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Date: Wed, 21 Aug 2013 13:24:32 -0700
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Evgeniy Polyakov <zbr@...emap.net>
Subject: [PATCH 1/2] w1: remove race with sysfs file creation
W1 slave sysfs files are created _after_ userspace is notified that the
device has been added to the system. Fix that race by moving the
creation/remove of the files to the bus notifier that is there for doing
this type of thing.
Cc: Evgeniy Polyakov <zbr@...emap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/w1/w1.c | 111 +++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 73 insertions(+), 38 deletions(-)
diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 0459df84..3c798db0 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -587,6 +587,73 @@ 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)
+{
+ struct device *dev = data;
+ struct w1_slave *sl;
+ 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);
+
+ switch (action) {
+ case BUS_NOTIFY_ADD_DEVICE:
+ /* Create our sysfs files before userspace is told about it */
+ /* Create "name" entry */
+ err = device_create_file(&sl->dev, &w1_slave_attr_name);
+ if (err < 0) {
+ dev_err(&sl->dev,
+ "sysfs file creation for [%s] failed. err=%d\n",
+ dev_name(&sl->dev), err);
+ return err;
+ }
+
+ /* Create "id" entry */
+ err = device_create_file(&sl->dev, &w1_slave_attr_id);
+ if (err < 0) {
+ dev_err(&sl->dev,
+ "sysfs file creation for [%s] failed. err=%d\n",
+ dev_name(&sl->dev), err);
+ return err;
+ }
+
+ /* if the family driver needs to initialize something... */
+ if (sl->family->fops && sl->family->fops->add_slave &&
+ ((err = sl->family->fops->add_slave(sl)) < 0)) {
+ dev_err(&sl->dev,
+ "sysfs file creation for [%s] failed. err=%d\n",
+ dev_name(&sl->dev), err);
+ return err;
+ }
+
+ break;
+ case BUS_NOTIFY_DEL_DEVICE:
+ /* Remove our sysfs files */
+ if (sl->family->fops && sl->family->fops->remove_slave)
+ sl->family->fops->remove_slave(sl);
+ device_remove_file(&sl->dev, &w1_slave_attr_id);
+ device_remove_file(&sl->dev, &w1_slave_attr_name);
+ break;
+ }
+ 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;
@@ -615,44 +682,13 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
return err;
}
- /* Create "name" entry */
- err = device_create_file(&sl->dev, &w1_slave_attr_name);
- if (err < 0) {
- dev_err(&sl->dev,
- "sysfs file creation for [%s] failed. err=%d\n",
- dev_name(&sl->dev), err);
- goto out_unreg;
- }
-
- /* Create "id" entry */
- err = device_create_file(&sl->dev, &w1_slave_attr_id);
- if (err < 0) {
- dev_err(&sl->dev,
- "sysfs file creation for [%s] failed. err=%d\n",
- dev_name(&sl->dev), err);
- goto out_rem1;
- }
- /* if the family driver needs to initialize something... */
- if (sl->family->fops && sl->family->fops->add_slave &&
- ((err = sl->family->fops->add_slave(sl)) < 0)) {
- dev_err(&sl->dev,
- "sysfs file creation for [%s] failed. err=%d\n",
- dev_name(&sl->dev), err);
- goto out_rem2;
- }
+ dev_set_uevent_suppress(&sl->dev, false);
+ kobject_uevent(&sl->dev.kobj, KOBJ_ADD);
list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
return 0;
-
-out_rem2:
- device_remove_file(&sl->dev, &w1_slave_attr_id);
-out_rem1:
- device_remove_file(&sl->dev, &w1_slave_attr_name);
-out_unreg:
- device_unregister(&sl->dev);
- return err;
}
static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
@@ -723,16 +759,11 @@ void w1_slave_detach(struct w1_slave *sl)
list_del(&sl->w1_slave_entry);
- if (sl->family->fops && sl->family->fops->remove_slave)
- sl->family->fops->remove_slave(sl);
-
memset(&msg, 0, sizeof(msg));
memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
msg.type = W1_SLAVE_REMOVE;
w1_netlink_send(sl->master, &msg);
- device_remove_file(&sl->dev, &w1_slave_attr_id);
- device_remove_file(&sl->dev, &w1_slave_attr_name);
device_unregister(&sl->dev);
wait_for_completion(&sl->released);
@@ -1017,6 +1048,10 @@ 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
--
1.8.3.rc0.20.gb99dd2e
--
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