tty/serial: lay the foundations for the next set of reworks

- Stop drivers calling their own flush method indirectly, it obfuscates code
  and it will change soon anyway

- A few more lock_kernel paths temporarily needed in some driver internal
  waiting code

- Remove private put_char method that does a write call for one char - we
  have that anyway

- Most but not yet all of the termios copy under lock fixing (some has other
  dependencies to follow)

- Note a few locking bugs in drivers found in the process

- Kill remaining [ab]users of TIOCG/SSOFTCAR in the driver, these must go to
  fix the termios locking

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/amiserial.c

@@ -1505,8 +1505,7 @@ static void rs_close(struct tty_struct *tty, struct file * filp)
 		rs_wait_until_sent(tty, info->timeout);
 	}
 	shutdown(info);
-	if (tty->driver->flush_buffer)
-		tty->driver->flush_buffer(tty);
+	rs_flush_buffer(tty);
 
 	tty_ldisc_flush(tty);
 	tty->closing = 0;
@@ -1539,6 +1538,8 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 		return; /* Just in case.... */
 
 	orig_jiffies = jiffies;
+
+	lock_kernel();
 	/*
 	 * Set the check interval to be 1/5 of the estimated time to
 	 * send a single character, and make it at least 1.  The check
@@ -1579,6 +1580,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 			break;
 	}
 	__set_current_state(TASK_RUNNING);
+	unlock_kernel();
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
 	printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
 #endif

drivers/char/cyclades.c

@@ -2522,6 +2522,7 @@ static void cy_wait_until_sent(struct tty_struct *tty, int timeout)
 		return;		/* Just in case.... */
 
 	orig_jiffies = jiffies;
+	lock_kernel();
 	/*
 	 * Set the check interval to be 1/5 of the estimated time to
 	 * send a single character, and make it at least 1.  The check
@@ -2573,11 +2574,47 @@ static void cy_wait_until_sent(struct tty_struct *tty, int timeout)
 	}
 	/* Run one more char cycle */
 	msleep_interruptible(jiffies_to_msecs(char_time * 5));
+	unlock_kernel();
 #ifdef CY_DEBUG_WAIT_UNTIL_SENT
 	printk(KERN_DEBUG "Clean (jiff=%lu)...done\n", jiffies);
 #endif
 }
 
+static void cy_flush_buffer(struct tty_struct *tty)
+{
+	struct cyclades_port *info = tty->driver_data;
+	struct cyclades_card *card;
+	int channel, retval;
+	unsigned long flags;
+
+#ifdef CY_DEBUG_IO
+	printk(KERN_DEBUG "cyc:cy_flush_buffer ttyC%d\n", info->line);
+#endif
+
+	if (serial_paranoia_check(info, tty->name, "cy_flush_buffer"))
+		return;
+
+	card = info->card;
+	channel = info->line - card->first_line;
+
+	spin_lock_irqsave(&card->card_lock, flags);
+	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
+	spin_unlock_irqrestore(&card->card_lock, flags);
+
+	if (IS_CYC_Z(*card)) {	/* If it is a Z card, flush the on-board
+					   buffers as well */
+		spin_lock_irqsave(&card->card_lock, flags);
+		retval = cyz_issue_cmd(card, channel, C_CM_FLUSH_TX, 0L);
+		if (retval != 0) {
+			printk(KERN_ERR "cyc: flush_buffer retval on ttyC%d "
+				"was %x\n", info->line, retval);
+		}
+		spin_unlock_irqrestore(&card->card_lock, flags);
+	}
+	tty_wakeup(tty);
+}				/* cy_flush_buffer */
+
+
 /*
  * This routine is called when a particular tty device is closed.
  */
@@ -2689,8 +2726,7 @@ static void cy_close(struct tty_struct *tty, struct file *filp)
 
 	spin_unlock_irqrestore(&card->card_lock, flags);
 	shutdown(info);
-	if (tty->driver->flush_buffer)
-		tty->driver->flush_buffer(tty);
+	cy_flush_buffer(tty);
 	tty_ldisc_flush(tty);
 	spin_lock_irqsave(&card->card_lock, flags);
 
@@ -2881,6 +2917,7 @@ static int cy_chars_in_buffer(struct tty_struct *tty)
 		int char_count;
 		__u32 tx_put, tx_get, tx_bufsize;
 
+		lock_kernel();
 		firm_id = card->base_addr + ID_ADDRESS;
 		zfw_ctrl = card->base_addr +
 			(readl(&firm_id->zfwctrl_addr) & 0xfffff);
@@ -2898,6 +2935,7 @@ static int cy_chars_in_buffer(struct tty_struct *tty)
 		printk(KERN_DEBUG "cyc:cy_chars_in_buffer ttyC%d %d\n",
 			info->line, info->xmit_cnt + char_count);
 #endif
+		unlock_kernel();
 		return info->xmit_cnt + char_count;
 	}
 #endif				/* Z_EXT_CHARS_IN_BUFFER */
@@ -4271,40 +4309,6 @@ static void cy_start(struct tty_struct *tty)
 	}
 }				/* cy_start */
 
-static void cy_flush_buffer(struct tty_struct *tty)
-{
-	struct cyclades_port *info = tty->driver_data;
-	struct cyclades_card *card;
-	int channel, retval;
-	unsigned long flags;
-
-#ifdef CY_DEBUG_IO
-	printk(KERN_DEBUG "cyc:cy_flush_buffer ttyC%d\n", info->line);
-#endif
-
-	if (serial_paranoia_check(info, tty->name, "cy_flush_buffer"))
-		return;
-
-	card = info->card;
-	channel = info->line - card->first_line;
-
-	spin_lock_irqsave(&card->card_lock, flags);
-	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
-	spin_unlock_irqrestore(&card->card_lock, flags);
-
-	if (IS_CYC_Z(*card)) {	/* If it is a Z card, flush the on-board
-					   buffers as well */
-		spin_lock_irqsave(&card->card_lock, flags);
-		retval = cyz_issue_cmd(card, channel, C_CM_FLUSH_TX, 0L);
-		if (retval != 0) {
-			printk(KERN_ERR "cyc: flush_buffer retval on ttyC%d "
-				"was %x\n", info->line, retval);
-		}
-		spin_unlock_irqrestore(&card->card_lock, flags);
-	}
-	tty_wakeup(tty);
-}				/* cy_flush_buffer */
-
 /*
  * cy_hangup() --- called by tty_hangup() when a hangup is signaled.
  */

drivers/char/epca.c

@@ -157,7 +157,6 @@ static void epca_error(int, char *);
 static void pc_close(struct tty_struct *, struct file *);
 static void shutdown(struct channel *);
 static void pc_hangup(struct tty_struct *);
-static void pc_put_char(struct tty_struct *, unsigned char);
 static int pc_write_room(struct tty_struct *);
 static int pc_chars_in_buffer(struct tty_struct *);
 static void pc_flush_buffer(struct tty_struct *);
@@ -459,8 +458,7 @@ static void pc_close(struct tty_struct *tty, struct file *filp)
 			setup_empty_event(tty, ch);
 			tty_wait_until_sent(tty, 3000); /* 30 seconds timeout */
 		}
-		if (tty->driver->flush_buffer)
-			tty->driver->flush_buffer(tty);
+		pc_flush_buffer(tty);
 
 		tty_ldisc_flush(tty);
 		shutdown(ch);
@@ -532,8 +530,7 @@ static void pc_hangup(struct tty_struct *tty)
 	if ((ch = verifyChannel(tty)) != NULL) {
 		unsigned long flags;
 
-		if (tty->driver->flush_buffer)
-			tty->driver->flush_buffer(tty);
+		pc_flush_buffer(tty);
 		tty_ldisc_flush(tty);
 		shutdown(ch);
 
@@ -645,11 +642,6 @@ static int pc_write(struct tty_struct *tty,
 	return amountCopied;
 }
 
-static void pc_put_char(struct tty_struct *tty, unsigned char c)
-{
-	pc_write(tty, &c, 1);
-}
-
 static int pc_write_room(struct tty_struct *tty)
 {
 	int remain;
@@ -1035,7 +1027,6 @@ static const struct tty_operations pc_ops = {
 	.flush_buffer = pc_flush_buffer,
 	.chars_in_buffer = pc_chars_in_buffer,
 	.flush_chars = pc_flush_chars,
-	.put_char = pc_put_char,
 	.ioctl = pc_ioctl,
 	.set_termios = pc_set_termios,
 	.stop = pc_stop,

drivers/char/esp.c

@@ -1994,8 +1994,7 @@ static void rs_close(struct tty_struct *tty, struct file * filp)
 		rs_wait_until_sent(tty, info->timeout);
 	}
 	shutdown(info);
-	if (tty->driver->flush_buffer)
-		tty->driver->flush_buffer(tty);
+	rs_flush_buffer(tty);
 	tty_ldisc_flush(tty);
 	tty->closing = 0;
 	info->tty = NULL;

drivers/char/generic_serial.c

@@ -586,8 +586,7 @@ void gs_close(struct tty_struct * tty, struct file * filp)
 
 	port->flags &= ~GS_ACTIVE;
 
-	if (tty->driver->flush_buffer)
-		tty->driver->flush_buffer(tty);
+	gs_flush_buffer(tty);
 
 	tty_ldisc_flush(tty);
 	tty->closing = 0;

drivers/char/isicom.c

@@ -1012,6 +1012,22 @@ static void isicom_shutdown_port(struct isi_port *port)
 	}
 }
 
+static void isicom_flush_buffer(struct tty_struct *tty)
+{
+	struct isi_port *port = tty->driver_data;
+	struct isi_board *card = port->card;
+	unsigned long flags;
+
+	if (isicom_paranoia_check(port, tty->name, "isicom_flush_buffer"))
+		return;
+
+	spin_lock_irqsave(&card->card_lock, flags);
+	port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
+	spin_unlock_irqrestore(&card->card_lock, flags);
+
+	tty_wakeup(tty);
+}
+
 static void isicom_close(struct tty_struct *tty, struct file *filp)
 {
 	struct isi_port *port = tty->driver_data;
@@ -1065,8 +1081,7 @@ static void isicom_close(struct tty_struct *tty, struct file *filp)
 	isicom_shutdown_port(port);
 	spin_unlock_irqrestore(&card->card_lock, flags);
 
-	if (tty->driver->flush_buffer)
-		tty->driver->flush_buffer(tty);
+	isicom_flush_buffer(tty);
 	tty_ldisc_flush(tty);
 
 	spin_lock_irqsave(&card->card_lock, flags);
@@ -1447,22 +1462,6 @@ static void isicom_hangup(struct tty_struct *tty)
 	wake_up_interruptible(&port->open_wait);
 }
 
-/* flush_buffer et all */
-static void isicom_flush_buffer(struct tty_struct *tty)
-{
-	struct isi_port *port = tty->driver_data;
-	struct isi_board *card = port->card;
-	unsigned long flags;
-
-	if (isicom_paranoia_check(port, tty->name, "isicom_flush_buffer"))
-		return;
-
-	spin_lock_irqsave(&card->card_lock, flags);
-	port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
-	spin_unlock_irqrestore(&card->card_lock, flags);
-
-	tty_wakeup(tty);
-}
 
 /*
  * Driver init and deinit functions

drivers/char/moxa.c

@@ -1280,6 +1280,7 @@ static int moxa_chars_in_buffer(struct tty_struct *tty)
 	 */
 	if (ch == NULL)
 		return 0;
+	lock_kernel();
 	chars = MoxaPortTxQueue(ch);
 	if (chars) {
 		/*
@@ -1289,6 +1290,7 @@ static int moxa_chars_in_buffer(struct tty_struct *tty)
 		if (!(ch->statusflags & EMPTYWAIT))
 			moxa_setup_empty_event(tty);
 	}
+	unlock_kernel();
 	return chars;
 }
 

drivers/char/mxser.c

@@ -927,6 +927,27 @@ static int mxser_open(struct tty_struct *tty, struct file *filp)
 	return 0;
 }
 
+static void mxser_flush_buffer(struct tty_struct *tty)
+{
+	struct mxser_port *info = tty->driver_data;
+	char fcr;
+	unsigned long flags;
+
+
+	spin_lock_irqsave(&info->slock, flags);
+	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
+
+	fcr = inb(info->ioaddr + UART_FCR);
+	outb((fcr | UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT),
+		info->ioaddr + UART_FCR);
+	outb(fcr, info->ioaddr + UART_FCR);
+
+	spin_unlock_irqrestore(&info->slock, flags);
+
+	tty_wakeup(tty);
+}
+
+
 /*
  * This routine is called when the serial port gets closed.  First, we
  * wait for the last remaining data to be sent.  Then, we unlink its
@@ -1013,9 +1034,7 @@ static void mxser_close(struct tty_struct *tty, struct file *filp)
 	}
 	mxser_shutdown(info);
 
-	if (tty->driver->flush_buffer)
-		tty->driver->flush_buffer(tty);
-
+	mxser_flush_buffer(tty);
 	tty_ldisc_flush(tty);
 
 	tty->closing = 0;
@@ -1142,26 +1161,6 @@ static int mxser_chars_in_buffer(struct tty_struct *tty)
 	return info->xmit_cnt;
 }
 
-static void mxser_flush_buffer(struct tty_struct *tty)
-{
-	struct mxser_port *info = tty->driver_data;
-	char fcr;
-	unsigned long flags;
-
-
-	spin_lock_irqsave(&info->slock, flags);
-	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
-
-	fcr = inb(info->ioaddr + UART_FCR);
-	outb((fcr | UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT),
-		info->ioaddr + UART_FCR);
-	outb(fcr, info->ioaddr + UART_FCR);
-
-	spin_unlock_irqrestore(&info->slock, flags);
-
-	tty_wakeup(tty);
-}
-
 /*
  * ------------------------------------------------------------
  * friends of mxser_ioctl()
@@ -1992,6 +1991,7 @@ static void mxser_wait_until_sent(struct tty_struct *tty, int timeout)
 		timeout, char_time);
 	printk("jiff=%lu...", jiffies);
 #endif
+	lock_kernel();
 	while (!((lsr = inb(info->ioaddr + UART_LSR)) & UART_LSR_TEMT)) {
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
 		printk("lsr = %d (jiff=%lu)...", lsr, jiffies);
@@ -2003,6 +2003,7 @@ static void mxser_wait_until_sent(struct tty_struct *tty, int timeout)
 			break;
 	}
 	set_current_state(TASK_RUNNING);
+	unlock_kernel();
 
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
 	printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);