[PATCH] Char: isicom, eliminate spinlock recursion

Many spinlock recursion was in the isicom driver.  Eliminate it.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 51 insertions, 52 deletions

diff --git a/drivers/char/isicom.c b/drivers/char/isicom.c
index 5a747e68599..01084abffdd 100644
--- a/drivers/char/isicom.c
+++ b/drivers/char/isicom.c
@@ -230,6 +230,20 @@ 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;
@@ -276,69 +290,71 @@ 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;
@@ -355,35 +371,20 @@ 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);
 }
 
 /*
@@ -744,7 +745,7 @@ 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;
@@ -772,7 +773,6 @@ 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;
@@ -791,12 +791,11 @@ 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    */
@@ -821,10 +820,9 @@ 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)
@@ -857,7 +855,12 @@ 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;
@@ -983,28 +986,22 @@ 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;
@@ -1012,7 +1009,6 @@ 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
@@ -1258,10 +1254,12 @@ 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)
@@ -1271,6 +1269,7 @@ 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;
 }
@@ -1303,7 +1302,10 @@ 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;
 }
@@ -1384,6 +1386,7 @@ 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;
@@ -1392,7 +1395,9 @@ 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)) {
@@ -1469,11 +1474,15 @@ static void do_isicom_hangup(struct work_struct *work)
 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;
@@ -1578,16 +1587,6 @@ 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)
 {