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Message-id: <2249412545243025582@wsc.cz>
Date: Sat, 23 Dec 2006 20:46:35 +0100 (CET)
From: Jiri Slaby <jirislaby@...il.com>
To: Andrew Morton <akpm@...l.org>
Cc: <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/1] Char: isicom, eliminate spinlock recursion
isicom, eliminate spinlock recursion
Many spinlock recursion was in the isicom driver. Eliminate it.
Signed-off-by: Jiri Slaby <jirislaby@...il.com>
---
commit 59988b8c2d1ce45e5ccb715ac7ece78dfb73545a
tree d6060769defd71c77ffa340d579f95e24b783ebf
parent fe13ee556f3b973a3b27f154db9852766634d0d6
author Jiri Slaby <jirislaby@...il.com> Sat, 23 Dec 2006 20:43:42 +0059
committer Jiri Slaby <jirislaby@...il.com> Sat, 23 Dec 2006 20:43:42 +0059
drivers/char/isicom.c | 103 ++++++++++++++++++++++++-------------------------
1 files changed, 51 insertions(+), 52 deletions(-)
diff --git a/drivers/char/isicom.c b/drivers/char/isicom.c
index 0362740..26d3f78 100644
--- a/drivers/char/isicom.c
+++ b/drivers/char/isicom.c
@@ -228,6 +228,20 @@ static struct isi_port isi_ports[PORT_COUNT];
* it wants to talk.
*/
+static inline int WaitTillCardIsFree(u16 base)
+{
+ unsigned int count = 0;
+ unsigned int a = in_atomic(); /* do we run under spinlock? */
+
+ while (!(inw(base + 0xe) & 0x1) && count++ < 100)
+ if (a)
+ mdelay(1);
+ else
+ msleep(1);
+
+ return !(inw(base + 0xe) & 0x1);
+}
+
static int lock_card(struct isi_board *card)
{
char retries;
@@ -274,69 +288,71 @@ static void unlock_card(struct isi_board *card)
* ISI Card specific ops ...
*/
+/* card->lock HAS to be held */
static void raise_dtr(struct isi_port *port)
{
struct isi_board *card = port->card;
unsigned long base = card->base;
u16 channel = port->channel;
- if (!lock_card(card))
+ if (WaitTillCardIsFree(base))
return;
outw(0x8000 | (channel << card->shift_count) | 0x02, base);
outw(0x0504, base);
InterruptTheCard(base);
port->status |= ISI_DTR;
- unlock_card(card);
}
+/* card->lock HAS to be held */
static inline void drop_dtr(struct isi_port *port)
{
struct isi_board *card = port->card;
unsigned long base = card->base;
u16 channel = port->channel;
- if (!lock_card(card))
+ if (WaitTillCardIsFree(base))
return;
outw(0x8000 | (channel << card->shift_count) | 0x02, base);
outw(0x0404, base);
InterruptTheCard(base);
port->status &= ~ISI_DTR;
- unlock_card(card);
}
+/* card->lock HAS to be held */
static inline void raise_rts(struct isi_port *port)
{
struct isi_board *card = port->card;
unsigned long base = card->base;
u16 channel = port->channel;
- if (!lock_card(card))
+ if (WaitTillCardIsFree(base))
return;
outw(0x8000 | (channel << card->shift_count) | 0x02, base);
outw(0x0a04, base);
InterruptTheCard(base);
port->status |= ISI_RTS;
- unlock_card(card);
}
+
+/* card->lock HAS to be held */
static inline void drop_rts(struct isi_port *port)
{
struct isi_board *card = port->card;
unsigned long base = card->base;
u16 channel = port->channel;
- if (!lock_card(card))
+ if (WaitTillCardIsFree(base))
return;
outw(0x8000 | (channel << card->shift_count) | 0x02, base);
outw(0x0804, base);
InterruptTheCard(base);
port->status &= ~ISI_RTS;
- unlock_card(card);
}
+/* card->lock MUST NOT be held */
static inline void raise_dtr_rts(struct isi_port *port)
{
struct isi_board *card = port->card;
@@ -353,35 +369,20 @@ static inline void raise_dtr_rts(struct isi_port *port)
unlock_card(card);
}
+/* card->lock HAS to be held */
static void drop_dtr_rts(struct isi_port *port)
{
struct isi_board *card = port->card;
unsigned long base = card->base;
u16 channel = port->channel;
- if (!lock_card(card))
+ if (WaitTillCardIsFree(base))
return;
outw(0x8000 | (channel << card->shift_count) | 0x02, base);
outw(0x0c04, base);
InterruptTheCard(base);
port->status &= ~(ISI_RTS | ISI_DTR);
- unlock_card(card);
-}
-
-static inline void kill_queue(struct isi_port *port, short queue)
-{
- struct isi_board *card = port->card;
- unsigned long base = card->base;
- u16 channel = port->channel;
-
- if (!lock_card(card))
- return;
-
- outw(0x8000 | (channel << card->shift_count) | 0x02, base);
- outw((queue << 8) | 0x06, base);
- InterruptTheCard(base);
- unlock_card(card);
}
/*
@@ -727,7 +728,7 @@ static void isicom_config_port(struct isi_port *port)
else
raise_dtr(port);
- if (lock_card(card)) {
+ if (WaitTillCardIsFree(base) == 0) {
outw(0x8000 | (channel << shift_count) |0x03, base);
outw(linuxb_to_isib[baud] << 8 | 0x03, base);
channel_setup = 0;
@@ -755,7 +756,6 @@ static void isicom_config_port(struct isi_port *port)
}
outw(channel_setup, base);
InterruptTheCard(base);
- unlock_card(card);
}
if (C_CLOCAL(tty))
port->flags &= ~ASYNC_CHECK_CD;
@@ -774,12 +774,11 @@ static void isicom_config_port(struct isi_port *port)
if (I_IXOFF(tty))
flow_ctrl |= ISICOM_INITIATE_XONXOFF;
- if (lock_card(card)) {
+ if (WaitTillCardIsFree(base) == 0) {
outw(0x8000 | (channel << shift_count) |0x04, base);
outw(flow_ctrl << 8 | 0x05, base);
outw((STOP_CHAR(tty)) << 8 | (START_CHAR(tty)), base);
InterruptTheCard(base);
- unlock_card(card);
}
/* rx enabled -> enable port for rx on the card */
@@ -804,10 +803,9 @@ static inline void isicom_setup_board(struct isi_board *bp)
}
port = bp->ports;
bp->status |= BOARD_ACTIVE;
- spin_unlock_irqrestore(&bp->card_lock, flags);
for (channel = 0; channel < bp->port_count; channel++, port++)
drop_dtr_rts(port);
- return;
+ spin_unlock_irqrestore(&bp->card_lock, flags);
}
static int isicom_setup_port(struct isi_port *port)
@@ -840,7 +838,12 @@ static int isicom_setup_port(struct isi_port *port)
port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
/* discard any residual data */
- kill_queue(port, ISICOM_KILLTX | ISICOM_KILLRX);
+ if (WaitTillCardIsFree(card->base) == 0) {
+ outw(0x8000 | (port->channel << card->shift_count) | 0x02,
+ card->base);
+ outw(((ISICOM_KILLTX | ISICOM_KILLRX) << 8) | 0x06, card->base);
+ InterruptTheCard(card->base);
+ }
isicom_config_port(port);
port->flags |= ASYNC_INITIALIZED;
@@ -966,28 +969,22 @@ static int isicom_open(struct tty_struct *tty, struct file *filp)
static inline void isicom_shutdown_board(struct isi_board *bp)
{
- unsigned long flags;
-
- spin_lock_irqsave(&bp->card_lock, flags);
if (bp->status & BOARD_ACTIVE) {
bp->status &= ~BOARD_ACTIVE;
}
- spin_unlock_irqrestore(&bp->card_lock, flags);
}
+/* card->lock HAS to be held */
static void isicom_shutdown_port(struct isi_port *port)
{
struct isi_board *card = port->card;
struct tty_struct *tty;
- unsigned long flags;
tty = port->tty;
- spin_lock_irqsave(&card->card_lock, flags);
- if (!(port->flags & ASYNC_INITIALIZED)) {
- spin_unlock_irqrestore(&card->card_lock, flags);
+ if (!(port->flags & ASYNC_INITIALIZED))
return;
- }
+
if (port->xmit_buf) {
free_page((unsigned long) port->xmit_buf);
port->xmit_buf = NULL;
@@ -995,7 +992,6 @@ static void isicom_shutdown_port(struct isi_port *port)
port->flags &= ~ASYNC_INITIALIZED;
/* 3rd October 2000 : Vinayak P Risbud */
port->tty = NULL;
- spin_unlock_irqrestore(&card->card_lock, flags);
/*Fix done by Anil .S on 30-04-2001
remote login through isi port has dtr toggle problem
@@ -1241,10 +1237,12 @@ static int isicom_tiocmset(struct tty_struct *tty, struct file *file,
unsigned int set, unsigned int clear)
{
struct isi_port *port = tty->driver_data;
+ unsigned long flags;
if (isicom_paranoia_check(port, tty->name, "isicom_ioctl"))
return -ENODEV;
+ spin_lock_irqsave(&port->card->card_lock, flags);
if (set & TIOCM_RTS)
raise_rts(port);
if (set & TIOCM_DTR)
@@ -1254,6 +1252,7 @@ static int isicom_tiocmset(struct tty_struct *tty, struct file *file,
drop_rts(port);
if (clear & TIOCM_DTR)
drop_dtr(port);
+ spin_unlock_irqrestore(&port->card->card_lock, flags);
return 0;
}
@@ -1286,7 +1285,10 @@ static int isicom_set_serial_info(struct isi_port *port,
(newinfo.flags & ASYNC_FLAGS));
}
if (reconfig_port) {
+ unsigned long flags;
+ spin_lock_irqsave(&port->card->card_lock, flags);
isicom_config_port(port);
+ spin_unlock_irqrestore(&port->card->card_lock, flags);
}
return 0;
}
@@ -1367,6 +1369,7 @@ static void isicom_set_termios(struct tty_struct *tty,
struct ktermios *old_termios)
{
struct isi_port *port = tty->driver_data;
+ unsigned long flags;
if (isicom_paranoia_check(port, tty->name, "isicom_set_termios"))
return;
@@ -1375,7 +1378,9 @@ static void isicom_set_termios(struct tty_struct *tty,
tty->termios->c_iflag == old_termios->c_iflag)
return;
+ spin_lock_irqsave(&port->card->card_lock, flags);
isicom_config_port(port);
+ spin_unlock_irqrestore(&port->card->card_lock, flags);
if ((old_termios->c_cflag & CRTSCTS) &&
!(tty->termios->c_cflag & CRTSCTS)) {
@@ -1441,11 +1446,15 @@ static void isicom_start(struct tty_struct *tty)
static void isicom_hangup(struct tty_struct *tty)
{
struct isi_port *port = tty->driver_data;
+ unsigned long flags;
if (isicom_paranoia_check(port, tty->name, "isicom_hangup"))
return;
+ spin_lock_irqsave(&port->card->card_lock, flags);
isicom_shutdown_port(port);
+ spin_unlock_irqrestore(&port->card->card_lock, flags);
+
port->count = 0;
port->flags &= ~ASYNC_NORMAL_ACTIVE;
port->tty = NULL;
@@ -1550,16 +1559,6 @@ end:
return retval;
}
-static inline int WaitTillCardIsFree(u16 base)
-{
- unsigned long count = 0;
-
- while (!(inw(base + 0xe) & 0x1) && count++ < 100)
- msleep(5);
-
- return !(inw(base + 0xe) & 0x1);
-}
-
static int __devinit load_firmware(struct pci_dev *pdev,
const unsigned int index, const unsigned int signature)
{
-
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