[ resending to inlude the list ] Hi Mark, On Tue, Jul 19, 2016 at 06:22:57PM -0700, Mark Laws wrote: > On Tue, Jul 19, 2016 at 4:34 PM, KY Srinivasan <kys@xxxxxxxxxxxxx> wrote: > >> -----Original Message----- > >> From: Mark Laws [mailto:mdl@xxxxxxxx] > >> Sent: Tuesday, July 19, 2016 1:29 AM > >> To: Van De Ven, Arjan <arjan.van.de.ven@xxxxxxxxx> > >> Cc: KY Srinivasan <kys@xxxxxxxxxxxxx> > >> Subject: Re: [PATCH] Input: i8042 - Fix console keyboard support on Gen2 > >> Hyper-V VMs > >> > >> On Tue, Jun 21, 2016 at 7:41 PM, Mark Laws <mdl@xxxxxxxx> wrote: > >> > On Wed, Jun 22, 2016 at 11:36 AM, Van De Ven, Arjan > >> > <arjan.van.de.ven@xxxxxxxxx> wrote: > >> >>> Hi KY and Arjan, > >> >>> > >> >>> Does anything remain to be fixed in this patch? > >> >> > >> >> it works great for me.... 8042 is no longer on my radar of trouble makers... > >> > > >> > Glad to hear it. I hope it can get merged soon, as it's surely been a > >> > nuisance for at least a few other folks. > >> > >> Hi, > >> > >> Is there anyone I should ping about getting this merged? Should I CC > >> Dmitry again? > > > > Please do. > > > > K. Y > > Hi Dmitry, > > Could you please take a look at the patch earlier in this thread and > merge it if it's OK? K.Y. and Arjan have said it's good. I can provide > a rebased version if needed, though I think the one from this thread > should apply cleanly. Sorry for the delay, the reason is that I absolutely hated exporting the ports array from i8042 and into yet another module. Even though I was the author of i8042_check_port_owner() I do not like this mechanism at all and I think it is worse than doing a small layer violation and having a shared PS/2 mutex directly in serio port structure. Can you please tell me if the patch below solves the issue for you? Thanks! -- Dmitry Input: i8042 - break load dependency between atkbd/psmouse and i8042 From: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> 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> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> --- 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(-) diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c index 4541957..b4d3408 100644 --- a/drivers/input/serio/i8042.c +++ b/drivers/input/serio/i8042.c @@ -1277,6 +1277,7 @@ static int __init i8042_create_kbd_port(void) 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) diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c index 316f2c8..83e9c66 100644 --- 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); diff --git a/include/linux/i8042.h b/include/linux/i8042.h index 0f9bafa..d98780c 100644 --- 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 char *param, int command) 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)) { diff --git a/include/linux/serio.h b/include/linux/serio.h index df4ab5d..c733cff 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) -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
