jsm: remove buggy write queue
jsm uses a write queue that copies from uart_core circular buffer. This copying however has some bugs, like not wrapping the head counter. Since this write queue is also a circular buffer, the consumer function is ready to use the uart_core circular buffer directly. This buggy copying function was making some bytes be dropped when transmitting to a raw tty, doing something like this. [root@hostname ~]$ cat /dev/ttyn1 > cascardo/dump & [1] 2658 [root@hostname ~]$ cat /proc/tty/drivers > /dev/ttyn0 [root@hostname ~]$ cat /proc/tty/drivers /dev/tty /dev/tty 5 0 system:/dev/tty /dev/console /dev/console 5 1 system:console /dev/ptmx /dev/ptmx 5 2 system /dev/vc/0 /dev/vc/0 4 0 system:vtmaster jsm /dev/ttyn 250 0-31 serial serial /dev/ttyS 4 64-95 serial hvc /dev/hvc 229 0-7 system pty_slave /dev/pts 136 0-1048575 pty:slave pty_master /dev/ptm 128 0-1048575 pty:master unknown /dev/tty 4 1-63 console [root@hostname ~]$ cat cascardo/dump /dev/tty /dev/tty 5 0 system:/dev/tty /dev/console /dev/console 5 1 system:console /dev/ptmx /dev/ptmx 5 2 system /dev/vc/0 /dev/vc/0 4 0 system:vtmaste[root@hostname ~]$ This patch drops the driver write queue entirely, using the circular buffer from uart_core only. Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Thadeu Lima de Souza Cascardo
Greg Kroah-Hartman
parent
d64bbeb57f
commit
9d898966c4
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@ -180,10 +180,8 @@ struct jsm_board
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/* Our Read/Error/Write queue sizes */
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#define RQUEUEMASK 0x1FFF /* 8 K - 1 */
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#define EQUEUEMASK 0x1FFF /* 8 K - 1 */
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#define WQUEUEMASK 0x0FFF /* 4 K - 1 */
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#define RQUEUESIZE (RQUEUEMASK + 1)
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#define EQUEUESIZE RQUEUESIZE
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#define WQUEUESIZE (WQUEUEMASK + 1)
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/************************************************************************
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@ -223,10 +221,6 @@ struct jsm_channel {
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u16 ch_e_head; /* Head location of the error queue */
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u16 ch_e_tail; /* Tail location of the error queue */
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u8 *ch_wqueue; /* Our write queue buffer - malloc'ed */
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u16 ch_w_head; /* Head location of the write queue */
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u16 ch_w_tail; /* Tail location of the write queue */
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u64 ch_rxcount; /* total of data received so far */
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u64 ch_txcount; /* total of data transmitted so far */
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@ -375,7 +369,6 @@ extern int jsm_debug;
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* Prototypes for non-static functions used in more than one module
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*
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*************************************************************************/
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int jsm_tty_write(struct uart_port *port);
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int jsm_tty_init(struct jsm_board *);
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int jsm_uart_port_init(struct jsm_board *);
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int jsm_remove_uart_port(struct jsm_board *);
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@ -194,7 +194,6 @@ static void __devexit jsm_remove_one(struct pci_dev *pdev)
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if (brd->channels[i]) {
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kfree(brd->channels[i]->ch_rqueue);
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kfree(brd->channels[i]->ch_equeue);
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kfree(brd->channels[i]->ch_wqueue);
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kfree(brd->channels[i]);
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}
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}
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@ -496,12 +496,15 @@ static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch)
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int s;
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int qlen;
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u32 len_written = 0;
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struct circ_buf *circ;
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if (!ch)
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return;
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circ = &ch->uart_port.state->xmit;
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/* No data to write to the UART */
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if (ch->ch_w_tail == ch->ch_w_head)
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if (uart_circ_empty(circ))
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return;
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/* If port is "stopped", don't send any data to the UART */
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@ -517,11 +520,10 @@ static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch)
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if (ch->ch_cached_lsr & UART_LSR_THRE) {
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ch->ch_cached_lsr &= ~(UART_LSR_THRE);
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writeb(ch->ch_wqueue[ch->ch_w_tail], &ch->ch_neo_uart->txrx);
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writeb(circ->buf[circ->tail], &ch->ch_neo_uart->txrx);
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jsm_printk(WRITE, INFO, &ch->ch_bd->pci_dev,
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"Tx data: %x\n", ch->ch_wqueue[ch->ch_w_head]);
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ch->ch_w_tail++;
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ch->ch_w_tail &= WQUEUEMASK;
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"Tx data: %x\n", circ->buf[circ->head]);
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circ->tail = (circ->tail + 1) & (UART_XMIT_SIZE - 1);
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ch->ch_txcount++;
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}
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return;
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@ -536,36 +538,36 @@ static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch)
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n = UART_17158_TX_FIFOSIZE - ch->ch_t_tlevel;
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/* cache head and tail of queue */
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head = ch->ch_w_head & WQUEUEMASK;
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tail = ch->ch_w_tail & WQUEUEMASK;
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qlen = (head - tail) & WQUEUEMASK;
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head = circ->head & (UART_XMIT_SIZE - 1);
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tail = circ->tail & (UART_XMIT_SIZE - 1);
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qlen = uart_circ_chars_pending(circ);
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/* Find minimum of the FIFO space, versus queue length */
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n = min(n, qlen);
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while (n > 0) {
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s = ((head >= tail) ? head : WQUEUESIZE) - tail;
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s = ((head >= tail) ? head : UART_XMIT_SIZE) - tail;
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s = min(s, n);
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if (s <= 0)
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break;
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memcpy_toio(&ch->ch_neo_uart->txrxburst, ch->ch_wqueue + tail, s);
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memcpy_toio(&ch->ch_neo_uart->txrxburst, circ->buf + tail, s);
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/* Add and flip queue if needed */
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tail = (tail + s) & WQUEUEMASK;
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tail = (tail + s) & (UART_XMIT_SIZE - 1);
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n -= s;
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ch->ch_txcount += s;
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len_written += s;
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}
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/* Update the final tail */
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ch->ch_w_tail = tail & WQUEUEMASK;
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circ->tail = tail & (UART_XMIT_SIZE - 1);
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if (len_written >= ch->ch_t_tlevel)
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ch->ch_flags &= ~(CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
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if (!jsm_tty_write(&ch->uart_port))
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if (uart_circ_empty(circ))
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uart_write_wakeup(&ch->uart_port);
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}
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@ -946,7 +948,6 @@ static void neo_param(struct jsm_channel *ch)
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if ((ch->ch_c_cflag & (CBAUD)) == 0) {
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ch->ch_r_head = ch->ch_r_tail = 0;
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ch->ch_e_head = ch->ch_e_tail = 0;
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ch->ch_w_head = ch->ch_w_tail = 0;
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neo_flush_uart_write(ch);
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neo_flush_uart_read(ch);
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@ -118,6 +118,19 @@ static void jsm_tty_set_mctrl(struct uart_port *port, unsigned int mctrl)
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udelay(10);
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}
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/*
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* jsm_tty_write()
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*
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* Take data from the user or kernel and send it out to the FEP.
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* In here exists all the Transparent Print magic as well.
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*/
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static void jsm_tty_write(struct uart_port *port)
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{
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struct jsm_channel *channel;
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channel = container_of(port, struct jsm_channel, uart_port);
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channel->ch_bd->bd_ops->copy_data_from_queue_to_uart(channel);
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}
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static void jsm_tty_start_tx(struct uart_port *port)
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{
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struct jsm_channel *channel = (struct jsm_channel *)port;
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@ -216,14 +229,6 @@ static int jsm_tty_open(struct uart_port *port)
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return -ENOMEM;
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}
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}
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if (!channel->ch_wqueue) {
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channel->ch_wqueue = kzalloc(WQUEUESIZE, GFP_KERNEL);
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if (!channel->ch_wqueue) {
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jsm_printk(INIT, ERR, &channel->ch_bd->pci_dev,
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"unable to allocate write queue buf");
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return -ENOMEM;
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}
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}
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channel->ch_flags &= ~(CH_OPENING);
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/*
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@ -237,7 +242,6 @@ static int jsm_tty_open(struct uart_port *port)
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*/
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channel->ch_r_head = channel->ch_r_tail = 0;
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channel->ch_e_head = channel->ch_e_tail = 0;
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channel->ch_w_head = channel->ch_w_tail = 0;
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brd->bd_ops->flush_uart_write(channel);
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brd->bd_ops->flush_uart_read(channel);
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@ -836,75 +840,3 @@ void jsm_check_queue_flow_control(struct jsm_channel *ch)
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}
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}
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}
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/*
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* jsm_tty_write()
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*
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* Take data from the user or kernel and send it out to the FEP.
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* In here exists all the Transparent Print magic as well.
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*/
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int jsm_tty_write(struct uart_port *port)
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{
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int bufcount;
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int data_count = 0,data_count1 =0;
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u16 head;
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u16 tail;
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u16 tmask;
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u32 remain;
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int temp_tail = port->state->xmit.tail;
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struct jsm_channel *channel = (struct jsm_channel *)port;
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tmask = WQUEUEMASK;
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head = (channel->ch_w_head) & tmask;
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tail = (channel->ch_w_tail) & tmask;
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if ((bufcount = tail - head - 1) < 0)
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bufcount += WQUEUESIZE;
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bufcount = min(bufcount, 56);
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remain = WQUEUESIZE - head;
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data_count = 0;
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if (bufcount >= remain) {
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bufcount -= remain;
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while ((port->state->xmit.head != temp_tail) &&
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(data_count < remain)) {
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channel->ch_wqueue[head++] =
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port->state->xmit.buf[temp_tail];
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temp_tail++;
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temp_tail &= (UART_XMIT_SIZE - 1);
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data_count++;
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}
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if (data_count == remain) head = 0;
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}
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data_count1 = 0;
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if (bufcount > 0) {
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remain = bufcount;
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while ((port->state->xmit.head != temp_tail) &&
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(data_count1 < remain)) {
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channel->ch_wqueue[head++] =
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port->state->xmit.buf[temp_tail];
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temp_tail++;
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temp_tail &= (UART_XMIT_SIZE - 1);
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data_count1++;
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}
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}
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port->state->xmit.tail = temp_tail;
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data_count += data_count1;
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if (data_count) {
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head &= tmask;
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channel->ch_w_head = head;
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}
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if (data_count) {
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channel->ch_bd->bd_ops->copy_data_from_queue_to_uart(channel);
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}
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return data_count;
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}
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