From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753757AbcKNCFW (ORCPT ); Sun, 13 Nov 2016 21:05:22 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45396 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752905AbcKNCEU (ORCPT ); Sun, 13 Nov 2016 21:04:20 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Dmitry Torokhov" , "Mark Laws" Date: Mon, 14 Nov 2016 00:14:20 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 115/346] Input: i8042 - break load dependency between atkbd/psmouse and i8042 In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.39-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Dmitry Torokhov commit 4097461897df91041382ff6fcd2bfa7ee6b2448c upstream. As explained in 1407814240-4275-1-git-send-email-decui@microsoft.com we have a hard load dependency between i8042 and atkbd which prevents keyboard from working on Gen2 Hyper-V VMs. > hyperv_keyboard invokes serio_interrupt(), which needs a valid serio > driver like atkbd.c. atkbd.c depends on libps2.c because it invokes > ps2_command(). libps2.c depends on i8042.c because it invokes > i8042_check_port_owner(). As a result, hyperv_keyboard actually > depends on i8042.c. > > For a Generation 2 Hyper-V VM (meaning no i8042 device emulated), if a > Linux VM (like Arch Linux) happens to configure CONFIG_SERIO_I8042=m > rather than =y, atkbd.ko can't load because i8042.ko can't load(due to > no i8042 device emulated) and finally hyperv_keyboard can't work and > the user can't input: https://bugs.archlinux.org/task/39820 > (Ubuntu/RHEL/SUSE aren't affected since they use CONFIG_SERIO_I8042=y) To break the dependency we move away from using i8042_check_port_owner() and instead allow serio port owner specify a mutex that clients should use to serialize PS/2 command stream. Reported-by: Mark Laws Tested-by: Mark Laws Signed-off-by: Dmitry Torokhov Signed-off-by: Ben Hutchings --- drivers/input/serio/i8042.c | 16 +--------------- drivers/input/serio/libps2.c | 10 ++++------ include/linux/i8042.h | 6 ------ include/linux/serio.h | 24 +++++++++++++++++++----- 4 files changed, 24 insertions(+), 32 deletions(-) --- a/drivers/input/serio/i8042.c +++ b/drivers/input/serio/i8042.c @@ -1230,6 +1230,7 @@ static int __init i8042_create_kbd_port( serio->start = i8042_start; serio->stop = i8042_stop; serio->close = i8042_port_close; + serio->ps2_cmd_mutex = &i8042_mutex; serio->port_data = port; serio->dev.parent = &i8042_platform_device->dev; strlcpy(serio->name, "i8042 KBD port", sizeof(serio->name)); @@ -1321,21 +1322,6 @@ static void i8042_unregister_ports(void) } } -/* - * Checks whether port belongs to i8042 controller. - */ -bool i8042_check_port_owner(const struct serio *port) -{ - int i; - - for (i = 0; i < I8042_NUM_PORTS; i++) - if (i8042_ports[i].serio == port) - return true; - - return false; -} -EXPORT_SYMBOL(i8042_check_port_owner); - static void i8042_free_irqs(void) { if (i8042_aux_irq_registered) --- a/drivers/input/serio/libps2.c +++ b/drivers/input/serio/libps2.c @@ -56,19 +56,17 @@ EXPORT_SYMBOL(ps2_sendbyte); void ps2_begin_command(struct ps2dev *ps2dev) { - mutex_lock(&ps2dev->cmd_mutex); + struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex; - if (i8042_check_port_owner(ps2dev->serio)) - i8042_lock_chip(); + mutex_lock(m); } EXPORT_SYMBOL(ps2_begin_command); void ps2_end_command(struct ps2dev *ps2dev) { - if (i8042_check_port_owner(ps2dev->serio)) - i8042_unlock_chip(); + struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex; - mutex_unlock(&ps2dev->cmd_mutex); + mutex_unlock(m); } EXPORT_SYMBOL(ps2_end_command); --- a/include/linux/i8042.h +++ b/include/linux/i8042.h @@ -62,7 +62,6 @@ struct serio; void i8042_lock_chip(void); void i8042_unlock_chip(void); int i8042_command(unsigned char *param, int command); -bool i8042_check_port_owner(const struct serio *); int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str, struct serio *serio)); int i8042_remove_filter(bool (*filter)(unsigned char data, unsigned char str, @@ -83,11 +82,6 @@ static inline int i8042_command(unsigned return -ENODEV; } -static inline bool i8042_check_port_owner(const struct serio *serio) -{ - return false; -} - static inline int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str, struct serio *serio)) { --- a/include/linux/serio.h +++ b/include/linux/serio.h @@ -29,7 +29,8 @@ struct serio { struct serio_device_id id; - spinlock_t lock; /* protects critical sections from port's interrupt handler */ + /* Protects critical sections from port's interrupt handler */ + spinlock_t lock; int (*write)(struct serio *, unsigned char); int (*open)(struct serio *); @@ -38,16 +39,29 @@ struct serio { void (*stop)(struct serio *); struct serio *parent; - struct list_head child_node; /* Entry in parent->children list */ + /* Entry in parent->children list */ + struct list_head child_node; struct list_head children; - unsigned int depth; /* level of nesting in serio hierarchy */ + /* Level of nesting in serio hierarchy */ + unsigned int depth; - struct serio_driver *drv; /* accessed from interrupt, must be protected by serio->lock and serio->sem */ - struct mutex drv_mutex; /* protects serio->drv so attributes can pin driver */ + /* + * serio->drv is accessed from interrupt handlers; when modifying + * caller should acquire serio->drv_mutex and serio->lock. + */ + struct serio_driver *drv; + /* Protects serio->drv so attributes can pin current driver */ + struct mutex drv_mutex; struct device dev; struct list_head node; + + /* + * For use by PS/2 layer when several ports share hardware and + * may get indigestion when exposed to concurrent access (i8042). + */ + struct mutex *ps2_cmd_mutex; }; #define to_serio_port(d) container_of(d, struct serio, dev)