diff options
| -rw-r--r-- | drivers/tty/serial/serial_core.c | 171 | ||||
| -rw-r--r-- | include/linux/serial_core.h | 2 |
2 files changed, 130 insertions, 43 deletions
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index e605f0328182..1887f9c71f85 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -64,6 +64,35 @@ static int uart_dcd_enabled(struct uart_port *uport) return !!(uport->status & UPSTAT_DCD_ENABLE); } +static inline struct uart_port *uart_port_ref(struct uart_state *state) +{ + if (atomic_add_unless(&state->refcount, 1, 0)) + return state->uart_port; + return NULL; +} + +static inline void uart_port_deref(struct uart_port *uport) +{ + if (uport && atomic_dec_and_test(&uport->state->refcount)) + wake_up(&uport->state->remove_wait); +} + +#define uart_port_lock(state, flags) \ + ({ \ + struct uart_port *__uport = uart_port_ref(state); \ + if (__uport) \ + spin_lock_irqsave(&__uport->lock, flags); \ + __uport; \ + }) + +#define uart_port_unlock(uport, flags) \ + ({ \ + struct uart_port *__uport = uport; \ + if (__uport) \ + spin_unlock_irqrestore(&__uport->lock, flags); \ + uart_port_deref(__uport); \ + }) + static inline struct uart_port *uart_port_check(struct uart_state *state) { #ifdef CONFIG_LOCKDEP @@ -90,12 +119,13 @@ void uart_write_wakeup(struct uart_port *port) static void uart_stop(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; - struct uart_port *port = state->uart_port; + struct uart_port *port; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); - port->ops->stop_tx(port); - spin_unlock_irqrestore(&port->lock, flags); + port = uart_port_lock(state, flags); + if (port) + port->ops->stop_tx(port); + uart_port_unlock(port, flags); } static void __uart_start(struct tty_struct *tty) @@ -103,19 +133,19 @@ static void __uart_start(struct tty_struct *tty) struct uart_state *state = tty->driver_data; struct uart_port *port = state->uart_port; - if (!uart_tx_stopped(port)) + if (port && !uart_tx_stopped(port)) port->ops->start_tx(port); } static void uart_start(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; - struct uart_port *port = state->uart_port; + struct uart_port *port; unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + port = uart_port_lock(state, flags); __uart_start(tty); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock(port, flags); } static void @@ -496,7 +526,7 @@ static void uart_change_speed(struct tty_struct *tty, struct uart_state *state, static int uart_put_char(struct tty_struct *tty, unsigned char c) { struct uart_state *state = tty->driver_data; - struct uart_port *port = state->uart_port; + struct uart_port *port; struct circ_buf *circ; unsigned long flags; int ret = 0; @@ -505,13 +535,13 @@ static int uart_put_char(struct tty_struct *tty, unsigned char c) if (!circ->buf) return 0; - spin_lock_irqsave(&port->lock, flags); - if (uart_circ_chars_free(circ) != 0) { + port = uart_port_lock(state, flags); + if (port && uart_circ_chars_free(circ) != 0) { circ->buf[circ->head] = c; circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1); ret = 1; } - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock(port, flags); return ret; } @@ -538,14 +568,12 @@ static int uart_write(struct tty_struct *tty, return -EL3HLT; } - port = state->uart_port; circ = &state->xmit; - if (!circ->buf) return 0; - spin_lock_irqsave(&port->lock, flags); - while (1) { + port = uart_port_lock(state, flags); + while (port) { c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE); if (count < c) c = count; @@ -559,32 +587,33 @@ static int uart_write(struct tty_struct *tty, } __uart_start(tty); - spin_unlock_irqrestore(&port->lock, flags); - + uart_port_unlock(port, flags); return ret; } static int uart_write_room(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; + struct uart_port *port; unsigned long flags; int ret; - spin_lock_irqsave(&state->uart_port->lock, flags); + port = uart_port_lock(state, flags); ret = uart_circ_chars_free(&state->xmit); - spin_unlock_irqrestore(&state->uart_port->lock, flags); + uart_port_unlock(port, flags); return ret; } static int uart_chars_in_buffer(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; + struct uart_port *port; unsigned long flags; int ret; - spin_lock_irqsave(&state->uart_port->lock, flags); + port = uart_port_lock(state, flags); ret = uart_circ_chars_pending(&state->xmit); - spin_unlock_irqrestore(&state->uart_port->lock, flags); + uart_port_unlock(port, flags); return ret; } @@ -603,14 +632,15 @@ static void uart_flush_buffer(struct tty_struct *tty) return; } - port = state->uart_port; pr_debug("uart_flush_buffer(%d) called\n", tty->index); - spin_lock_irqsave(&port->lock, flags); + port = uart_port_lock(state, flags); + if (!port) + return; uart_circ_clear(&state->xmit); if (port->ops->flush_buffer) port->ops->flush_buffer(port); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock(port, flags); tty_wakeup(tty); } @@ -621,9 +651,13 @@ static void uart_flush_buffer(struct tty_struct *tty) static void uart_send_xchar(struct tty_struct *tty, char ch) { struct uart_state *state = tty->driver_data; - struct uart_port *port = state->uart_port; + struct uart_port *port; unsigned long flags; + port = uart_port_ref(state); + if (!port) + return; + if (port->ops->send_xchar) port->ops->send_xchar(port, ch); else { @@ -633,14 +667,19 @@ static void uart_send_xchar(struct tty_struct *tty, char ch) port->ops->start_tx(port); spin_unlock_irqrestore(&port->lock, flags); } + uart_port_deref(port); } static void uart_throttle(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; - struct uart_port *port = state->uart_port; + struct uart_port *port; upstat_t mask = 0; + port = uart_port_ref(state); + if (!port) + return; + if (I_IXOFF(tty)) mask |= UPSTAT_AUTOXOFF; if (C_CRTSCTS(tty)) @@ -656,14 +695,20 @@ static void uart_throttle(struct tty_struct *tty) if (mask & UPSTAT_AUTOXOFF) uart_send_xchar(tty, STOP_CHAR(tty)); + + uart_port_deref(port); } static void uart_unthrottle(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; - struct uart_port *port = state->uart_port; + struct uart_port *port; upstat_t mask = 0; + port = uart_port_ref(state); + if (!port) + return; + if (I_IXOFF(tty)) mask |= UPSTAT_AUTOXOFF; if (C_CRTSCTS(tty)) @@ -679,6 +724,8 @@ static void uart_unthrottle(struct tty_struct *tty) if (mask & UPSTAT_AUTOXOFF) uart_send_xchar(tty, START_CHAR(tty)); + + uart_port_deref(port); } static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo) @@ -1116,10 +1163,9 @@ static void uart_enable_ms(struct uart_port *uport) * FIXME: This wants extracting into a common all driver implementation * of TIOCMWAIT using tty_port. */ -static int -uart_wait_modem_status(struct uart_state *state, unsigned long arg) +static int uart_wait_modem_status(struct uart_state *state, unsigned long arg) { - struct uart_port *uport = state->uart_port; + struct uart_port *uport; struct tty_port *port = &state->port; DECLARE_WAITQUEUE(wait, current); struct uart_icount cprev, cnow; @@ -1128,6 +1174,9 @@ uart_wait_modem_status(struct uart_state *state, unsigned long arg) /* * note the counters on entry */ + uport = uart_port_ref(state); + if (!uport) + return -EIO; spin_lock_irq(&uport->lock); memcpy(&cprev, &uport->icount, sizeof(struct uart_icount)); uart_enable_ms(uport); @@ -1161,6 +1210,7 @@ uart_wait_modem_status(struct uart_state *state, unsigned long arg) } __set_current_state(TASK_RUNNING); remove_wait_queue(&port->delta_msr_wait, &wait); + uart_port_deref(uport); return ret; } @@ -1176,11 +1226,15 @@ static int uart_get_icount(struct tty_struct *tty, { struct uart_state *state = tty->driver_data; struct uart_icount cnow; - struct uart_port *uport = state->uart_port; + struct uart_port *uport; + uport = uart_port_ref(state); + if (!uport) + return -EIO; spin_lock_irq(&uport->lock); memcpy(&cnow, &uport->icount, sizeof(struct uart_icount)); spin_unlock_irq(&uport->lock); + uart_port_deref(uport); icount->cts = cnow.cts; icount->dsr = cnow.dsr; @@ -1481,11 +1535,14 @@ static void uart_close(struct tty_struct *tty, struct file *filp) static void uart_wait_until_sent(struct tty_struct *tty, int timeout) { struct uart_state *state = tty->driver_data; - struct uart_port *port = state->uart_port; + struct uart_port *port; unsigned long char_time, expire; - if (port->type == PORT_UNKNOWN || port->fifosize == 0) + port = uart_port_ref(state); + if (!port || port->type == PORT_UNKNOWN || port->fifosize == 0) { + uart_port_deref(port); return; + } /* * Set the check interval to be 1/5 of the estimated time to @@ -1531,6 +1588,7 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout) if (time_after(jiffies, expire)) break; } + uart_port_deref(port); } /* @@ -1591,12 +1649,23 @@ static void uart_port_shutdown(struct tty_port *port) static int uart_carrier_raised(struct tty_port *port) { struct uart_state *state = container_of(port, struct uart_state, port); - struct uart_port *uport = state->uart_port; + struct uart_port *uport; int mctrl; + + uport = uart_port_ref(state); + /* + * Should never observe uport == NULL since checks for hangup should + * abort the tty_port_block_til_ready() loop before checking for carrier + * raised -- but report carrier raised if it does anyway so open will + * continue and not sleep + */ + if (WARN_ON(!uport)) + return 1; spin_lock_irq(&uport->lock); uart_enable_ms(uport); mctrl = uport->ops->get_mctrl(uport); spin_unlock_irq(&uport->lock); + uart_port_deref(uport); if (mctrl & TIOCM_CAR) return 1; return 0; @@ -1605,12 +1674,18 @@ static int uart_carrier_raised(struct tty_port *port) static void uart_dtr_rts(struct tty_port *port, int onoff) { struct uart_state *state = container_of(port, struct uart_state, port); - struct uart_port *uport = state->uart_port; + struct uart_port *uport; + + uport = uart_port_ref(state); + if (!uport) + return; if (onoff) uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS); else uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS); + + uart_port_deref(uport); } /* @@ -2320,12 +2395,15 @@ static int uart_poll_get_char(struct tty_driver *driver, int line) struct uart_driver *drv = driver->driver_state; struct uart_state *state = drv->state + line; struct uart_port *port; + int ret = -1; - if (!state || !state->uart_port) - return -1; - - port = state->uart_port; - return port->ops->poll_get_char(port); + if (state) { + port = uart_port_ref(state); + if (port) + ret = port->ops->poll_get_char(port); + uart_port_deref(port); + } + return ret; } static void uart_poll_put_char(struct tty_driver *driver, int line, char ch) @@ -2334,14 +2412,17 @@ static void uart_poll_put_char(struct tty_driver *driver, int line, char ch) struct uart_state *state = drv->state + line; struct uart_port *port; - if (!state || !state->uart_port) + if (!state) return; - port = state->uart_port; + port = uart_port_ref(state); + if (!port) + return; if (ch == '\n') port->ops->poll_put_char(port, '\r'); port->ops->poll_put_char(port, ch); + uart_port_deref(port); } #endif @@ -2688,6 +2769,8 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport) } /* Link the port to the driver state table and vice versa */ + atomic_set(&state->refcount, 1); + init_waitqueue_head(&state->remove_wait); state->uart_port = uport; uport->state = state; @@ -2816,6 +2899,8 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport) uport->type = PORT_UNKNOWN; mutex_lock(&port->mutex); + WARN_ON(atomic_dec_return(&state->refcount) < 0); + wait_event(state->remove_wait, !atomic_read(&state->refcount)); state->uart_port = NULL; mutex_unlock(&port->mutex); out: diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index cbfcf38e220d..fd4ad4dce11a 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -281,6 +281,8 @@ struct uart_state { enum uart_pm_state pm_state; struct circ_buf xmit; + atomic_t refcount; + wait_queue_head_t remove_wait; struct uart_port *uart_port; }; |