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jsm: remove buggy write queue

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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 2011-08-24 13:14:22 -03:00 committed by Greg Kroah-Hartman
parent d64bbeb57f
commit 9d898966c4
4 changed files with 28 additions and 103 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/tty/serial/jsm/jsm.h
View File

@ -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 *);

1
drivers/tty/serial/jsm/jsm_driver.c
View File

@ -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]);
}
}

29
drivers/tty/serial/jsm/jsm_neo.c
View File

@ -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);

94
drivers/tty/serial/jsm/jsm_tty.c
View File

@ -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;
}