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Subject[PATCH 39/76] tty: kref usage for isicom and moxa
Date
Rather than blindly keep taking krefs we reorder the code in a few places
to pass the tty down to the right place (which is important as from the user
side it is not the case that tty == port->tty in all situations). For the irq
and related paths use the krefs to stop the tty being freed under us.

Signed-off-by: Alan Cox <alan@redhat.com>
---
drivers/char/isicom.c | 61 +++++++++++++++++++++++++------------------------
drivers/char/moxa.c | 61 +++++++++++++++++++++++++++++++------------------
2 files changed, 69 insertions(+), 53 deletions(-)
diff --git a/drivers/char/isicom.c b/drivers/char/isicom.c
index 8f7cc19..7d30ee1 100644
--- a/drivers/char/isicom.c
+++ b/drivers/char/isicom.c
@@ -421,17 +421,16 @@ static void isicom_tx(unsigned long _data)
if (retries >= 100)
goto unlock;

+ tty = tty_port_tty_get(&port->port);
+ if (tty == NULL)
+ goto put_unlock;
+
for (; count > 0; count--, port++) {
/* port not active or tx disabled to force flow control */
if (!(port->port.flags & ASYNC_INITIALIZED) ||
!(port->status & ISI_TXOK))
continue;

- tty = port->port.tty;
-
- if (tty == NULL)
- continue;
-
txcount = min_t(short, TX_SIZE, port->xmit_cnt);
if (txcount <= 0 || tty->stopped || tty->hw_stopped)
continue;
@@ -489,6 +488,8 @@ static void isicom_tx(unsigned long _data)
tty_wakeup(tty);
}

+put_unlock:
+ tty_kref_put(tty);
unlock:
spin_unlock_irqrestore(&isi_card[card].card_lock, flags);
/* schedule another tx for hopefully in about 10ms */
@@ -547,7 +548,7 @@ static irqreturn_t isicom_interrupt(int irq, void *dev_id)
return IRQ_HANDLED;
}

- tty = port->port.tty;
+ tty = tty_port_tty_get(&port->port);
if (tty == NULL) {
word_count = byte_count >> 1;
while (byte_count > 1) {
@@ -588,7 +589,7 @@ static irqreturn_t isicom_interrupt(int irq, void *dev_id)
}

if (port->port.flags & ASYNC_CTS_FLOW) {
- if (port->port.tty->hw_stopped) {
+ if (tty->hw_stopped) {
if (header & ISI_CTS) {
port->port.tty->hw_stopped = 0;
/* start tx ing */
@@ -597,7 +598,7 @@ static irqreturn_t isicom_interrupt(int irq, void *dev_id)
tty_wakeup(tty);
}
} else if (!(header & ISI_CTS)) {
- port->port.tty->hw_stopped = 1;
+ tty->hw_stopped = 1;
/* stop tx ing */
port->status &= ~(ISI_TXOK | ISI_CTS);
}
@@ -660,24 +661,21 @@ static irqreturn_t isicom_interrupt(int irq, void *dev_id)
}
outw(0x0000, base+0x04); /* enable interrupts */
spin_unlock(&card->card_lock);
+ tty_kref_put(tty);

return IRQ_HANDLED;
}

-static void isicom_config_port(struct isi_port *port)
+static void isicom_config_port(struct tty_struct *tty)
{
+ struct isi_port *port = tty->driver_data;
struct isi_board *card = port->card;
- struct tty_struct *tty;
unsigned long baud;
unsigned long base = card->base;
u16 channel_setup, channel = port->channel,
shift_count = card->shift_count;
unsigned char flow_ctrl;

- tty = port->port.tty;
-
- if (tty == NULL)
- return;
/* FIXME: Switch to new tty baud API */
baud = C_BAUD(tty);
if (baud & CBAUDEX) {
@@ -690,7 +688,7 @@ static void isicom_config_port(struct isi_port *port)

/* 1,2,3,4 => 57.6, 115.2, 230, 460 kbps resp. */
if (baud < 1 || baud > 4)
- port->port.tty->termios->c_cflag &= ~CBAUDEX;
+ tty->termios->c_cflag &= ~CBAUDEX;
else
baud += 15;
}
@@ -797,8 +795,9 @@ static inline void isicom_setup_board(struct isi_board *bp)
spin_unlock_irqrestore(&bp->card_lock, flags);
}

-static int isicom_setup_port(struct isi_port *port)
+static int isicom_setup_port(struct tty_struct *tty)
{
+ struct isi_port *port = tty->driver_data;
struct isi_board *card = port->card;
unsigned long flags;

@@ -808,8 +807,7 @@ static int isicom_setup_port(struct isi_port *port)
return -ENOMEM;

spin_lock_irqsave(&card->card_lock, flags);
- if (port->port.tty)
- clear_bit(TTY_IO_ERROR, &port->port.tty->flags);
+ clear_bit(TTY_IO_ERROR, &tty->flags);
if (port->port.count == 1)
card->count++;

@@ -823,7 +821,7 @@ static int isicom_setup_port(struct isi_port *port)
InterruptTheCard(card->base);
}

- isicom_config_port(port);
+ isicom_config_port(tty);
port->port.flags |= ASYNC_INITIALIZED;
spin_unlock_irqrestore(&card->card_lock, flags);

@@ -934,8 +932,8 @@ static int isicom_open(struct tty_struct *tty, struct file *filp)

port->port.count++;
tty->driver_data = port;
- port->port.tty = tty;
- error = isicom_setup_port(port);
+ tty_port_tty_set(&port->port, tty);
+ error = isicom_setup_port(tty);
if (error == 0)
error = block_til_ready(tty, filp, port);
return error;
@@ -955,15 +953,17 @@ static void isicom_shutdown_port(struct isi_port *port)
struct isi_board *card = port->card;
struct tty_struct *tty;

- tty = port->port.tty;
+ tty = tty_port_tty_get(&port->port);

- if (!(port->port.flags & ASYNC_INITIALIZED))
+ if (!(port->port.flags & ASYNC_INITIALIZED)) {
+ tty_kref_put(tty);
return;
+ }

tty_port_free_xmit_buf(&port->port);
port->port.flags &= ~ASYNC_INITIALIZED;
/* 3rd October 2000 : Vinayak P Risbud */
- port->port.tty = NULL;
+ tty_port_tty_set(&port->port, NULL);

/*Fix done by Anil .S on 30-04-2001
remote login through isi port has dtr toggle problem
@@ -1243,9 +1243,10 @@ static int isicom_tiocmset(struct tty_struct *tty, struct file *file,
return 0;
}

-static int isicom_set_serial_info(struct isi_port *port,
- struct serial_struct __user *info)
+static int isicom_set_serial_info(struct tty_struct *tty,
+ struct serial_struct __user *info)
{
+ struct isi_port *port = tty->driver_data;
struct serial_struct newinfo;
int reconfig_port;

@@ -1276,7 +1277,7 @@ static int isicom_set_serial_info(struct isi_port *port,
if (reconfig_port) {
unsigned long flags;
spin_lock_irqsave(&port->card->card_lock, flags);
- isicom_config_port(port);
+ isicom_config_port(tty);
spin_unlock_irqrestore(&port->card->card_lock, flags);
}
unlock_kernel();
@@ -1318,7 +1319,7 @@ static int isicom_ioctl(struct tty_struct *tty, struct file *filp,
return isicom_get_serial_info(port, argp);

case TIOCSSERIAL:
- return isicom_set_serial_info(port, argp);
+ return isicom_set_serial_info(tty, argp);

default:
return -ENOIOCTLCMD;
@@ -1341,7 +1342,7 @@ static void isicom_set_termios(struct tty_struct *tty,
return;

spin_lock_irqsave(&port->card->card_lock, flags);
- isicom_config_port(port);
+ isicom_config_port(tty);
spin_unlock_irqrestore(&port->card->card_lock, flags);

if ((old_termios->c_cflag & CRTSCTS) &&
@@ -1419,7 +1420,7 @@ static void isicom_hangup(struct tty_struct *tty)

port->port.count = 0;
port->port.flags &= ~ASYNC_NORMAL_ACTIVE;
- port->port.tty = NULL;
+ tty_port_tty_set(&port->port, NULL);
wake_up_interruptible(&port->port.open_wait);
}

diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index d3d7864..5df4003 100644
--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -205,7 +205,7 @@ static int moxa_tiocmset(struct tty_struct *tty, struct file *file,
static void moxa_poll(unsigned long);
static void moxa_set_tty_param(struct tty_struct *, struct ktermios *);
static void moxa_setup_empty_event(struct tty_struct *);
-static void moxa_shut_down(struct moxa_port *);
+static void moxa_shut_down(struct tty_struct *);
/*
* moxa board interface functions:
*/
@@ -217,7 +217,7 @@ static void MoxaPortLineCtrl(struct moxa_port *, int, int);
static void MoxaPortFlowCtrl(struct moxa_port *, int, int, int, int, int);
static int MoxaPortLineStatus(struct moxa_port *);
static void MoxaPortFlushData(struct moxa_port *, int);
-static int MoxaPortWriteData(struct moxa_port *, const unsigned char *, int);
+static int MoxaPortWriteData(struct tty_struct *, const unsigned char *, int);
static int MoxaPortReadData(struct moxa_port *);
static int MoxaPortTxQueue(struct moxa_port *);
static int MoxaPortRxQueue(struct moxa_port *);
@@ -332,6 +332,7 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
for (i = 0; i < MAX_BOARDS; i++) {
p = moxa_boards[i].ports;
for (j = 0; j < MAX_PORTS_PER_BOARD; j++, p++, argm++) {
+ struct tty_struct *ttyp;
memset(&tmp, 0, sizeof(tmp));
if (!moxa_boards[i].ready)
goto copy;
@@ -344,10 +345,12 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
if (status & 4)
tmp.dcd = 1;

- if (!p->port.tty || !p->port.tty->termios)
+ ttyp = tty_port_tty_get(&p->port);
+ if (!ttyp || !ttyp->termios)
tmp.cflag = p->cflag;
else
- tmp.cflag = p->port.tty->termios->c_cflag;
+ tmp.cflag = ttyp->termios->c_cflag;
+ tty_kref_put(tty);
copy:
if (copy_to_user(argm, &tmp, sizeof(tmp))) {
mutex_unlock(&moxa_openlock);
@@ -880,8 +883,14 @@ static void moxa_board_deinit(struct moxa_board_conf *brd)

/* pci hot-un-plug support */
for (a = 0; a < brd->numPorts; a++)
- if (brd->ports[a].port.flags & ASYNC_INITIALIZED)
- tty_hangup(brd->ports[a].port.tty);
+ if (brd->ports[a].port.flags & ASYNC_INITIALIZED) {
+ struct tty_struct *tty = tty_port_tty_get(
+ &brd->ports[a].port);
+ if (tty) {
+ tty_hangup(tty);
+ tty_kref_put(tty);
+ }
+ }
while (1) {
opened = 0;
for (a = 0; a < brd->numPorts; a++)
@@ -1096,13 +1105,14 @@ static void __exit moxa_exit(void)
module_init(moxa_init);
module_exit(moxa_exit);

-static void moxa_close_port(struct moxa_port *ch)
+static void moxa_close_port(struct tty_struct *tty)
{
- moxa_shut_down(ch);
+ struct moxa_port *ch = tty->driver_data;
+ moxa_shut_down(tty);
MoxaPortFlushData(ch, 2);
ch->port.flags &= ~ASYNC_NORMAL_ACTIVE;
- ch->port.tty->driver_data = NULL;
- ch->port.tty = NULL;
+ tty->driver_data = NULL;
+ tty_port_tty_set(&ch->port, NULL);
}

static int moxa_block_till_ready(struct tty_struct *tty, struct file *filp,
@@ -1161,7 +1171,7 @@ static int moxa_open(struct tty_struct *tty, struct file *filp)
ch = &brd->ports[port % MAX_PORTS_PER_BOARD];
ch->port.count++;
tty->driver_data = ch;
- ch->port.tty = tty;
+ tty_port_tty_set(&ch->port, tty);
if (!(ch->port.flags & ASYNC_INITIALIZED)) {
ch->statusflags = 0;
moxa_set_tty_param(tty, tty->termios);
@@ -1179,7 +1189,7 @@ static int moxa_open(struct tty_struct *tty, struct file *filp)
if (retval) {
if (ch->port.count) /* 0 means already hung up... */
if (--ch->port.count == 0)
- moxa_close_port(ch);
+ moxa_close_port(tty);
} else
ch->port.flags |= ASYNC_NORMAL_ACTIVE;
mutex_unlock(&moxa_openlock);
@@ -1219,7 +1229,7 @@ static void moxa_close(struct tty_struct *tty, struct file *filp)
tty_wait_until_sent(tty, 30 * HZ); /* 30 seconds timeout */
}

- moxa_close_port(ch);
+ moxa_close_port(tty);
unlock:
mutex_unlock(&moxa_openlock);
}
@@ -1234,7 +1244,7 @@ static int moxa_write(struct tty_struct *tty,
return 0;

spin_lock_bh(&moxa_lock);
- len = MoxaPortWriteData(ch, buf, count);
+ len = MoxaPortWriteData(tty, buf, count);
spin_unlock_bh(&moxa_lock);

ch->statusflags |= LOWWAIT;
@@ -1409,7 +1419,7 @@ static void moxa_hangup(struct tty_struct *tty)
return;
}
ch->port.count = 0;
- moxa_close_port(ch);
+ moxa_close_port(tty);
mutex_unlock(&moxa_openlock);

wake_up_interruptible(&ch->port.open_wait);
@@ -1417,11 +1427,14 @@ static void moxa_hangup(struct tty_struct *tty)

static void moxa_new_dcdstate(struct moxa_port *p, u8 dcd)
{
+ struct tty_struct *tty;
dcd = !!dcd;

- if (dcd != p->DCDState && p->port.tty && C_CLOCAL(p->port.tty)) {
- if (!dcd)
- tty_hangup(p->port.tty);
+ if (dcd != p->DCDState) {
+ tty = tty_port_tty_get(&p->port);
+ if (tty && C_CLOCAL(tty) && !dcd)
+ tty_hangup(tty);
+ tty_kref_put(tty);
}
p->DCDState = dcd;
}
@@ -1429,7 +1442,7 @@ static void moxa_new_dcdstate(struct moxa_port *p, u8 dcd)
static int moxa_poll_port(struct moxa_port *p, unsigned int handle,
u16 __iomem *ip)
{
- struct tty_struct *tty = p->port.tty;
+ struct tty_struct *tty = tty_port_tty_get(&p->port);
void __iomem *ofsAddr;
unsigned int inited = p->port.flags & ASYNC_INITIALIZED;
u16 intr;
@@ -1476,6 +1489,7 @@ static int moxa_poll_port(struct moxa_port *p, unsigned int handle,
tty_insert_flip_char(tty, 0, TTY_BREAK);
tty_schedule_flip(tty);
}
+ tty_kref_put(tty);

if (intr & IntrLine)
moxa_new_dcdstate(p, readb(ofsAddr + FlagStat) & DCD_state);
@@ -1560,9 +1574,9 @@ static void moxa_setup_empty_event(struct tty_struct *tty)
spin_unlock_bh(&moxa_lock);
}

-static void moxa_shut_down(struct moxa_port *ch)
+static void moxa_shut_down(struct tty_struct *tty)
{
- struct tty_struct *tp = ch->port.tty;
+ struct moxa_port *ch = tty->driver_data;

if (!(ch->port.flags & ASYNC_INITIALIZED))
return;
@@ -1572,7 +1586,7 @@ static void moxa_shut_down(struct moxa_port *ch)
/*
* If we're a modem control device and HUPCL is on, drop RTS & DTR.
*/
- if (C_HUPCL(tp))
+ if (C_HUPCL(tty))
MoxaPortLineCtrl(ch, 0, 0);

spin_lock_bh(&moxa_lock);
@@ -1953,9 +1967,10 @@ static int MoxaPortLineStatus(struct moxa_port *port)
return val;
}

-static int MoxaPortWriteData(struct moxa_port *port,
+static int MoxaPortWriteData(struct tty_struct *tty,
const unsigned char *buffer, int len)
{
+ struct moxa_port *port = tty->driver_data;
void __iomem *baseAddr, *ofsAddr, *ofs;
unsigned int c, total;
u16 head, tail, tx_mask, spage, epage;


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