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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2016-07-25 21:36:54 +0300
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2016-07-28 00:20:09 +0300
commit4097461897df91041382ff6fcd2bfa7ee6b2448c (patch)
tree9bdfe6f3e9375ec8c23e7fd67ac8590c4f55939d /include/linux/serio.h
parent887ec0bfbd146c08e34ccb65a8f4251dc110e52f (diff)
downloadlinux-4097461897df91041382ff6fcd2bfa7ee6b2448c.tar.xz
Input: i8042 - break load dependency between atkbd/psmouse and i8042
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>
Diffstat (limited to 'include/linux/serio.h')
-rw-r--r--include/linux/serio.h24
1 files changed, 19 insertions, 5 deletions
diff --git a/include/linux/serio.h b/include/linux/serio.h
index df4ab5de1586..c733cff44e18 100644
--- a/include/linux/serio.h
+++ b/include/linux/serio.h
@@ -31,7 +31,8 @@ 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 *);
@@ -40,16 +41,29 @@ 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)