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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: [PATCH 55/80] tty: Move parts of tty_init_dev into new functions
Date: Mon, 13 Oct 2008 10:41:51 +0100	[thread overview]
Message-ID: <20081013094147.21645.83999.stgit@localhost.localdomain> (raw)
In-Reply-To: <20081013092758.21645.2359.stgit@localhost.localdomain>

From: Sukadev Bhattiprolu <sukadev@us.ibm.com>

Move the 'find-tty' and 'fast-track-open' parts of init_dev() to
separate functions.

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.com>
---

 drivers/char/tty_io.c |  139 +++++++++++++++++++++++++++++++------------------
 1 files changed, 87 insertions(+), 52 deletions(-)


diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index fdcc43c..a540849 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1204,6 +1204,80 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p)
 	sprintf(p, "%s%d", driver->name, index + driver->name_base);
 }
 
+/*
+ * 	find_tty() - find an existing tty, if any
+ * 	@driver: the driver for the tty
+ * 	@idx:	 the minor number
+ *
+ * 	Return the tty, if found or ERR_PTR() otherwise.
+ *
+ * 	Locking: tty_mutex must be held. If tty is found, the mutex must
+ * 		 be held until the 'fast-open' is also done.
+ */
+struct tty_struct *find_tty(struct tty_driver *driver, int idx)
+{
+	struct tty_struct *tty;
+
+	/* check whether we're reopening an existing tty */
+	if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
+		tty = devpts_get_tty(idx);
+		/*
+		 * If we don't have a tty here on a slave open, it's because
+		 * the master already started the close process and there's
+		 * no relation between devpts file and tty anymore.
+		 */
+		if (!tty && driver->subtype == PTY_TYPE_SLAVE)
+			return ERR_PTR(-EIO);
+
+		/*
+		 * tty is safe on because we are called with tty_mutex held
+		 * and release_dev() won't change tty->count or tty->flags
+		 * without grabbing tty_mutex.
+		 */
+		if (tty && driver->subtype == PTY_TYPE_MASTER)
+			tty = tty->link;
+	} else
+		tty = driver->ttys[idx];
+	return tty;
+}
+
+/*
+ * 	fast_tty_open()	- fast re-open of an open tty
+ * 	@tty	- the tty to open
+ *
+ * 	Return 0 on success, -errno on error.
+ *
+ * 	Locking: tty_mutex must be held from the time the tty was found
+ * 		 till this open completes.
+ */
+static int fast_tty_open(struct tty_struct *tty)
+{
+	struct tty_driver *driver = tty->driver;
+
+	if (test_bit(TTY_CLOSING, &tty->flags))
+		return -EIO;
+
+	if (driver->type == TTY_DRIVER_TYPE_PTY &&
+	    driver->subtype == PTY_TYPE_MASTER) {
+		/*
+		 * special case for PTY masters: only one open permitted,
+		 * and the slave side open count is incremented as well.
+		 */
+		if (tty->count)
+			return -EIO;
+
+		tty->link->count++;
+	}
+	tty->count++;
+	tty->driver = driver; /* N.B. why do this every time?? */
+
+	/* FIXME */
+	if (!test_bit(TTY_LDISC, &tty->flags))
+		printk(KERN_ERR "fast_tty_open: no ldisc\n");
+
+	return 0;
+}
+
 /**
  *	tty_init_dev		-	initialise a tty device
  *	@driver: tty driver we are opening a device on
@@ -1238,29 +1312,21 @@ int tty_init_dev(struct tty_driver *driver, int idx,
 	int retval = 0;
 
 	/* check whether we're reopening an existing tty */
-	if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
-		tty = devpts_get_tty(idx);
-		/*
-		 * If we don't have a tty here on a slave open, it's because
-		 * the master already started the close process and there's
-		 * no relation between devpts file and tty anymore.
-		 */
-		if (!tty && driver->subtype == PTY_TYPE_SLAVE) {
-			retval = -EIO;
-			goto end_init;
-		}
-		/*
-		 * It's safe from now on because tty_init_dev() is called with
-		 * tty_mutex held and tty_release_dev() won't change tty->count
-		 * or tty->flags without having to grab tty_mutex
-		 */
-		if (tty && driver->subtype == PTY_TYPE_MASTER)
-			tty = tty->link;
-	} else {
-		tty = driver->ttys[idx];
+	tty = find_tty(driver, idx);
+	if (IS_ERR(tty)) {
+		retval = PTR_ERR(tty);
+		goto end_init;
+	}
+
+	if (tty) {
+		retval = fast_tty_open(tty);
+		if (retval)
+			return retval;
+		*ret_tty = tty;
+		return 0;
 	}
-	if (tty) goto fast_track;
 
+	/* Check if pty master is being opened multiple times */
 	if (driver->subtype == PTY_TYPE_MASTER &&
 		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
 		retval = -EIO;
@@ -1400,37 +1466,6 @@ int tty_init_dev(struct tty_driver *driver, int idx,
 
 	if (retval)
 		goto release_mem_out;
-	goto success;
-
-	/*
-	 * This fast open can be used if the tty is already open.
-	 * No memory is allocated, and the only failures are from
-	 * attempting to open a closing tty or attempting multiple
-	 * opens on a pty master.
-	 */
-fast_track:
-	if (test_bit(TTY_CLOSING, &tty->flags)) {
-		retval = -EIO;
-		goto end_init;
-	}
-	if (driver->type == TTY_DRIVER_TYPE_PTY &&
-	    driver->subtype == PTY_TYPE_MASTER) {
-		/*
-		 * special case for PTY masters: only one open permitted,
-		 * and the slave side open count is incremented as well.
-		 */
-		if (tty->count) {
-			retval = -EIO;
-			goto end_init;
-		}
-		tty->link->count++;
-	}
-	tty->count++;
-	tty->driver = driver; /* N.B. why do this every time?? */
-
-	/* FIXME */
-	if (!test_bit(TTY_LDISC, &tty->flags))
-		printk(KERN_ERR "tty_init_dev but no ldisc\n");
 success:
 	*ret_tty = tty;
 


  parent reply	other threads:[~2008-10-13  9:54 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-13  9:31 [PATCH 00/80] TTY updates for 2.6.28 Alan Cox
2008-10-13  9:31 ` [PATCH 01/80] drivers/serial/crisv10.c: add missing put_tty_driver Alan Cox
2008-10-13  9:31 ` [PATCH 02/80] drivers/char/hvc_console.c: adjust call to put_tty_driver Alan Cox
2008-10-13  9:31 ` [PATCH 03/80] coldfire: scheduled SERIAL_COLDFIRE removal Alan Cox
2008-10-13  9:32 ` [PATCH 04/80] epca: call tty_port_init Alan Cox
2008-10-13  9:32 ` [PATCH 05/80] Blackfin Serial Driver: use __initdata for data, not __init Alan Cox
2008-10-13  9:32 ` [PATCH 06/80] Blackfin Serial Driver: Fix bug - should suspend/resume/remove all uart ports Alan Cox
2008-10-13  9:33 ` [PATCH 07/80] Blackfin Serial Driver: trim trailing whitespace -- no functional changes Alan Cox
2008-10-13  9:33 ` [PATCH 08/80] Blackfin Serial Driver: move common variables out of serial headers and into the serial driver Alan Cox
2008-10-13  9:33 ` [PATCH 09/80] Blackfin Serial Driver: Remove useless stop Alan Cox
2008-10-13  9:33 ` [PATCH 10/80] Blackfin Serial Driver: Fix bug - Don't call tx_stop in tx_transfer Alan Cox
2008-10-13  9:33 ` [PATCH 11/80] Blackfin Serial Driver: Fix bug - ircp fails on sir over Blackfin UART Alan Cox
2008-10-13  9:33 ` [PATCH 12/80] Blackfin Serial Driver: Fix bug - request UART2/3 peripheral mapped interrupts in PIO mode Alan Cox
2008-10-13  9:34 ` [PATCH 13/80] Fix oti6858 debug level Alan Cox
2008-10-13  9:34 ` [PATCH 14/80] Char: cyclades. remove bogus iomap Alan Cox
2008-10-13  9:34 ` [PATCH 15/80] Char: sx, fix io unmapping Alan Cox
2008-10-13  9:34 ` [PATCH 16/80] Char: merge ip2main and ip2base Alan Cox
2008-10-13  9:34 ` [PATCH 17/80] ip2, cleanup globals Alan Cox
2008-10-13  9:34 ` [PATCH 18/80] ip2, fix sparse warnings Alan Cox
2008-10-13  9:34 ` [PATCH 19/80] ip2, init/deinit cleanup Alan Cox
2008-10-13  9:35 ` [PATCH 20/80] ip2: avoid add_timer with pending timer Alan Cox
2008-10-13  9:35 ` [PATCH 21/80] audit: Handle embedded NUL in TTY input auditing Alan Cox
2008-10-13  9:35 ` [PATCH 22/80] serial: Make uart_port's ioport "unsigned long" Alan Cox
2008-10-13  9:35 ` [PATCH 23/80] nozomi: Fix close on error Alan Cox
2008-10-13  9:35 ` [PATCH 24/80] serial-make-uart_ports-ioport-unsigned-long-fix Alan Cox
2008-10-13  9:35 ` [PATCH 25/80] usb: fix pl2303 initialization Alan Cox
2008-10-13  9:36 ` [PATCH 26/80] ftdi: A few errors are err() that should be debug which causes much spewage Alan Cox
2008-10-13  9:36 ` [PATCH 27/80] serial_8250: pci_enable_device fail is not fully handled Alan Cox
2008-10-13  9:36 ` [PATCH 28/80] 8250: remove a few inlines of dubious value Alan Cox
2008-10-13  9:36 ` [PATCH 29/80] serial: allow 8250 to be used on sparc Alan Cox
2008-10-13  9:36 ` [PATCH 30/80] tty: move tioclinux from a special case Alan Cox
2008-10-13  9:36 ` [PATCH 31/80] uml: small cleanups and note bugs to be dealt with by uml authors Alan Cox
2008-10-13  9:36 ` [PATCH 32/80] tty: split the buffering from tty_io Alan Cox
2008-10-13  9:37 ` [PATCH 33/80] tty: Split tty_port into its own file Alan Cox
2008-10-13  9:37 ` [PATCH 34/80] pps: Reserve a line discipline number for PPS Alan Cox
2008-10-13  9:37 ` [PATCH 35/80] tty: Add a kref count Alan Cox
2008-10-13  9:37 ` [PATCH 36/80] tty: use krefs to protect driver module counts Alan Cox
2008-10-13  9:37 ` [PATCH 37/80] tty: Cris has a nice RS485 ioctl so we should steal it Alan Cox
2008-10-13  9:38 ` [PATCH 38/80] tty: ipw need reworking Alan Cox
2008-10-13  9:38 ` [PATCH 39/80] tty: Add termiox Alan Cox
2008-10-13  9:38 ` [PATCH 40/80] tty: Termios locking - sort out real_tty confusions and lock reads Alan Cox
2008-10-13  9:39 ` [PATCH 41/80] tty: compare the tty winsize Alan Cox
2008-10-13  9:39 ` [PATCH 42/80] tty: Make get_current_tty use a kref Alan Cox
2008-10-13  9:39 ` [PATCH 43/80] tty: Move tty_write_message out of kernel/printk Alan Cox
2008-10-13  9:39 ` [PATCH 44/80] tty: usb-serial krefs Alan Cox
2008-10-13  9:39 ` [PATCH 45/80] tty: kref usage for isicom and moxa Alan Cox
2008-10-13  9:40 ` [PATCH 46/80] stallion: Use krefs Alan Cox
2008-10-13  9:40 ` [PATCH 47/80] mxser: Switch to kref tty Alan Cox
2008-10-13  9:40 ` [PATCH 48/80] tty: the vhangup syscall is racy Alan Cox
2008-10-13  9:40 ` [PATCH 49/80] tty: Redo current tty locking Alan Cox
2008-10-13  9:40 ` [PATCH 50/80] tty: Fix abusers of current->sighand->tty Alan Cox
2008-10-13  9:41 ` [PATCH 51/80] pty: If the administrator creates a device for a ptmx slave we should not error Alan Cox
2008-10-13  9:41 ` [PATCH 52/80] vt: remove bogus lock dropping Alan Cox
2008-10-13  9:41 ` [PATCH 53/80] tty: shutdown method Alan Cox
2008-10-13  9:41 ` [PATCH 54/80] tty: Remove more special casing and out of place code Alan Cox
2008-10-13  9:41 ` Alan Cox [this message]
2008-10-13  9:42 ` [PATCH 56/80] tty: Clean up the tty_init_dev changes further Alan Cox
2008-10-13  9:42 ` [PATCH 57/80] tty: kref the tty driver object Alan Cox
2008-10-13  9:42 ` [PATCH 58/80] tty: More driver operations Alan Cox
2008-10-13  9:42 ` [PATCH 59/80] tty: Finish fixing up the init_dev interface to use ERR_PTR Alan Cox
2008-10-13  9:42 ` [PATCH 60/80] tty: extract the pty init time special cases Alan Cox
2008-10-13  9:42 ` [PATCH 61/80] Move tty lookup/reopen to caller Alan Cox
2008-10-13  9:42 ` [PATCH 62/80] Add an instance parameter devpts interfaces Alan Cox
2008-10-13  9:43 ` [PATCH 63/80] Simplify devpts_get_tty() Alan Cox
2008-10-13  9:43 ` [PATCH 64/80] Simplify devpts_pty_new() Alan Cox
2008-10-13  9:43 ` [PATCH 65/80] Simplify devpts_pty_kill Alan Cox
2008-10-13  9:43 ` [PATCH 66/80] pty: Coding style and polish Alan Cox
2008-10-13  9:43 ` [PATCH 67/80] pty: Fix allocation failure double free Alan Cox
2008-10-13  9:43 ` [PATCH 68/80] pty: simplify unix98 allocation Alan Cox
2008-10-13  9:44 ` [PATCH 69/80] tty: simplify ktermios allocation Alan Cox
2008-10-13  9:44 ` [PATCH 70/80] tty: some ICANON magic is in the wrong places Alan Cox
2008-10-13  9:44 ` [PATCH 71/80] tty: Fallout from tty-move-canon-specials Alan Cox
2008-10-13  9:44 ` [PATCH 72/80] tty: fix up gigaset a bit Alan Cox
2008-10-16 15:50   ` Tilman Schmidt
2008-10-17 11:40     ` Alan Cox
2008-10-19 12:28       ` Tilman Schmidt
2008-10-22  9:00         ` Alan Cox
2008-10-24 11:21           ` Tilman Schmidt
2008-10-13  9:44 ` [PATCH 73/80] tty: Remove lots of NULL checks Alan Cox
2008-10-13  9:45 ` [PATCH 74/80] tty: Minor tidyups and document fixes for n_tty Alan Cox
2008-10-13  9:45 ` [PATCH 75/80] applicom: Fix an unchecked user ioctl range and an error return Alan Cox
2008-10-13  9:45 ` [PATCH 76/80] serial: fix device name reporting when minor space is shared between drivers Alan Cox
2008-10-13  9:45 ` [PATCH 77/80] tty: tty_io.c shadows sparse fix Alan Cox
2008-10-13  9:45 ` [PATCH 78/80] fs3270: remove extra locks Alan Cox
2008-10-13  9:46 ` [PATCH 79/80] fs3270: Correct error returns Alan Cox
2008-10-13  9:46 ` [PATCH 80/80] tty: rename the remaining oddly named n_tty functions Alan Cox

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