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Commit 9d898966 authored by Thadeu Lima de Souza Cascardo's avatar Thadeu Lima de Souza Cascardo Committed by Greg Kroah-Hartman
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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: default avatarThadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent d64bbeb5

drivers/tty/serial/jsm/jsm.h

+0 −7
Original line number Diff line number Diff line
@@ -180,10 +180,8 @@ struct jsm_board 
/* Our Read/Error/Write queue sizes */

#define RQUEUEMASK	0x1FFF		/* 8 K - 1 */

#define EQUEUEMASK	0x1FFF		/* 8 K - 1 */

#define WQUEUEMASK	0x0FFF		/* 4 K - 1 */

#define RQUEUESIZE	(RQUEUEMASK + 1)

#define EQUEUESIZE	RQUEUESIZE

#define WQUEUESIZE	(WQUEUEMASK + 1)





/************************************************************************
@@ -223,10 +221,6 @@ struct jsm_channel { 
	u16		ch_e_head;	/* Head location of the error queue */

	u16		ch_e_tail;	/* Tail location of the error queue */



	u8		*ch_wqueue;	/* Our write queue buffer - malloc'ed */

	u16		ch_w_head;	/* Head location of the write queue */

	u16		ch_w_tail;	/* Tail location of the write queue */



	u64		ch_rxcount;	/* total of data received so far */

	u64		ch_txcount;	/* total of data transmitted so far */
@@ -375,7 +369,6 @@ extern int jsm_debug; 
 * Prototypes for non-static functions used in more than one module

 *

 *************************************************************************/

int jsm_tty_write(struct uart_port *port);

int jsm_tty_init(struct jsm_board *);

int jsm_uart_port_init(struct jsm_board *);

int jsm_remove_uart_port(struct jsm_board *);

drivers/tty/serial/jsm/jsm_driver.c

+0 −1
Original line number Diff line number Diff line
@@ -194,7 +194,6 @@ static void __devexit jsm_remove_one(struct pci_dev *pdev) 
		if (brd->channels[i]) {

			kfree(brd->channels[i]->ch_rqueue);

			kfree(brd->channels[i]->ch_equeue);

			kfree(brd->channels[i]->ch_wqueue);

			kfree(brd->channels[i]);

		}

	}

drivers/tty/serial/jsm/jsm_neo.c

+15 −14
Original line number Diff line number Diff line
@@ -496,12 +496,15 @@ static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch) 
	int s;

	int qlen;

	u32 len_written = 0;

	struct circ_buf *circ;



	if (!ch)

		return;



	circ = &ch->uart_port.state->xmit;



	/* No data to write to the UART */

	if (ch->ch_w_tail == ch->ch_w_head)

	if (uart_circ_empty(circ))

		return;



	/* If port is "stopped", don't send any data to the UART */
@@ -517,11 +520,10 @@ static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch) 
		if (ch->ch_cached_lsr & UART_LSR_THRE) {

			ch->ch_cached_lsr &= ~(UART_LSR_THRE);



			writeb(ch->ch_wqueue[ch->ch_w_tail], &ch->ch_neo_uart->txrx);

			writeb(circ->buf[circ->tail], &ch->ch_neo_uart->txrx);

			jsm_printk(WRITE, INFO, &ch->ch_bd->pci_dev,

					"Tx data: %x\n", ch->ch_wqueue[ch->ch_w_head]);

			ch->ch_w_tail++;

			ch->ch_w_tail &= WQUEUEMASK;

					"Tx data: %x\n", circ->buf[circ->head]);

			circ->tail = (circ->tail + 1) & (UART_XMIT_SIZE - 1);

			ch->ch_txcount++;

		}

		return;
@@ -536,36 +538,36 @@ static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch) 
	n = UART_17158_TX_FIFOSIZE - ch->ch_t_tlevel;



	/* cache head and tail of queue */

	head = ch->ch_w_head & WQUEUEMASK;

	tail = ch->ch_w_tail & WQUEUEMASK;

	qlen = (head - tail) & WQUEUEMASK;

	head = circ->head & (UART_XMIT_SIZE - 1);

	tail = circ->tail & (UART_XMIT_SIZE - 1);

	qlen = uart_circ_chars_pending(circ);



	/* Find minimum of the FIFO space, versus queue length */

	n = min(n, qlen);



	while (n > 0) {



		s = ((head >= tail) ? head : WQUEUESIZE) - tail;

		s = ((head >= tail) ? head : UART_XMIT_SIZE) - tail;

		s = min(s, n);



		if (s <= 0)

			break;



		memcpy_toio(&ch->ch_neo_uart->txrxburst, ch->ch_wqueue + tail, s);

		memcpy_toio(&ch->ch_neo_uart->txrxburst, circ->buf + tail, s);

		/* Add and flip queue if needed */

		tail = (tail + s) & WQUEUEMASK;

		tail = (tail + s) & (UART_XMIT_SIZE - 1);

		n -= s;

		ch->ch_txcount += s;

		len_written += s;

	}



	/* Update the final tail */

	ch->ch_w_tail = tail & WQUEUEMASK;

	circ->tail = tail & (UART_XMIT_SIZE - 1);



	if (len_written >= ch->ch_t_tlevel)

		ch->ch_flags &= ~(CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);



	if (!jsm_tty_write(&ch->uart_port))

	if (uart_circ_empty(circ))

		uart_write_wakeup(&ch->uart_port);

}
@@ -946,7 +948,6 @@ static void neo_param(struct jsm_channel *ch) 
	if ((ch->ch_c_cflag & (CBAUD)) == 0) {

		ch->ch_r_head = ch->ch_r_tail = 0;

		ch->ch_e_head = ch->ch_e_tail = 0;

		ch->ch_w_head = ch->ch_w_tail = 0;



		neo_flush_uart_write(ch);

		neo_flush_uart_read(ch);

drivers/tty/serial/jsm/jsm_tty.c

+13 −81
Original line number Diff line number Diff line
@@ -118,6 +118,19 @@ static void jsm_tty_set_mctrl(struct uart_port *port, unsigned int mctrl) 
	udelay(10);

}



/*

 * jsm_tty_write()

 *

 * Take data from the user or kernel and send it out to the FEP.

 * In here exists all the Transparent Print magic as well.

 */

static void jsm_tty_write(struct uart_port *port)

{

	struct jsm_channel *channel;

	channel = container_of(port, struct jsm_channel, uart_port);

	channel->ch_bd->bd_ops->copy_data_from_queue_to_uart(channel);

}



static void jsm_tty_start_tx(struct uart_port *port)

{

	struct jsm_channel *channel = (struct jsm_channel *)port;
@@ -216,14 +229,6 @@ static int jsm_tty_open(struct uart_port *port) 
			return -ENOMEM;

		}

	}

	if (!channel->ch_wqueue) {

		channel->ch_wqueue = kzalloc(WQUEUESIZE, GFP_KERNEL);

		if (!channel->ch_wqueue) {

			jsm_printk(INIT, ERR, &channel->ch_bd->pci_dev,

				"unable to allocate write queue buf");

			return -ENOMEM;

		}

	}



	channel->ch_flags &= ~(CH_OPENING);

	/*
@@ -237,7 +242,6 @@ static int jsm_tty_open(struct uart_port *port) 
	 */

	channel->ch_r_head = channel->ch_r_tail = 0;

	channel->ch_e_head = channel->ch_e_tail = 0;

	channel->ch_w_head = channel->ch_w_tail = 0;



	brd->bd_ops->flush_uart_write(channel);

	brd->bd_ops->flush_uart_read(channel);
@@ -836,75 +840,3 @@ void jsm_check_queue_flow_control(struct jsm_channel *ch) 
		}

	}

}
 


/*

 * jsm_tty_write()

 *

 * Take data from the user or kernel and send it out to the FEP.

 * In here exists all the Transparent Print magic as well.

 */

int jsm_tty_write(struct uart_port *port)

{

	int bufcount;

	int data_count = 0,data_count1 =0;

	u16 head;

	u16 tail;

	u16 tmask;

	u32 remain;

	int temp_tail = port->state->xmit.tail;

	struct jsm_channel *channel = (struct jsm_channel *)port;



	tmask = WQUEUEMASK;

	head = (channel->ch_w_head) & tmask;

	tail = (channel->ch_w_tail) & tmask;



	if ((bufcount = tail - head - 1) < 0)

		bufcount += WQUEUESIZE;



	bufcount = min(bufcount, 56);

	remain = WQUEUESIZE - head;



	data_count = 0;

	if (bufcount >= remain) {

		bufcount -= remain;

		while ((port->state->xmit.head != temp_tail) &&

		(data_count < remain)) {

			channel->ch_wqueue[head++] =

			port->state->xmit.buf[temp_tail];



			temp_tail++;

			temp_tail &= (UART_XMIT_SIZE - 1);

			data_count++;

		}

		if (data_count == remain) head = 0;

	}



	data_count1 = 0;

	if (bufcount > 0) {

		remain = bufcount;

		while ((port->state->xmit.head != temp_tail) &&

			(data_count1 < remain)) {

			channel->ch_wqueue[head++] =

				port->state->xmit.buf[temp_tail];



			temp_tail++;

			temp_tail &= (UART_XMIT_SIZE - 1);

			data_count1++;



		}

	}



	port->state->xmit.tail = temp_tail;



	data_count += data_count1;

	if (data_count) {

		head &= tmask;

		channel->ch_w_head = head;

	}



	if (data_count) {

		channel->ch_bd->bd_ops->copy_data_from_queue_to_uart(channel);

	}



	return data_count;

}