Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757805Ab3FDCuE (ORCPT ); Mon, 3 Jun 2013 22:50:04 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:42728 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755177Ab3FDCuA (ORCPT ); Mon, 3 Jun 2013 22:50:00 -0400 Date: Mon, 3 Jun 2013 19:49:59 -0700 From: Greg KH To: Tobias Winter , =?iso-8859-1?Q?Bj=F8rn?= Mork , Rob Landley Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] raise the maximum number of usb-serial devices to 512 Message-ID: <20130604024959.GA10697@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1369721825.2776.36@driftwood> <51A327A4.7020908@linuxdingsda.de> <87obbwbo8s.fsf@nemi.mork.no> <51A332E2.1090403@linuxdingsda.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5305 Lines: 184 On Mon, May 27, 2013 at 02:28:51PM +0200, Bj?rn Mork wrote: > But, IMHO, a nicer approach would be to make the allocation completely > dynamic, using e.g. the idr subsystem. Static tables are always feel > like straight jackets to me, no matter how big they are :) You are right, I didn't change the code to use idr (it predates idr by about a decade or so), because I thought we needed the "rage" logic that the usb-serial minor reservation does. But I'm not so sure anymore, so here's a patch to change to use the idr code, and should remove all minor number limitations (well 65k is the limit the tty core should be setting I think.) Tobias, can you test this patch out? Note, I only compiled it, did not get the chance to actually run it, so it might not work at all. thanks, greg k-h Subject: [PATCH] usb: serial: remove minor number limitation of 255 Signed-off-by: Greg Kroah-Hartman drivers/usb/serial/usb-serial.c | 86 +++++++++++++++++----------------------- 1 file changed, 38 insertions(+), 48 deletions(-) diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c index 4753c00..74b6f08 100644 --- a/drivers/usb/serial/usb-serial.c +++ b/drivers/usb/serial/usb-serial.c @@ -37,6 +37,7 @@ #include #include #include +#include #include "pl2303.h" #define DRIVER_AUTHOR "Greg Kroah-Hartman " @@ -49,7 +50,7 @@ drivers depend on it. */ -static struct usb_serial *serial_table[SERIAL_TTY_MINORS]; +static DEFINE_IDR(serial_minors); static DEFINE_MUTEX(table_lock); static LIST_HEAD(usb_serial_driver_list); @@ -61,59 +62,52 @@ static LIST_HEAD(usb_serial_driver_list); struct usb_serial *usb_serial_get_by_index(unsigned index) { struct usb_serial *serial; + struct usb_serial_port *port; mutex_lock(&table_lock); - serial = serial_table[index]; - - if (serial) { - mutex_lock(&serial->disc_mutex); - if (serial->disconnected) { - mutex_unlock(&serial->disc_mutex); - serial = NULL; - } else { - kref_get(&serial->kref); - } - } + port = idr_find(&serial_minors, index); mutex_unlock(&table_lock); + if (!port) + return NULL; + + serial = port->serial; + kref_get(&serial->kref); return serial; } -static struct usb_serial *get_free_serial(struct usb_serial *serial, - int num_ports, unsigned int *minor) +static int get_free_port(struct usb_serial_port *port) { - unsigned int i, j; - int good_spot; - - dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports); + int i; - *minor = 0; mutex_lock(&table_lock); - for (i = 0; i < SERIAL_TTY_MINORS; ++i) { - if (serial_table[i]) - continue; + i = idr_alloc(&serial_minors, port, 0, 0, GFP_KERNEL); + if (i < 0) + return -EEXIST; + port->number = i; + mutex_unlock(&table_lock); + return i; +} - good_spot = 1; - for (j = 1; j <= num_ports-1; ++j) - if ((i+j >= SERIAL_TTY_MINORS) || (serial_table[i+j])) { - good_spot = 0; - i += j; - break; - } - if (good_spot == 0) - continue; +static int get_free_serial(struct usb_serial *serial, int num_ports, + unsigned int *minor) +{ + unsigned int i; + unsigned int x; - *minor = i; - j = 0; - dev_dbg(&serial->interface->dev, "%s - minor base = %d\n", __func__, *minor); - for (i = *minor; (i < (*minor + num_ports)) && (i < SERIAL_TTY_MINORS); ++i) { - serial_table[i] = serial; - serial->port[j++]->number = i; - } - mutex_unlock(&table_lock); - return serial; + dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports); + + *minor = 0xffffffff; + for (i = 0; i < num_ports; ++i) { + x = get_free_port(serial->port[i]); + if (x < 0) + goto error; + if (*minor == 0xffffffff) + *minor = x; } - mutex_unlock(&table_lock); - return NULL; + return 0; +error: + // FIXME unwind the already allocated minors + return -ENODEV; } static void return_serial(struct usb_serial *serial) @@ -122,7 +116,7 @@ static void return_serial(struct usb_serial *serial) mutex_lock(&table_lock); for (i = 0; i < serial->num_ports; ++i) - serial_table[serial->minor + i] = NULL; + idr_remove(&serial_minors, serial->port[i]->number); mutex_unlock(&table_lock); } @@ -1041,7 +1035,7 @@ static int usb_serial_probe(struct usb_interface *interface, */ serial->disconnected = 1; - if (get_free_serial(serial, num_ports, &minor) == NULL) { + if (get_free_serial(serial, num_ports, &minor)) { dev_err(ddev, "No more free serial devices\n"); goto probe_error; } @@ -1225,7 +1219,6 @@ static struct usb_driver usb_serial_driver = { static int __init usb_serial_init(void) { - int i; int result; usb_serial_tty_driver = alloc_tty_driver(SERIAL_TTY_MINORS); @@ -1233,9 +1226,6 @@ static int __init usb_serial_init(void) return -ENOMEM; /* Initialize our global data */ - for (i = 0; i < SERIAL_TTY_MINORS; ++i) - serial_table[i] = NULL; - result = bus_register(&usb_serial_bus_type); if (result) { pr_err("%s - registering bus driver failed\n", __func__); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/