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authorDavid Fries <david@fries.net>2014-04-16 01:21:21 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-04-16 14:07:51 -0700
commit18d7f891bcc7e49f2900215f17a861ccec34b138 (patch)
treeb70c5385376b8463fc4d1850574d7c7d8be9e4b1
parent593ceb0c7046c640cf463022189428a45219f595 (diff)
downloadlinux-linaro-stable-18d7f891bcc7e49f2900215f17a861ccec34b138.tar.gz
w1: avoid recursive device_add
__w1_attach_slave_device calls device_add which calls w1_bus_notify which calls the w1_bq27000 slave driver, which calls platform_device_add and device_add and deadlocks on getting &(&priv->bus_notifier)->rwsem as it is still held in the previous device_add. This avoids the problem by processing the family add/remove outside of the slave device_add call. Commit 47eba33a0997fc7362a introduced this deadlock and added a KOBJ_ADD, as the add was already reported in device_register two add events were being sent. This change suppresses the device_register add so that any slave device sysfs entries are setup before the add goes out. Belisko Marek reported this change fixed the deadlock he was seeing on ARM device tree, while testing on my x86-64 system never saw the deadlock. Reported-by: Belisko Marek <marek.belisko@gmail.com> Signed-off-by: David Fries <David@Fries.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/w1/w1.c32
1 files changed, 6 insertions, 26 deletions
diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index b96f61b15dc6..ff52618cafbe 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -614,27 +614,11 @@ end:
return err;
}
-/*
- * Handle sysfs file creation and removal here, before userspace is told that
- * the device is added / removed from the system
- */
-static int w1_bus_notify(struct notifier_block *nb, unsigned long action,
- void *data)
+static int w1_family_notify(unsigned long action, struct w1_slave *sl)
{
- struct device *dev = data;
- struct w1_slave *sl;
struct w1_family_ops *fops;
int err;
- /*
- * Only care about slave devices at the moment. Yes, we should use a
- * separate "type" for this, but for now, look at the release function
- * to know which type it is...
- */
- if (dev->release != w1_slave_release)
- return 0;
-
- sl = dev_to_w1_slave(dev);
fops = sl->family->fops;
if (!fops)
@@ -673,10 +657,6 @@ static int w1_bus_notify(struct notifier_block *nb, unsigned long action,
return 0;
}
-static struct notifier_block w1_bus_nb = {
- .notifier_call = w1_bus_notify,
-};
-
static int __w1_attach_slave_device(struct w1_slave *sl)
{
int err;
@@ -698,6 +678,9 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__,
dev_name(&sl->dev), sl);
+ /* suppress for w1_family_notify before sending KOBJ_ADD */
+ dev_set_uevent_suppress(&sl->dev, true);
+
err = device_register(&sl->dev);
if (err < 0) {
dev_err(&sl->dev,
@@ -705,7 +688,7 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
dev_name(&sl->dev), err);
return err;
}
-
+ w1_family_notify(BUS_NOTIFY_ADD_DEVICE, sl);
dev_set_uevent_suppress(&sl->dev, false);
kobject_uevent(&sl->dev.kobj, KOBJ_ADD);
@@ -799,6 +782,7 @@ int w1_unref_slave(struct w1_slave *sl)
msg.type = W1_SLAVE_REMOVE;
w1_netlink_send(sl->master, &msg);
+ w1_family_notify(BUS_NOTIFY_DEL_DEVICE, sl);
device_unregister(&sl->dev);
#ifdef DEBUG
memset(sl, 0, sizeof(*sl));
@@ -1186,10 +1170,6 @@ static int __init w1_init(void)
goto err_out_exit_init;
}
- retval = bus_register_notifier(&w1_bus_type, &w1_bus_nb);
- if (retval)
- goto err_out_bus_unregister;
-
retval = driver_register(&w1_master_driver);
if (retval) {
printk(KERN_ERR