releases/4.7.3/input-i8042-break-load-dependency-between-atkbd-psmouse-and-i8042.patch

   1 From 4097461897df91041382ff6fcd2bfa7ee6b2448c Mon Sep 17 00:00:00 2001
   2 From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
   3 Date: Mon, 25 Jul 2016 11:36:54 -0700
   4 Subject: Input: i8042 - break load dependency between atkbd/psmouse and i8042
   5
   6 From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
   7
   8 commit 4097461897df91041382ff6fcd2bfa7ee6b2448c upstream.
   9
  10 As explained in 1407814240-4275-1-git-send-email-decui@microsoft.com we
  11 have a hard load dependency between i8042 and atkbd which prevents
  12 keyboard from working on Gen2 Hyper-V VMs.
  13
  14 > hyperv_keyboard invokes serio_interrupt(), which needs a valid serio
  15 > driver like atkbd.c.  atkbd.c depends on libps2.c because it invokes
  16 > ps2_command().  libps2.c depends on i8042.c because it invokes
  17 > i8042_check_port_owner().  As a result, hyperv_keyboard actually
  18 > depends on i8042.c.
  19 >
  20 > For a Generation 2 Hyper-V VM (meaning no i8042 device emulated), if a
  21 > Linux VM (like Arch Linux) happens to configure CONFIG_SERIO_I8042=m
  22 > rather than =y, atkbd.ko can't load because i8042.ko can't load(due to
  23 > no i8042 device emulated) and finally hyperv_keyboard can't work and
  24 > the user can't input: https://bugs.archlinux.org/task/39820
  25 > (Ubuntu/RHEL/SUSE aren't affected since they use CONFIG_SERIO_I8042=y)
  26
  27 To break the dependency we move away from using i8042_check_port_owner()
  28 and instead allow serio port owner specify a mutex that clients should use
  29 to serialize PS/2 command stream.
  30
  31 Reported-by: Mark Laws <mdl@60hz.org>
  32 Tested-by: Mark Laws <mdl@60hz.org>
  33 Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
  34 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  35
  36 ---
  37  drivers/input/serio/i8042.c  |   16 +---------------
  38  drivers/input/serio/libps2.c |   10 ++++------
  39  include/linux/i8042.h        |    6 ------
  40  include/linux/serio.h        |   24 +++++++++++++++++++-----
  41  4 files changed, 24 insertions(+), 32 deletions(-)
  42
  43 --- a/drivers/input/serio/i8042.c
  44 +++ b/drivers/input/serio/i8042.c
  45 @@ -1277,6 +1277,7 @@ static int __init i8042_create_kbd_port(
  46         serio->start            = i8042_start;
  47         serio->stop             = i8042_stop;
  48         serio->close            = i8042_port_close;
  49 +       serio->ps2_cmd_mutex    = &i8042_mutex;
  50         serio->port_data        = port;
  51         serio->dev.parent       = &i8042_platform_device->dev;
  52         strlcpy(serio->name, "i8042 KBD port", sizeof(serio->name));
  53 @@ -1373,21 +1374,6 @@ static void i8042_unregister_ports(void)
  54         }
  55  }
  56
  57 -/*
  58 - * Checks whether port belongs to i8042 controller.
  59 - */
  60 -bool i8042_check_port_owner(const struct serio *port)
  61 -{
  62 -       int i;
  63 -
  64 -       for (i = 0; i < I8042_NUM_PORTS; i++)
  65 -               if (i8042_ports[i].serio == port)
  66 -                       return true;
  67 -
  68 -       return false;
  69 -}
  70 -EXPORT_SYMBOL(i8042_check_port_owner);
  71 -
  72  static void i8042_free_irqs(void)
  73  {
  74         if (i8042_aux_irq_registered)
  75 --- a/drivers/input/serio/libps2.c
  76 +++ b/drivers/input/serio/libps2.c
  77 @@ -56,19 +56,17 @@ EXPORT_SYMBOL(ps2_sendbyte);
  78
  79  void ps2_begin_command(struct ps2dev *ps2dev)
  80  {
  81 -       mutex_lock(&ps2dev->cmd_mutex);
  82 +       struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
  83
  84 -       if (i8042_check_port_owner(ps2dev->serio))
  85 -               i8042_lock_chip();
  86 +       mutex_lock(m);
  87  }
  88  EXPORT_SYMBOL(ps2_begin_command);
  89
  90  void ps2_end_command(struct ps2dev *ps2dev)
  91  {
  92 -       if (i8042_check_port_owner(ps2dev->serio))
  93 -               i8042_unlock_chip();
  94 +       struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
  95
  96 -       mutex_unlock(&ps2dev->cmd_mutex);
  97 +       mutex_unlock(m);
  98  }
  99  EXPORT_SYMBOL(ps2_end_command);
 100
 101 --- a/include/linux/i8042.h
 102 +++ b/include/linux/i8042.h
 103 @@ -62,7 +62,6 @@ struct serio;
 104  void i8042_lock_chip(void);
 105  void i8042_unlock_chip(void);
 106  int i8042_command(unsigned char *param, int command);
 107 -bool i8042_check_port_owner(const struct serio *);
 108  int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
 109                                         struct serio *serio));
 110  int i8042_remove_filter(bool (*filter)(unsigned char data, unsigned char str,
 111 @@ -83,11 +82,6 @@ static inline int i8042_command(unsigned
 112         return -ENODEV;
 113  }
 114
 115 -static inline bool i8042_check_port_owner(const struct serio *serio)
 116 -{
 117 -       return false;
 118 -}
 119 -
 120  static inline int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
 121                                         struct serio *serio))
 122  {
 123 --- a/include/linux/serio.h
 124 +++ b/include/linux/serio.h
 125 @@ -31,7 +31,8 @@ struct serio {
 126
 127         struct serio_device_id id;
 128
 129 -       spinlock_t lock;                /* protects critical sections from port's interrupt handler */
 130 +       /* Protects critical sections from port's interrupt handler */
 131 +       spinlock_t lock;
 132
 133         int (*write)(struct serio *, unsigned char);
 134         int (*open)(struct serio *);
 135 @@ -40,16 +41,29 @@ struct serio {
 136         void (*stop)(struct serio *);
 137
 138         struct serio *parent;
 139 -       struct list_head child_node;    /* Entry in parent->children list */
 140 +       /* Entry in parent->children list */
 141 +       struct list_head child_node;
 142         struct list_head children;
 143 -       unsigned int depth;             /* level of nesting in serio hierarchy */
 144 +       /* Level of nesting in serio hierarchy */
 145 +       unsigned int depth;
 146
 147 -       struct serio_driver *drv;       /* accessed from interrupt, must be protected by serio->lock and serio->sem */
 148 -       struct mutex drv_mutex;         /* protects serio->drv so attributes can pin driver */
 149 +       /*
 150 +        * serio->drv is accessed from interrupt handlers; when modifying
 151 +        * caller should acquire serio->drv_mutex and serio->lock.
 152 +        */
 153 +       struct serio_driver *drv;
 154 +       /* Protects serio->drv so attributes can pin current driver */
 155 +       struct mutex drv_mutex;
 156
 157         struct device dev;
 158
 159         struct list_head node;
 160 +
 161 +       /*
 162 +        * For use by PS/2 layer when several ports share hardware and
 163 +        * may get indigestion when exposed to concurrent access (i8042).
 164 +        */
 165 +       struct mutex *ps2_cmd_mutex;
 166  };
 167  #define to_serio_port(d)       container_of(d, struct serio, dev)
 168