On Thu, Aug 18, 2016 at 6:59 AM, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > 4.7-stable review patch. If anyone has any objections, please let me know. Greg, please hold this patch off till your next cycle. I will be sending a fixup for it to Linus today or tomorrow. Thanks! > > ------------------ > > From: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> > > commit 4097461897df91041382ff6fcd2bfa7ee6b2448c upstream. > > As explained in 1407814240-4275-1-git-send-email-decui@xxxxxxxxxxxxx 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@xxxxxxxx> > Tested-by: Mark Laws <mdl@xxxxxxxx> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > --- > 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 > @@ -1277,6 +1277,7 @@ 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)); > @@ -1373,21 +1374,6 @@ 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 > @@ -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) > > > -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html