mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-12 23:33:55 +08:00
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 c545b66c69
(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 <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/20210505091928.22010-13-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
0f3dcf3b5d
commit
6e94dbc7a4
@ -69,9 +69,9 @@ There are debugfs parameters provided for serial communication.
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- 0x01 - tty->warned is on.
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- 0x04 - tty->packed is on.
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- 0x08 - tty->flow_stopped is on.
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- 0x08 - tty->flow.tco_stopped is on.
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- 0x10 - tty->hw_stopped is on.
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- 0x20 - tty->stopped is on.
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- 0x20 - tty->flow.stopped is on.
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* last_tx_msg: Binary blob Prints the last transmitted frame.
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@ -985,7 +985,7 @@ static void tx_done(MGSLPC_INFO *info, struct tty_struct *tty)
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else
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#endif
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{
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if (tty && (tty->stopped || tty->hw_stopped)) {
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if (tty && (tty->flow.stopped || tty->hw_stopped)) {
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tx_stop(info);
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return;
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}
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@ -1005,7 +1005,7 @@ static void tx_ready(MGSLPC_INFO *info, struct tty_struct *tty)
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if (!info->tx_active)
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return;
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} else {
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if (tty && (tty->stopped || tty->hw_stopped)) {
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if (tty && (tty->flow.stopped || tty->hw_stopped)) {
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tx_stop(info);
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return;
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}
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@ -1525,7 +1525,7 @@ static void mgslpc_flush_chars(struct tty_struct *tty)
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if (mgslpc_paranoia_check(info, tty->name, "mgslpc_flush_chars"))
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return;
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if (info->tx_count <= 0 || tty->stopped ||
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if (info->tx_count <= 0 || tty->flow.stopped ||
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tty->hw_stopped || !info->tx_buf)
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return;
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@ -1594,7 +1594,7 @@ static int mgslpc_write(struct tty_struct * tty,
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ret += c;
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}
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start:
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if (info->tx_count && !tty->stopped && !tty->hw_stopped) {
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if (info->tx_count && !tty->flow.stopped && !tty->hw_stopped) {
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spin_lock_irqsave(&info->lock, flags);
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if (!info->tx_active)
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tx_start(info, tty);
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@ -439,7 +439,7 @@ static void sdio_uart_transmit_chars(struct sdio_uart_port *port)
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tty = tty_port_tty_get(&port->port);
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if (tty == NULL || !kfifo_len(xmit) ||
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tty->stopped || tty->hw_stopped) {
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tty->flow.stopped || tty->hw_stopped) {
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sdio_uart_stop_tx(port);
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tty_kref_put(tty);
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return;
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@ -87,8 +87,8 @@ static void ldisc_tx_wakeup(struct tty_struct *tty);
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static inline void update_tty_status(struct ser_device *ser)
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{
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ser->tty_status =
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ser->tty->stopped << 5 |
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ser->tty->flow_stopped << 3 |
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ser->tty->flow.stopped << 5 |
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ser->tty->flow.tco_stopped << 3 |
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ser->tty->packet << 2;
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}
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static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)
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@ -1640,7 +1640,7 @@ tty3270_do_write(struct tty3270 *tp, struct tty_struct *tty,
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int i_msg, i;
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spin_lock_bh(&tp->view.lock);
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for (i_msg = 0; !tty->stopped && i_msg < count; i_msg++) {
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for (i_msg = 0; !tty->flow.stopped && i_msg < count; i_msg++) {
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if (tp->esc_state != 0) {
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/* Continue escape sequence. */
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tty3270_escape_sequence(tp, buf[i_msg]);
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@ -722,7 +722,7 @@ static int fwtty_tx(struct fwtty_port *port, bool drain)
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/* try to write as many dma transactions out as possible */
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n = -EAGAIN;
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while (!tty->stopped && !tty->hw_stopped &&
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while (!tty->flow.stopped && !tty->hw_stopped &&
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!test_bit(STOP_TX, &port->flags)) {
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txn = kmem_cache_alloc(fwtty_txn_cache, GFP_ATOMIC);
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if (!txn) {
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@ -148,7 +148,7 @@ static __inline__ void rtsdtr_ctrl(int bits)
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* ------------------------------------------------------------
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* rs_stop() and rs_start()
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*
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* This routines are called before setting or resetting tty->stopped.
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* This routines are called before setting or resetting tty->flow.stopped.
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* They enable or disable transmitter interrupts, as necessary.
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* ------------------------------------------------------------
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*/
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@ -309,7 +309,7 @@ static void transmit_chars(struct serial_state *info)
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return;
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}
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if (info->xmit.head == info->xmit.tail
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|| info->tport.tty->stopped
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|| info->tport.tty->flow.stopped
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|| info->tport.tty->hw_stopped) {
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info->IER &= ~UART_IER_THRI;
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custom.intena = IF_TBE;
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@ -768,7 +768,7 @@ static void rs_flush_chars(struct tty_struct *tty)
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unsigned long flags;
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if (info->xmit.head == info->xmit.tail
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|| tty->stopped
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|| tty->flow.stopped
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|| tty->hw_stopped
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|| !info->xmit.buf)
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return;
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@ -812,7 +812,7 @@ static int rs_write(struct tty_struct * tty, const unsigned char *buf, int count
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local_irq_restore(flags);
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if (info->xmit.head != info->xmit.tail
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&& !tty->stopped
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&& !tty->flow.stopped
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&& !tty->hw_stopped
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&& !(info->IER & UART_IER_THRI)) {
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info->IER |= UART_IER_THRI;
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@ -1221,7 +1221,7 @@ static int moxa_write_room(struct tty_struct *tty)
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{
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struct moxa_port *ch;
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if (tty->stopped)
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if (tty->flow.stopped)
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return 0;
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ch = tty->driver_data;
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if (ch == NULL)
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@ -1374,7 +1374,7 @@ static int moxa_poll_port(struct moxa_port *p, unsigned int handle,
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clear_bit(EMPTYWAIT, &p->statusflags);
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tty_wakeup(tty);
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}
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if (test_bit(LOWWAIT, &p->statusflags) && !tty->stopped &&
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if (test_bit(LOWWAIT, &p->statusflags) && !tty->flow.stopped &&
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MoxaPortTxQueue(p) <= WAKEUP_CHARS) {
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clear_bit(LOWWAIT, &p->statusflags);
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tty_wakeup(tty);
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@ -1118,7 +1118,7 @@ static int mxser_write(struct tty_struct *tty, const unsigned char *buf, int cou
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total += c;
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}
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if (info->xmit_cnt && !tty->stopped) {
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if (info->xmit_cnt && !tty->flow.stopped) {
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if (!tty->hw_stopped ||
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(info->type == PORT_16550A) ||
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(info->board->chip_flag)) {
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@ -1149,7 +1149,7 @@ static int mxser_put_char(struct tty_struct *tty, unsigned char ch)
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info->xmit_head &= SERIAL_XMIT_SIZE - 1;
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info->xmit_cnt++;
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spin_unlock_irqrestore(&info->slock, flags);
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if (!tty->stopped) {
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if (!tty->flow.stopped) {
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if (!tty->hw_stopped ||
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(info->type == PORT_16550A) ||
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info->board->chip_flag) {
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@ -1169,7 +1169,7 @@ static void mxser_flush_chars(struct tty_struct *tty)
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struct mxser_port *info = tty->driver_data;
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unsigned long flags;
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if (info->xmit_cnt <= 0 || tty->stopped || !info->port.xmit_buf ||
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if (info->xmit_cnt <= 0 || tty->flow.stopped || !info->port.xmit_buf ||
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(tty->hw_stopped && info->type != PORT_16550A &&
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!info->board->chip_flag))
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return;
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@ -1917,7 +1917,7 @@ static void mxser_unthrottle(struct tty_struct *tty)
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/*
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* mxser_stop() and mxser_start()
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*
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* This routines are called before setting or resetting tty->stopped.
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* This routines are called before setting or resetting tty->flow.stopped.
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* They enable or disable transmitter interrupts, as necessary.
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*/
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static void mxser_stop(struct tty_struct *tty)
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@ -1963,7 +1963,7 @@ static void mxser_set_termios(struct tty_struct *tty, struct ktermios *old_termi
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/* Handle sw stopped */
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if ((old_termios->c_iflag & IXON) && !I_IXON(tty)) {
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tty->stopped = 0;
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tty->flow.stopped = 0;
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if (info->board->chip_flag) {
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spin_lock_irqsave(&info->slock, flags);
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@ -2175,7 +2175,7 @@ static void mxser_transmit_chars(struct tty_struct *tty, struct mxser_port *port
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if (port->port.xmit_buf == NULL)
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return;
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if (port->xmit_cnt <= 0 || tty->stopped ||
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if (port->xmit_cnt <= 0 || tty->flow.stopped ||
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(tty->hw_stopped &&
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(port->type != PORT_16550A) &&
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(!port->board->chip_flag))) {
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@ -1289,7 +1289,7 @@ static void n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
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}
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}
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if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
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if (tty->flow.stopped && !tty->flow.tco_stopped && I_IXON(tty) && I_IXANY(tty)) {
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start_tty(tty);
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process_echoes(tty);
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}
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@ -1398,7 +1398,7 @@ static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
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{
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struct n_tty_data *ldata = tty->disc_data;
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if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
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if (tty->flow.stopped && !tty->flow.tco_stopped && I_IXON(tty) && I_IXANY(tty)) {
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start_tty(tty);
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process_echoes(tty);
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}
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@ -1427,7 +1427,7 @@ static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
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if (c == STOP_CHAR(tty))
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stop_tty(tty);
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else if (c == START_CHAR(tty) ||
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(tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
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(tty->flow.stopped && !tty->flow.tco_stopped && I_IXANY(tty) &&
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c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
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c != SUSP_CHAR(tty))) {
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start_tty(tty);
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@ -1797,7 +1797,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
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* Fix tty hang when I_IXON(tty) is cleared, but the tty
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* been stopped by STOP_CHAR(tty) before it.
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*/
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if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
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if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow.tco_stopped) {
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start_tty(tty);
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process_echoes(tty);
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}
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@ -113,7 +113,7 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
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struct tty_struct *to = tty->link;
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unsigned long flags;
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if (tty->stopped)
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if (tty->flow.stopped)
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return 0;
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if (c > 0) {
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@ -138,7 +138,7 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
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static int pty_write_room(struct tty_struct *tty)
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{
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if (tty->stopped)
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if (tty->flow.stopped)
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return 0;
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return tty_buffer_space_avail(tty->link->port);
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}
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@ -149,7 +149,7 @@ static unsigned int arc_serial_tx_empty(struct uart_port *port)
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/*
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* Driver internal routine, used by both tty(serial core) as well as tx-isr
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* -Called under spinlock in either cases
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* -also tty->stopped has already been checked
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* -also tty->flow.stopped has already been checked
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* = by uart_start( ) before calling us
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* = tx_ist checks that too before calling
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*/
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@ -115,7 +115,7 @@ static void dz_out(struct dz_port *dport, unsigned offset, u16 value)
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* rs_stop () and rs_start ()
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*
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* These routines are called before setting or resetting
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* tty->stopped. They enable or disable transmitter interrupts,
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* tty->flow.stopped. They enable or disable transmitter interrupts,
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* as necessary.
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* ------------------------------------------------------------
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*/
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@ -768,7 +768,7 @@ static int write(struct tty_struct *tty,
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if (!info->tx_buf || (count > info->max_frame_size))
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return -EIO;
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if (!count || tty->stopped || tty->hw_stopped)
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if (!count || tty->flow.stopped || tty->hw_stopped)
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return 0;
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spin_lock_irqsave(&info->lock, flags);
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@ -889,7 +889,7 @@ static void flush_chars(struct tty_struct *tty)
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return;
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DBGINFO(("%s flush_chars entry tx_count=%d\n", info->device_name, info->tx_count));
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if (info->tx_count <= 0 || tty->stopped ||
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if (info->tx_count <= 0 || tty->flow.stopped ||
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tty->hw_stopped || !info->tx_buf)
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return;
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@ -2241,7 +2241,7 @@ static void isr_txeom(struct slgt_info *info, unsigned short status)
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else
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#endif
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{
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if (info->port.tty && (info->port.tty->stopped || info->port.tty->hw_stopped)) {
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if (info->port.tty && (info->port.tty->flow.stopped || info->port.tty->hw_stopped)) {
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tx_stop(info);
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return;
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}
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@ -778,14 +778,14 @@ EXPORT_SYMBOL(tty_hung_up_p);
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* but not always.
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*
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* Locking:
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* flow_lock
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* flow.lock
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*/
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void __stop_tty(struct tty_struct *tty)
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{
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if (tty->stopped)
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if (tty->flow.stopped)
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return;
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tty->stopped = 1;
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tty->flow.stopped = true;
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if (tty->ops->stop)
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tty->ops->stop(tty);
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}
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@ -794,9 +794,9 @@ void stop_tty(struct tty_struct *tty)
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{
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unsigned long flags;
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spin_lock_irqsave(&tty->flow_lock, flags);
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spin_lock_irqsave(&tty->flow.lock, flags);
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__stop_tty(tty);
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spin_unlock_irqrestore(&tty->flow_lock, flags);
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spin_unlock_irqrestore(&tty->flow.lock, flags);
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}
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EXPORT_SYMBOL(stop_tty);
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@ -809,14 +809,14 @@ EXPORT_SYMBOL(stop_tty);
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* start method is invoked and the line discipline woken.
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*
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* Locking:
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* flow_lock
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* flow.lock
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*/
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void __start_tty(struct tty_struct *tty)
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{
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if (!tty->stopped || tty->flow_stopped)
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if (!tty->flow.stopped || tty->flow.tco_stopped)
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return;
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tty->stopped = 0;
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tty->flow.stopped = false;
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if (tty->ops->start)
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tty->ops->start(tty);
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tty_wakeup(tty);
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@ -826,9 +826,9 @@ void start_tty(struct tty_struct *tty)
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{
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unsigned long flags;
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spin_lock_irqsave(&tty->flow_lock, flags);
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spin_lock_irqsave(&tty->flow.lock, flags);
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__start_tty(tty);
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spin_unlock_irqrestore(&tty->flow_lock, flags);
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spin_unlock_irqrestore(&tty->flow.lock, flags);
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}
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EXPORT_SYMBOL(start_tty);
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@ -1172,7 +1172,7 @@ ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter)
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int tty_send_xchar(struct tty_struct *tty, char ch)
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{
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int was_stopped = tty->stopped;
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bool was_stopped = tty->flow.stopped;
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if (tty->ops->send_xchar) {
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down_read(&tty->termios_rwsem);
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@ -3141,7 +3141,7 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
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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);
|
||||
|
@ -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)
|
||||
|
@ -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);
|
||||
|
@ -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);
|
||||
|
@ -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 */
|
||||
}
|
||||
|
@ -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;
|
||||
}
|
||||
|
@ -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,
|
||||
|
@ -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:
|
||||
*
|
||||
|
Loading…
Reference in New Issue
Block a user