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authorEric W. Biederman <ebiederm@xmission.com>2010-01-05 17:56:02 -0800
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2010-01-06 00:14:32 -0800
commit59b015133cd0034f5904a76969d73476380aac46 (patch)
tree578643cc919b7e62b5086718d5c3f9b0fee836a9 /drivers/input/keyboard
parentabf2a117c67a67fbb611913a31109d0ff66ab073 (diff)
Input: serio - fix potential deadlock when unbinding drivers
sysfs_remove_group() waits for sysfs attributes to be removed, therefore we do not need to worry about driver-specific attributes being accessed after driver has been detached from the device. In fact, attempts to take serio->drv_mutex in attribute methods may lead to the following deadlock: sysfs_read_file() fill_read_buffer() sysfs_get_active_two() psmouse_attr_show_helper() serio_pin_driver() serio_disconnect_driver() mutex_lock(&serio->drv_mutex); <--------> mutex_lock(&serio_drv_mutex); psmouse_disconnect() sysfs_remove_group(... psmouse_attr_group); .... sysfs_deactivate(); wait_for_completion(); Fix this by removing calls to serio_[un]pin_driver() and functions themselves and using driver-private mutexes to serialize access to attribute's set() methods that may change device state. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Diffstat (limited to 'drivers/input/keyboard')
-rw-r--r--drivers/input/keyboard/atkbd.c59
1 files changed, 25 insertions, 34 deletions
diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c
index 1f5e2ce327d..1cf32a7814d 100644
--- a/drivers/input/keyboard/atkbd.c
+++ b/drivers/input/keyboard/atkbd.c
@@ -225,8 +225,10 @@ struct atkbd {
struct delayed_work event_work;
unsigned long event_jiffies;
- struct mutex event_mutex;
unsigned long event_mask;
+
+ /* Serializes reconnect(), attr->set() and event work */
+ struct mutex mutex;
};
/*
@@ -577,7 +579,7 @@ static void atkbd_event_work(struct work_struct *work)
{
struct atkbd *atkbd = container_of(work, struct atkbd, event_work.work);
- mutex_lock(&atkbd->event_mutex);
+ mutex_lock(&atkbd->mutex);
if (!atkbd->enabled) {
/*
@@ -596,7 +598,7 @@ static void atkbd_event_work(struct work_struct *work)
atkbd_set_repeat_rate(atkbd);
}
- mutex_unlock(&atkbd->event_mutex);
+ mutex_unlock(&atkbd->mutex);
}
/*
@@ -612,7 +614,7 @@ static void atkbd_schedule_event_work(struct atkbd *atkbd, int event_bit)
atkbd->event_jiffies = jiffies;
set_bit(event_bit, &atkbd->event_mask);
- wmb();
+ mb();
schedule_delayed_work(&atkbd->event_work, delay);
}
@@ -849,12 +851,13 @@ static void atkbd_disconnect(struct serio *serio)
{
struct atkbd *atkbd = serio_get_drvdata(serio);
+ sysfs_remove_group(&serio->dev.kobj, &atkbd_attribute_group);
+
atkbd_disable(atkbd);
/* make sure we don't have a command in flight */
cancel_delayed_work_sync(&atkbd->event_work);
- sysfs_remove_group(&serio->dev.kobj, &atkbd_attribute_group);
input_unregister_device(atkbd->dev);
serio_close(serio);
serio_set_drvdata(serio, NULL);
@@ -1087,7 +1090,7 @@ static int atkbd_connect(struct serio *serio, struct serio_driver *drv)
atkbd->dev = dev;
ps2_init(&atkbd->ps2dev, serio);
INIT_DELAYED_WORK(&atkbd->event_work, atkbd_event_work);
- mutex_init(&atkbd->event_mutex);
+ mutex_init(&atkbd->mutex);
switch (serio->id.type) {
@@ -1160,19 +1163,23 @@ static int atkbd_reconnect(struct serio *serio)
{
struct atkbd *atkbd = serio_get_drvdata(serio);
struct serio_driver *drv = serio->drv;
+ int retval = -1;
if (!atkbd || !drv) {
printk(KERN_DEBUG "atkbd: reconnect request, but serio is disconnected, ignoring...\n");
return -1;
}
+ mutex_lock(&atkbd->mutex);
+
atkbd_disable(atkbd);
if (atkbd->write) {
if (atkbd_probe(atkbd))
- return -1;
+ goto out;
+
if (atkbd->set != atkbd_select_set(atkbd, atkbd->set, atkbd->extra))
- return -1;
+ goto out;
atkbd_activate(atkbd);
@@ -1190,8 +1197,11 @@ static int atkbd_reconnect(struct serio *serio)
}
atkbd_enable(atkbd);
+ retval = 0;
- return 0;
+ out:
+ mutex_unlock(&atkbd->mutex);
+ return retval;
}
static struct serio_device_id atkbd_serio_ids[] = {
@@ -1235,47 +1245,28 @@ static ssize_t atkbd_attr_show_helper(struct device *dev, char *buf,
ssize_t (*handler)(struct atkbd *, char *))
{
struct serio *serio = to_serio_port(dev);
- int retval;
-
- retval = serio_pin_driver(serio);
- if (retval)
- return retval;
-
- if (serio->drv != &atkbd_drv) {
- retval = -ENODEV;
- goto out;
- }
-
- retval = handler((struct atkbd *)serio_get_drvdata(serio), buf);
+ struct atkbd *atkbd = serio_get_drvdata(serio);
-out:
- serio_unpin_driver(serio);
- return retval;
+ return handler(atkbd, buf);
}
static ssize_t atkbd_attr_set_helper(struct device *dev, const char *buf, size_t count,
ssize_t (*handler)(struct atkbd *, const char *, size_t))
{
struct serio *serio = to_serio_port(dev);
- struct atkbd *atkbd;
+ struct atkbd *atkbd = serio_get_drvdata(serio);
int retval;
- retval = serio_pin_driver(serio);
+ retval = mutex_lock_interruptible(&atkbd->mutex);
if (retval)
return retval;
- if (serio->drv != &atkbd_drv) {
- retval = -ENODEV;
- goto out;
- }
-
- atkbd = serio_get_drvdata(serio);
atkbd_disable(atkbd);
retval = handler(atkbd, buf, count);
atkbd_enable(atkbd);
-out:
- serio_unpin_driver(serio);
+ mutex_unlock(&atkbd->mutex);
+
return retval;
}