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Input: i8042 - break load dependency between atkbd/psmouse and i8042

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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 <mdl@60hz.org>
Tested-by: Mark Laws <mdl@60hz.org>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Dmitry Torokhov
2016-07-25 11:36:54 -07:00
parent 887ec0bfbd
commit 4097461897
4 changed files with 24 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/input/serio/libps2.c
+4 -6
View File
@@ -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);