "David S. Miller" Cc: Jakub Kicinski Cc: Jonathan Corbet Cc: Arnd Bergmann Cc: Ulf Hansson Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Christian Borntraeger Cc: Shawn Guo Cc: Sascha Hauer Cc: Vineet Gupta Cc: "Maciej W. Rozycki" Link: https://lore.kernel.org/r/20210505091928.22010-13-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman --- Documentation/networking/caif/caif.rst | 4 ++-- drivers/char/pcmcia/synclink_cs.c | 8 +++---- drivers/mmc/core/sdio_uart.c | 2 +- drivers/net/caif/caif_serial.c | 4 ++-- drivers/s390/char/tty3270.c | 2 +- drivers/staging/fwserial/fwserial.c | 2 +- drivers/tty/amiserial.c | 8 +++---- drivers/tty/moxa.c | 4 ++-- drivers/tty/mxser.c | 12 +++++------ drivers/tty/n_tty.c | 8 +++---- drivers/tty/pty.c | 4 ++-- drivers/tty/serial/arc_uart.c | 2 +- drivers/tty/serial/dz.c | 2 +- drivers/tty/synclink_gt.c | 6 +++--- drivers/tty/tty_io.c | 24 ++++++++++----------- drivers/tty/tty_ioctl.c | 16 +++++++------- drivers/tty/tty_port.c | 2 +- drivers/tty/vt/keyboard.c | 2 +- drivers/tty/vt/vt.c | 4 ++-- include/linux/serial_core.h | 2 +- include/linux/tty.h | 38 ++++++++++++++++++++-------------- include/linux/tty_driver.h | 4 ++-- 22 files changed, 83 insertions(+), 77 deletions(-) diff --git a/Documentation/networking/caif/caif.rst b/Documentation/networking/caif/caif.rst index 81a1437..d922d41 100644 --- a/Documentation/networking/caif/caif.rst +++ b/Documentation/networking/caif/caif.rst @@ -69,9 +69,9 @@ There are debugfs parameters provided for serial communication. - 0x01 - tty->warned is on. - 0x04 - tty->packed is on. - - 0x08 - tty->flow_stopped is on. + - 0x08 - tty->flow.tco_stopped is on. - 0x10 - tty->hw_stopped is on. - - 0x20 - tty->stopped is on. + - 0x20 - tty->flow.stopped is on. * last_tx_msg: Binary blob Prints the last transmitted frame. diff --git a/drivers/char/pcmcia/synclink_cs.c b/drivers/char/pcmcia/synclink_cs.c index 3287a76..b4707bc 100644 --- a/drivers/char/pcmcia/synclink_cs.c +++ b/drivers/char/pcmcia/synclink_cs.c @@ -985,7 +985,7 @@ static void tx_done(MGSLPC_INFO *info, struct tty_struct *tty) else #endif { - if (tty && (tty->stopped || tty->hw_stopped)) { + if (tty && (tty->flow.stopped || tty->hw_stopped)) { tx_stop(info); return; } @@ -1005,7 +1005,7 @@ static void tx_ready(MGSLPC_INFO *info, struct tty_struct *tty) if (!info->tx_active) return; } else { - if (tty && (tty->stopped || tty->hw_stopped)) { + if (tty && (tty->flow.stopped || tty->hw_stopped)) { tx_stop(info); return; } @@ -1525,7 +1525,7 @@ static void mgslpc_flush_chars(struct tty_struct *tty) if (mgslpc_paranoia_check(info, tty->name, "mgslpc_flush_chars")) return; - if (info->tx_count <= 0 || tty->stopped || + if (info->tx_count <= 0 || tty->flow.stopped || tty->hw_stopped || !info->tx_buf) return; @@ -1594,7 +1594,7 @@ static int mgslpc_write(struct tty_struct * tty, ret += c; } start: - if (info->tx_count && !tty->stopped && !tty->hw_stopped) { + if (info->tx_count && !tty->flow.stopped && !tty->hw_stopped) { spin_lock_irqsave(&info->lock, flags); if (!info->tx_active) tx_start(info, tty); diff --git a/drivers/mmc/core/sdio_uart.c b/drivers/mmc/core/sdio_uart.c index be40672..dbcac2b 100644 --- a/drivers/mmc/core/sdio_uart.c +++ b/drivers/mmc/core/sdio_uart.c @@ -439,7 +439,7 @@ static void sdio_uart_transmit_chars(struct sdio_uart_port *port) tty = tty_port_tty_get(&port->port); if (tty == NULL || !kfifo_len(xmit) || - tty->stopped || tty->hw_stopped) { + tty->flow.stopped || tty->hw_stopped) { sdio_uart_stop_tx(port); tty_kref_put(tty); return; diff --git a/drivers/net/caif/caif_serial.c b/drivers/net/caif/caif_serial.c index fb3ca4e..3996cf7 100644 --- a/drivers/net/caif/caif_serial.c +++ b/drivers/net/caif/caif_serial.c @@ -87,8 +87,8 @@ static void ldisc_tx_wakeup(struct tty_struct *tty); static inline void update_tty_status(struct ser_device *ser) { ser->tty_status = - ser->tty->stopped << 5 | - ser->tty->flow_stopped << 3 | + ser->tty->flow.stopped << 5 | + ser->tty->flow.tco_stopped << 3 | ser->tty->packet << 2; } static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty) diff --git a/drivers/s390/char/tty3270.c b/drivers/s390/char/tty3270.c index 307a80f..1b68564 100644 --- a/drivers/s390/char/tty3270.c +++ b/drivers/s390/char/tty3270.c @@ -1640,7 +1640,7 @@ tty3270_do_write(struct tty3270 *tp, struct tty_struct *tty, int i_msg, i; spin_lock_bh(&tp->view.lock); - for (i_msg = 0; !tty->stopped && i_msg < count; i_msg++) { + for (i_msg = 0; !tty->flow.stopped && i_msg < count; i_msg++) { if (tp->esc_state != 0) { /* Continue escape sequence. */ tty3270_escape_sequence(tp, buf[i_msg]); diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c index 1ee6382..4245532 100644 --- a/drivers/staging/fwserial/fwserial.c +++ b/drivers/staging/fwserial/fwserial.c @@ -722,7 +722,7 @@ static int fwtty_tx(struct fwtty_port *port, bool drain) /* try to write as many dma transactions out as possible */ n = -EAGAIN; - while (!tty->stopped && !tty->hw_stopped && + while (!tty->flow.stopped && !tty->hw_stopped && !test_bit(STOP_TX, &port->flags)) { txn = kmem_cache_alloc(fwtty_txn_cache, GFP_ATOMIC); if (!txn) { diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c index ca48ce5..a4b8876 100644 --- a/drivers/tty/amiserial.c +++ b/drivers/tty/amiserial.c @@ -148,7 +148,7 @@ static __inline__ void rtsdtr_ctrl(int bits) * ------------------------------------------------------------ * rs_stop() and rs_start() * - * This routines are called before setting or resetting tty->stopped. + * This routines are called before setting or resetting tty->flow.stopped. * They enable or disable transmitter interrupts, as necessary. * ------------------------------------------------------------ */ @@ -309,7 +309,7 @@ static void transmit_chars(struct serial_state *info) return; } if (info->xmit.head == info->xmit.tail - || info->tport.tty->stopped + || info->tport.tty->flow.stopped || info->tport.tty->hw_stopped) { info->IER &= ~UART_IER_THRI; custom.intena = IF_TBE; @@ -768,7 +768,7 @@ static void rs_flush_chars(struct tty_struct *tty) unsigned long flags; if (info->xmit.head == info->xmit.tail - || tty->stopped + || tty->flow.stopped || tty->hw_stopped || !info->xmit.buf) return; @@ -812,7 +812,7 @@ static int rs_write(struct tty_struct * tty, const unsigned char *buf, int count local_irq_restore(flags); if (info->xmit.head != info->xmit.tail - && !tty->stopped + && !tty->flow.stopped && !tty->hw_stopped && !(info->IER & UART_IER_THRI)) { info->IER |= UART_IER_THRI; diff --git a/drivers/tty/moxa.c b/drivers/tty/moxa.c index 4d4f15b..847ad3d 100644 --- a/drivers/tty/moxa.c +++ b/drivers/tty/moxa.c @@ -1221,7 +1221,7 @@ static int moxa_write_room(struct tty_struct *tty) { struct moxa_port *ch; - if (tty->stopped) + if (tty->flow.stopped) return 0; ch = tty->driver_data; if (ch == NULL) @@ -1374,7 +1374,7 @@ static int moxa_poll_port(struct moxa_port *p, unsigned int handle, clear_bit(EMPTYWAIT, &p->statusflags); tty_wakeup(tty); } - if (test_bit(LOWWAIT, &p->statusflags) && !tty->stopped && + if (test_bit(LOWWAIT, &p->statusflags) && !tty->flow.stopped && MoxaPortTxQueue(p) <= WAKEUP_CHARS) { clear_bit(LOWWAIT, &p->statusflags); tty_wakeup(tty); diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c index 16a852e..85271e1 100644 --- a/drivers/tty/mxser.c +++ b/drivers/tty/mxser.c @@ -1118,7 +1118,7 @@ static int mxser_write(struct tty_struct *tty, const unsigned char *buf, int cou total += c; } - if (info->xmit_cnt && !tty->stopped) { + if (info->xmit_cnt && !tty->flow.stopped) { if (!tty->hw_stopped || (info->type == PORT_16550A) || (info->board->chip_flag)) { @@ -1149,7 +1149,7 @@ static int mxser_put_char(struct tty_struct *tty, unsigned char ch) info->xmit_head &= SERIAL_XMIT_SIZE - 1; info->xmit_cnt++; spin_unlock_irqrestore(&info->slock, flags); - if (!tty->stopped) { + if (!tty->flow.stopped) { if (!tty->hw_stopped || (info->type == PORT_16550A) || info->board->chip_flag) { @@ -1169,7 +1169,7 @@ static void mxser_flush_chars(struct tty_struct *tty) struct mxser_port *info = tty->driver_data; unsigned long flags; - if (info->xmit_cnt <= 0 || tty->stopped || !info->port.xmit_buf || + if (info->xmit_cnt <= 0 || tty->flow.stopped || !info->port.xmit_buf || (tty->hw_stopped && info->type != PORT_16550A && !info->board->chip_flag)) return; @@ -1917,7 +1917,7 @@ static void mxser_unthrottle(struct tty_struct *tty) /* * mxser_stop() and mxser_start() * - * This routines are called before setting or resetting tty->stopped. + * This routines are called before setting or resetting tty->flow.stopped. * They enable or disable transmitter interrupts, as necessary. */ static void mxser_stop(struct tty_struct *tty) @@ -1963,7 +1963,7 @@ static void mxser_set_termios(struct tty_struct *tty, struct ktermios *old_termi /* Handle sw stopped */ if ((old_termios->c_iflag & IXON) && !I_IXON(tty)) { - tty->stopped = 0; + tty->flow.stopped = 0; if (info->board->chip_flag) { spin_lock_irqsave(&info->slock, flags); @@ -2175,7 +2175,7 @@ static void mxser_transmit_chars(struct tty_struct *tty, struct mxser_port *port if (port->port.xmit_buf == NULL) return; - if (port->xmit_cnt <= 0 || tty->stopped || + if (port->xmit_cnt <= 0 || tty->flow.stopped || (tty->hw_stopped && (port->type != PORT_16550A) && (!port->board->chip_flag))) { diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index c32318da..3566bb5 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -1289,7 +1289,7 @@ static void n_tty_receive_char_special(struct tty_struct *tty, unsigned char c) } } - if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) { + if (tty->flow.stopped && !tty->flow.tco_stopped && I_IXON(tty) && I_IXANY(tty)) { start_tty(tty); process_echoes(tty); } @@ -1398,7 +1398,7 @@ static void n_tty_receive_char(struct tty_struct *tty, unsigned char c) { struct n_tty_data *ldata = tty->disc_data; - if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) { + if (tty->flow.stopped && !tty->flow.tco_stopped && I_IXON(tty) && I_IXANY(tty)) { start_tty(tty); process_echoes(tty); } @@ -1427,7 +1427,7 @@ static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c) if (c == STOP_CHAR(tty)) stop_tty(tty); else if (c == START_CHAR(tty) || - (tty->stopped && !tty->flow_stopped && I_IXANY(tty) && + (tty->flow.stopped && !tty->flow.tco_stopped && I_IXANY(tty) && c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty))) { start_tty(tty); @@ -1797,7 +1797,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) * Fix tty hang when I_IXON(tty) is cleared, but the tty * been stopped by STOP_CHAR(tty) before it. */ - if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) { + if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow.tco_stopped) { start_tty(tty); process_echoes(tty); } diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index 9b5d4ae..017f281 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -113,7 +113,7 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c) struct tty_struct *to = tty->link; unsigned long flags; - if (tty->stopped) + if (tty->flow.stopped) return 0; if (c > 0) { @@ -138,7 +138,7 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c) static int pty_write_room(struct tty_struct *tty) { - if (tty->stopped) + if (tty->flow.stopped) return 0; return tty_buffer_space_avail(tty->link->port); } diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c index 1a9444b..596217d 100644 --- a/drivers/tty/serial/arc_uart.c +++ b/drivers/tty/serial/arc_uart.c @@ -149,7 +149,7 @@ static unsigned int arc_serial_tx_empty(struct uart_port *port) /* * Driver internal routine, used by both tty(serial core) as well as tx-isr * -Called under spinlock in either cases - * -also tty->stopped has already been checked + * -also tty->flow.stopped has already been checked * = by uart_start( ) before calling us * = tx_ist checks that too before calling */ diff --git a/drivers/tty/serial/dz.c b/drivers/tty/serial/dz.c index 4552742..6d91e9b 100644 --- a/drivers/tty/serial/dz.c +++ b/drivers/tty/serial/dz.c @@ -115,7 +115,7 @@ static void dz_out(struct dz_port *dport, unsigned offset, u16 value) * rs_stop () and rs_start () * * These routines are called before setting or resetting - * tty->stopped. They enable or disable transmitter interrupts, + * tty->flow.stopped. They enable or disable transmitter interrupts, * as necessary. * ------------------------------------------------------------ */ diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c index 5523cf7..1555dcc 100644 --- a/drivers/tty/synclink_gt.c +++ b/drivers/tty/synclink_gt.c @@ -768,7 +768,7 @@ static int write(struct tty_struct *tty, if (!info->tx_buf || (count > info->max_frame_size)) return -EIO; - if (!count || tty->stopped || tty->hw_stopped) + if (!count || tty->flow.stopped || tty->hw_stopped) return 0; spin_lock_irqsave(&info->lock, flags); @@ -889,7 +889,7 @@ static void flush_chars(struct tty_struct *tty) return; DBGINFO(("%s flush_chars entry tx_count=%d\n", info->device_name, info->tx_count)); - if (info->tx_count <= 0 || tty->stopped || + if (info->tx_count <= 0 || tty->flow.stopped || tty->hw_stopped || !info->tx_buf) return; @@ -2241,7 +2241,7 @@ static void isr_txeom(struct slgt_info *info, unsigned short status) else #endif { - if (info->port.tty && (info->port.tty->stopped || info->port.tty->hw_stopped)) { + if (info->port.tty && (info->port.tty->flow.stopped || info->port.tty->hw_stopped)) { tx_stop(info); return; } diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 5b5e996..9734be2 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -778,14 +778,14 @@ EXPORT_SYMBOL(tty_hung_up_p); * but not always. * * Locking: - * flow_lock + * flow.lock */ void __stop_tty(struct tty_struct *tty) { - if (tty->stopped) + if (tty->flow.stopped) return; - tty->stopped = 1; + tty->flow.stopped = true; if (tty->ops->stop) tty->ops->stop(tty); } @@ -794,9 +794,9 @@ void stop_tty(struct tty_struct *tty) { unsigned long flags; - spin_lock_irqsave(&tty->flow_lock, flags); + spin_lock_irqsave(&tty->flow.lock, flags); __stop_tty(tty); - spin_unlock_irqrestore(&tty->flow_lock, flags); + spin_unlock_irqrestore(&tty->flow.lock, flags); } EXPORT_SYMBOL(stop_tty); @@ -809,14 +809,14 @@ EXPORT_SYMBOL(stop_tty); * start method is invoked and the line discipline woken. * * Locking: - * flow_lock + * flow.lock */ void __start_tty(struct tty_struct *tty) { - if (!tty->stopped || tty->flow_stopped) + if (!tty->flow.stopped || tty->flow.tco_stopped) return; - tty->stopped = 0; + tty->flow.stopped = false; if (tty->ops->start) tty->ops->start(tty); tty_wakeup(tty); @@ -826,9 +826,9 @@ void start_tty(struct tty_struct *tty) { unsigned long flags; - spin_lock_irqsave(&tty->flow_lock, flags); + spin_lock_irqsave(&tty->flow.lock, flags); __start_tty(tty); - spin_unlock_irqrestore(&tty->flow_lock, flags); + spin_unlock_irqrestore(&tty->flow.lock, flags); } EXPORT_SYMBOL(start_tty); @@ -1172,7 +1172,7 @@ ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter) int tty_send_xchar(struct tty_struct *tty, char ch) { - int was_stopped = tty->stopped; + bool was_stopped = tty->flow.stopped; if (tty->ops->send_xchar) { down_read(&tty->termios_rwsem); @@ -3141,7 +3141,7 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx) INIT_WORK(&tty->hangup_work, do_tty_hangup); mutex_init(&tty->atomic_write_lock); spin_lock_init(&tty->ctrl_lock); - spin_lock_init(&tty->flow_lock); + spin_lock_init(&tty->flow.lock); spin_lock_init(&tty->files_lock); INIT_LIST_HEAD(&tty->tty_files); INIT_WORK(&tty->SAK_work, do_SAK_work); diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c index 41f7449..07c88cc 100644 --- a/drivers/tty/tty_ioctl.c +++ b/drivers/tty/tty_ioctl.c @@ -846,20 +846,20 @@ int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file, return retval; switch (arg) { case TCOOFF: - spin_lock_irq(&tty->flow_lock); - if (!tty->flow_stopped) { - tty->flow_stopped = 1; + spin_lock_irq(&tty->flow.lock); + if (!tty->flow.tco_stopped) { + tty->flow.tco_stopped = true; __stop_tty(tty); } - spin_unlock_irq(&tty->flow_lock); + spin_unlock_irq(&tty->flow.lock); break; case TCOON: - spin_lock_irq(&tty->flow_lock); - if (tty->flow_stopped) { - tty->flow_stopped = 0; + spin_lock_irq(&tty->flow.lock); + if (tty->flow.tco_stopped) { + tty->flow.tco_stopped = false; __start_tty(tty); } - spin_unlock_irq(&tty->flow_lock); + spin_unlock_irq(&tty->flow.lock); break; case TCIOFF: if (STOP_CHAR(tty) != __DISABLED_CHAR) diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c index 303c198..0eb5232 100644 --- a/drivers/tty/tty_port.c +++ b/drivers/tty/tty_port.c @@ -587,7 +587,7 @@ int tty_port_close_start(struct tty_port *port, if (tty_port_initialized(port)) { /* Don't block on a stalled port, just pull the chain */ - if (tty->flow_stopped) + if (tty->flow.tco_stopped) tty_driver_flush_buffer(tty); if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE) tty_wait_until_sent(tty, port->closing_wait); diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c index 5d23097..4b0d690 100644 --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -515,7 +515,7 @@ static void fn_hold(struct vc_data *vc) * these routines are also activated by ^S/^Q. * (And SCROLLOCK can also be set by the ioctl KDSKBLED.) */ - if (tty->stopped) + if (tty->flow.stopped) start_tty(tty); else stop_tty(tty); diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index e5040bd..38c677f 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -2888,7 +2888,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co param.vc = vc; - while (!tty->stopped && count) { + while (!tty->flow.stopped && count) { int orig = *buf; buf++; n++; @@ -3265,7 +3265,7 @@ static int con_put_char(struct tty_struct *tty, unsigned char ch) static int con_write_room(struct tty_struct *tty) { - if (tty->stopped) + if (tty->flow.stopped) return 0; return 32768; /* No limit, really; we're not buffering */ } diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index d7ed00f..7445c8f 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -428,7 +428,7 @@ int uart_resume_port(struct uart_driver *reg, struct uart_port *port); static inline int uart_tx_stopped(struct uart_port *port) { struct tty_struct *tty = port->state->port.tty; - if ((tty && tty->stopped) || port->hw_stopped) + if ((tty && tty->flow.stopped) || port->hw_stopped) return 1; return 0; } diff --git a/include/linux/tty.h b/include/linux/tty.h index 5aad222..df3a69b 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -243,20 +243,22 @@ struct tty_port { #define TTY_PORT_KOPENED 5 /* device exclusively opened by kernel */ -/* - * Where all of the state associated with a tty is kept while the tty - * is open. Since the termios state should be kept even if the tty - * has been closed --- for things like the baud rate, etc --- it is - * not stored here, but rather a pointer to the real state is stored - * here. Possible the winsize structure should have the same - * treatment, but (1) the default 80x24 is usually right and (2) it's - * most often used by a windowing system, which will set the correct - * size each time the window is created or resized anyway. - * - TYT, 9/14/92 - */ - struct tty_operations; +/** + * struct tty_struct - state associated with a tty while open + * + * @flow.lock: lock for flow members + * @flow.stopped: tty stopped/started by tty_stop/tty_start + * @flow.tco_stopped: tty stopped/started by TCOOFF/TCOON ioctls (it has + * precedense 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. + * + * All of the state associated with a tty while the tty is open. Persistent + * storage for tty devices is referenced here as @port in struct tty_port. + */ struct tty_struct { int magic; struct kref kref; @@ -275,7 +277,6 @@ struct tty_struct { struct rw_semaphore termios_rwsem; struct mutex winsize_mutex; spinlock_t ctrl_lock; - spinlock_t flow_lock; /* Termios values are protected by the termios rwsem */ struct ktermios termios, termios_locked; char name[64]; @@ -288,9 +289,14 @@ struct tty_struct { unsigned long flags; int count; struct winsize winsize; /* winsize_mutex */ - unsigned long stopped:1, /* flow_lock */ - flow_stopped:1, - unused:BITS_PER_LONG - 2; + + struct { + spinlock_t lock; + bool stopped; + bool tco_stopped; + unsigned long unused[0]; + } __aligned(sizeof(unsigned long)) flow; + int hw_stopped; unsigned long ctrl_status:8, /* ctrl_lock */ packet:1, diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h index 2f719b4..653fa5a 100644 --- a/include/linux/tty_driver.h +++ b/include/linux/tty_driver.h @@ -153,7 +153,7 @@ * This routine notifies the tty driver that it should stop * outputting characters to the tty device. * - * Called with ->flow_lock held. Serialized with start() method. + * Called with ->flow.lock held. Serialized with start() method. * * Optional: * @@ -164,7 +164,7 @@ * This routine notifies the tty driver that it resume sending * characters to the tty device. * - * Called with ->flow_lock held. Serialized with stop() method. + * Called with ->flow.lock held. Serialized with stop() method. * * Optional: * -- 2.7.4