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Subject[2.6 RFC/PATCH] Input: possible deadlock in i8042
Date
If request_irq fails in i8042_open it will call serio_unregister_port,
which takes serio_sem. i8042_open may be called:

serio_register_port - serio_find_dev - dev->connect
serio_register_device - dev->connect

Both serio_register_port and serio_register_device take serio_sem as well.

I think that serio_{register|unregister}_port can be converted into
submitting requests to kseriod thus removing deadlock on the serio_sem.

The patch below is on top of serio* patches in Andrew Morton's -mm tree.

Dmitry

===================================================================


ChangeSet@1.1512, 2003-11-30 02:42:54-05:00, dtor_core@ameritech.net
Input: Use kseriod to register/unregister serio ports


serio.c | 22 ++++++++++++++--------
1 files changed, 14 insertions(+), 8 deletions(-)

===================================================================

diff -Nru a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
--- a/drivers/input/serio/serio.c Sun Nov 30 03:01:40 2003
+++ b/drivers/input/serio/serio.c Sun Nov 30 03:01:40 2003
@@ -83,8 +83,10 @@
}
}

-#define SERIO_RESCAN 1
-#define SERIO_RECONNECT 2
+#define SERIO_RESCAN 1
+#define SERIO_RECONNECT 2
+#define SERIO_REGISTER_PORT 3
+#define SERIO_UNREGISTER_PORT 4

static DECLARE_WAIT_QUEUE_HEAD(serio_wait);
static DECLARE_COMPLETION(serio_exited);
@@ -111,6 +113,14 @@
goto event_done;

switch (event->type) {
+ case SERIO_REGISTER_PORT :
+ __serio_register_port(event->serio);
+ break;
+
+ case SERIO_UNREGISTER_PORT :
+ __serio_unregister_port(event->serio);
+ break;
+
case SERIO_RECONNECT :
if (event->serio->dev && event->serio->dev->reconnect)
if (event->serio->dev->reconnect(event->serio) == 0)
@@ -192,9 +202,7 @@

void serio_register_port(struct serio *serio)
{
- down(&serio_sem);
- __serio_register_port(serio);
- up(&serio_sem);
+ serio_queue_event(serio, SERIO_REGISTER_PORT);
}

/*
@@ -210,9 +218,7 @@

void serio_unregister_port(struct serio *serio)
{
- down(&serio_sem);
- __serio_unregister_port(serio);
- up(&serio_sem);
+ serio_queue_event(serio, SERIO_UNREGISTER_PORT);
}

/*
-
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