[PATCH v2 0/9] i2c: core: adapter registration fixes

[PATCH v2 0/9] i2c: core: adapter registration fixes

[Johan Hovold]

This series fixes a number of bugs related to adapter registration found
through inspection (when looking into addressing i2c lifetime issues).

Included are also two related cleanups.

Johan


Changes in v2
 - fix irq domain leak (new, flagged by Sashiko when reviewing v1)
 - add adapter to IDR before registration as needed by i2c-dev
 - honour devicetree alias also when using i2c_add_numbered_adapter()


Johan Hovold (9):
  i2c: core: fix irq domain leak on adapter registration failure
  i2c: core: fix hang on adapter registration failure
  i2c: core: fix adapter probe deferral loop
  i2c: core: fix adapter debugfs creation
  i2c: core: disable runtime PM on adapter registration failure
  i2c: core: fix adapter registration race
  i2c: core: fix adapter deregistration race
  i2c: core: clean up bus id allocation
  i2c: core: clean up adapter registration error label

 drivers/i2c/i2c-core-base.c | 165 ++++++++++++++++++++----------------
 1 file changed, 93 insertions(+), 72 deletions(-)

-- 
2.53.0

[PATCH v2 1/9] i2c: core: fix irq domain leak on adapter registration failure

[Johan Hovold]

Make sure to tear down the host notify irq domain on adapter
registration failure to avoid leaking it.

This issue was flagged by Sashiko when reviewing another adapter
registration fix.

Fixes: 4d5538f5882a ("i2c: use an IRQ to report Host Notify events, not alert")
Cc: stable@vger.kernel.org	# 4.10
Cc: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 9c46147e3506..abe8341c1d6e 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1574,7 +1574,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	if (res) {
 		pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
 		put_device(&adap->dev);
-		goto out_list;
+		goto err_remove_irq_domain;
 	}
 
 	adap->debugfs = debugfs_create_dir(dev_name(&adap->dev), i2c_debugfs_root);
@@ -1609,6 +1609,8 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	init_completion(&adap->dev_released);
 	device_unregister(&adap->dev);
 	wait_for_completion(&adap->dev_released);
+err_remove_irq_domain:
+	i2c_host_notify_irq_teardown(adap);
 out_list:
 	mutex_lock(&core_lock);
 	idr_remove(&i2c_adapter_idr, adap->nr);
-- 
2.53.0

[PATCH v2 2/9] i2c: core: fix hang on adapter registration failure

[Johan Hovold]

Clients may be registered from bus notifier callbacks when the adapter
is registered. On a subsequent error during registration, the adapter
references taken by such clients prevent the wait for the references to
be released from ever completing.

Fix this by refactoring client deregistration and deregistering also on
late adapter registration failures.

Fixes: f8756c67b3de ("i2c: core: call of_i2c_setup_smbus_alert in i2c_register_adapter")
Cc: stable@vger.kernel.org	# 4.15
Cc: Phil Reid <preid@electromag.com.au>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 49 ++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index abe8341c1d6e..e42851a10098 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -63,6 +63,7 @@
 static DEFINE_MUTEX(core_lock);
 static DEFINE_IDR(i2c_adapter_idr);
 
+static void i2c_deregister_clients(struct i2c_adapter *adap);
 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
 
 static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key);
@@ -1605,6 +1606,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	return 0;
 
 out_reg:
+	i2c_deregister_clients(adap);
 	debugfs_remove_recursive(adap->debugfs);
 	init_completion(&adap->dev_released);
 	device_unregister(&adap->dev);
@@ -1746,29 +1748,10 @@ static int __process_removed_adapter(struct device_driver *d, void *data)
 	return 0;
 }
 
-/**
- * i2c_del_adapter - unregister I2C adapter
- * @adap: the adapter being unregistered
- * Context: can sleep
- *
- * This unregisters an I2C adapter which was previously registered
- * by @i2c_add_adapter or @i2c_add_numbered_adapter.
- */
-void i2c_del_adapter(struct i2c_adapter *adap)
+static void i2c_deregister_clients(struct i2c_adapter *adap)
 {
-	struct i2c_adapter *found;
 	struct i2c_client *client, *next;
 
-	/* First make sure that this adapter was ever added */
-	mutex_lock(&core_lock);
-	found = idr_find(&i2c_adapter_idr, adap->nr);
-	mutex_unlock(&core_lock);
-	if (found != adap) {
-		pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
-		return;
-	}
-
-	i2c_acpi_remove_space_handler(adap);
 	/* Tell drivers about this removal */
 	mutex_lock(&core_lock);
 	bus_for_each_drv(&i2c_bus_type, NULL, adap,
@@ -1794,6 +1777,32 @@ void i2c_del_adapter(struct i2c_adapter *adap)
 	 * them up properly, so we give them a chance to do that first. */
 	device_for_each_child(&adap->dev, NULL, __unregister_client);
 	device_for_each_child(&adap->dev, NULL, __unregister_dummy);
+}
+
+/**
+ * i2c_del_adapter - unregister I2C adapter
+ * @adap: the adapter being unregistered
+ * Context: can sleep
+ *
+ * This unregisters an I2C adapter which was previously registered
+ * by @i2c_add_adapter or @i2c_add_numbered_adapter.
+ */
+void i2c_del_adapter(struct i2c_adapter *adap)
+{
+	struct i2c_adapter *found;
+
+	/* First make sure that this adapter was ever added */
+	mutex_lock(&core_lock);
+	found = idr_find(&i2c_adapter_idr, adap->nr);
+	mutex_unlock(&core_lock);
+	if (found != adap) {
+		pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
+		return;
+	}
+
+	i2c_acpi_remove_space_handler(adap);
+
+	i2c_deregister_clients(adap);
 
 	/* device name is gone after device_unregister */
 	dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
-- 
2.53.0

[PATCH v2 3/9] i2c: core: fix adapter probe deferral loop

[Johan Hovold]

Drivers must not probe defer after having registered devices as that
will trigger a probe loop if the devices bind to a driver (cf. commit
fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")).

Move the recovery initialisation, where the GPIO lookup may fail, before
registering the adapter to prevent this.

Fixes: 75820314de26 ("i2c: core: add generic I2C GPIO recovery")
Cc: stable@vger.kernel.org	# 5.9
Cc: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index e42851a10098..1caaa3b3ee10 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1562,6 +1562,10 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	adap->dev.type = &i2c_adapter_type;
 	device_initialize(&adap->dev);
 
+	res = i2c_init_recovery(adap);
+	if (res == -EPROBE_DEFER)
+		goto err_put_adap;
+
 	/*
 	 * This adapter can be used as a parent immediately after device_add(),
 	 * setup runtime-pm (especially ignore-children) before hand.
@@ -1574,8 +1578,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	res = device_add(&adap->dev);
 	if (res) {
 		pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
-		put_device(&adap->dev);
-		goto err_remove_irq_domain;
+		goto err_put_adap;
 	}
 
 	adap->debugfs = debugfs_create_dir(dev_name(&adap->dev), i2c_debugfs_root);
@@ -1584,10 +1587,6 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	if (res)
 		goto out_reg;
 
-	res = i2c_init_recovery(adap);
-	if (res == -EPROBE_DEFER)
-		goto out_reg;
-
 	dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
 
 	/* create pre-declared device nodes */
@@ -1608,10 +1607,12 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 out_reg:
 	i2c_deregister_clients(adap);
 	debugfs_remove_recursive(adap->debugfs);
+	device_del(&adap->dev);
+err_put_adap:
 	init_completion(&adap->dev_released);
-	device_unregister(&adap->dev);
+	put_device(&adap->dev);
 	wait_for_completion(&adap->dev_released);
-err_remove_irq_domain:
+
 	i2c_host_notify_irq_teardown(adap);
 out_list:
 	mutex_lock(&core_lock);
-- 
2.53.0

[PATCH v2 4/9] i2c: core: fix adapter debugfs creation

[Johan Hovold]

Clients can be registered from bus notifier callbacks so the debugfs
directory needs to be created before registering the adapter as clients
use that directory as their debugfs parent.

Move debugfs creation before adapter registration to avoid having
clients create their debugfs directories in the debugfs root (which is
also more likely to fail due to name collisions).

Fixes: 73febd775bdb ("i2c: create debugfs entry per adapter")
Cc: stable@vger.kernel.org	# 6.8
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 1caaa3b3ee10..8bf85aa2f0c2 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1575,14 +1575,14 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	pm_suspend_ignore_children(&adap->dev, true);
 	pm_runtime_enable(&adap->dev);
 
+	adap->debugfs = debugfs_create_dir(dev_name(&adap->dev), i2c_debugfs_root);
+
 	res = device_add(&adap->dev);
 	if (res) {
 		pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
-		goto err_put_adap;
+		goto err_remove_debugfs;
 	}
 
-	adap->debugfs = debugfs_create_dir(dev_name(&adap->dev), i2c_debugfs_root);
-
 	res = i2c_setup_smbus_alert(adap);
 	if (res)
 		goto out_reg;
@@ -1606,8 +1606,9 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 
 out_reg:
 	i2c_deregister_clients(adap);
-	debugfs_remove_recursive(adap->debugfs);
 	device_del(&adap->dev);
+err_remove_debugfs:
+	debugfs_remove_recursive(adap->debugfs);
 err_put_adap:
 	init_completion(&adap->dev_released);
 	put_device(&adap->dev);
-- 
2.53.0

[PATCH v2 5/9] i2c: core: disable runtime PM on adapter registration failure

[Johan Hovold]

Runtime PM is disabled by driver core when deregistering a device (and
on registration failure) but add an explicit disable to balance the
enable call when adapter registration fails for symmetry.

Fixes: 23a698fe65ec ("i2c: core: treat EPROBE_DEFER when acquiring SCL/SDA GPIOs")
Cc: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 8bf85aa2f0c2..20d48cb84a6c 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1609,6 +1609,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	device_del(&adap->dev);
 err_remove_debugfs:
 	debugfs_remove_recursive(adap->debugfs);
+	pm_runtime_disable(&adap->dev);
 err_put_adap:
 	init_completion(&adap->dev_released);
 	put_device(&adap->dev);
-- 
2.53.0

[PATCH v2 6/9] i2c: core: fix adapter registration race

[Johan Hovold]

Adapters can be looked up based on their id using i2c_get_adapter()
which takes a reference to the embedded struct device.

Make sure that the adapter (including its struct device) has been
initialised before adding it to the IDR to avoid accessing uninitialised
data which could, for example, lead to NULL-pointer dereferences or
use-after-free.

Note that the i2c-dev chardev, which is registered from a bus notifier,
currently uses i2c_get_adapter() so the adapter needs to be added to the
IDR before registration.

Fixes: 6e13e6418418 ("i2c: Add i2c_add_numbered_adapter()")
Cc: stable@vger.kernel.org	# 2.6.22
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 20d48cb84a6c..4863d660faf6 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1577,6 +1577,10 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 
 	adap->debugfs = debugfs_create_dir(dev_name(&adap->dev), i2c_debugfs_root);
 
+	mutex_lock(&core_lock);
+	idr_replace(&i2c_adapter_idr, adap, adap->nr);
+	mutex_unlock(&core_lock);
+
 	res = device_add(&adap->dev);
 	if (res) {
 		pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
@@ -1635,7 +1639,7 @@ static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
 	int id;
 
 	mutex_lock(&core_lock);
-	id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1, GFP_KERNEL);
+	id = idr_alloc(&i2c_adapter_idr, NULL, adap->nr, adap->nr + 1, GFP_KERNEL);
 	mutex_unlock(&core_lock);
 	if (WARN(id < 0, "couldn't get idr"))
 		return id == -ENOSPC ? -EBUSY : id;
@@ -1669,7 +1673,7 @@ int i2c_add_adapter(struct i2c_adapter *adapter)
 	}
 
 	mutex_lock(&core_lock);
-	id = idr_alloc(&i2c_adapter_idr, adapter,
+	id = idr_alloc(&i2c_adapter_idr, NULL,
 		       __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
 	mutex_unlock(&core_lock);
 	if (WARN(id < 0, "couldn't get idr"))
-- 
2.53.0

[PATCH v2 7/9] i2c: core: fix adapter deregistration race

[Johan Hovold]

Adapters can be looked up by their id using i2c_get_adapter() which
takes a reference to the embedded struct device.

Remove the adapter from the IDR before tearing it down during
deregistration to make sure its resources are not accessed after having
been freed (e.g.the device name).

Fixes: 35fc37f81881 ("i2c: Limit core locking to the necessary sections")
Cc: stable@vger.kernel.org	# 2.6.31
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 4863d660faf6..f72f15a1b067 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1801,6 +1801,8 @@ void i2c_del_adapter(struct i2c_adapter *adap)
 	/* First make sure that this adapter was ever added */
 	mutex_lock(&core_lock);
 	found = idr_find(&i2c_adapter_idr, adap->nr);
+	if (found == adap)
+		idr_replace(&i2c_adapter_idr, NULL, adap->nr);
 	mutex_unlock(&core_lock);
 	if (found != adap) {
 		pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
-- 
2.53.0

[PATCH v2 8/9] i2c: core: clean up bus id allocation

[Johan Hovold]

Clean up bus id allocation by using a common helper and deferring it
until it is needed during adapter registration.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 85 +++++++++++++++++++------------------
 1 file changed, 43 insertions(+), 42 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index f72f15a1b067..5350ee54132b 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1517,23 +1517,48 @@ int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
 }
 EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify);
 
+static int i2c_allocate_adapter_id(struct i2c_adapter *adap)
+{
+	int id, start, end;
+
+	if (adap->nr == -1) {
+		start = __i2c_first_dynamic_bus_num;
+		end = 0;
+	} else {
+		start = adap->nr;
+		end = adap->nr + 1;
+	}
+
+	mutex_lock(&core_lock);
+	id = idr_alloc(&i2c_adapter_idr, NULL, start, end, GFP_KERNEL);
+	mutex_unlock(&core_lock);
+	if (id < 0) {
+		if (adap->nr != -1 && id == -ENOSPC)
+			id = -EBUSY;
+		pr_err("adapter '%s': failed to allocate id: %d\n", adap->name, id);
+		return id;
+	}
+
+	adap->nr = id;
+
+	return 0;
+}
+
 static int i2c_register_adapter(struct i2c_adapter *adap)
 {
-	int res = -EINVAL;
+	int res;
 
 	/* Can't register until after driver model init */
-	if (WARN_ON(!is_registered)) {
-		res = -EAGAIN;
-		goto out_list;
-	}
+	if (WARN_ON(!is_registered))
+		return -EAGAIN;
 
 	/* Sanity checks */
 	if (WARN(!adap->name[0], "i2c adapter has no name"))
-		goto out_list;
+		return -EINVAL;
 
 	if (!adap->algo) {
 		pr_err("adapter '%s': no algo supplied!\n", adap->name);
-		goto out_list;
+		return -EINVAL;
 	}
 
 	if (!adap->lock_ops)
@@ -1554,9 +1579,13 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	if (res) {
 		pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n",
 		       adap->name, res);
-		goto out_list;
+		return res;
 	}
 
+	res = i2c_allocate_adapter_id(adap);
+	if (res)
+		goto err_remove_irq_domain;
+
 	dev_set_name(&adap->dev, "i2c-%d", adap->nr);
 	adap->dev.bus = &i2c_bus_type;
 	adap->dev.type = &i2c_adapter_type;
@@ -1619,32 +1648,13 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	put_device(&adap->dev);
 	wait_for_completion(&adap->dev_released);
 
-	i2c_host_notify_irq_teardown(adap);
-out_list:
 	mutex_lock(&core_lock);
 	idr_remove(&i2c_adapter_idr, adap->nr);
 	mutex_unlock(&core_lock);
-	return res;
-}
-
-/**
- * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
- * @adap: the adapter to register (with adap->nr initialized)
- * Context: can sleep
- *
- * See i2c_add_numbered_adapter() for details.
- */
-static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
-{
-	int id;
-
-	mutex_lock(&core_lock);
-	id = idr_alloc(&i2c_adapter_idr, NULL, adap->nr, adap->nr + 1, GFP_KERNEL);
-	mutex_unlock(&core_lock);
-	if (WARN(id < 0, "couldn't get idr"))
-		return id == -ENOSPC ? -EBUSY : id;
+err_remove_irq_domain:
+	i2c_host_notify_irq_teardown(adap);
 
-	return i2c_register_adapter(adap);
+	return res;
 }
 
 /**
@@ -1667,17 +1677,8 @@ int i2c_add_adapter(struct i2c_adapter *adapter)
 	int id;
 
 	id = of_alias_get_id(dev->of_node, "i2c");
-	if (id >= 0) {
-		adapter->nr = id;
-		return __i2c_add_numbered_adapter(adapter);
-	}
-
-	mutex_lock(&core_lock);
-	id = idr_alloc(&i2c_adapter_idr, NULL,
-		       __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
-	mutex_unlock(&core_lock);
-	if (WARN(id < 0, "couldn't get idr"))
-		return id;
+	if (id < 0)
+		id = -1;
 
 	adapter->nr = id;
 
@@ -1713,7 +1714,7 @@ int i2c_add_numbered_adapter(struct i2c_adapter *adap)
 	if (adap->nr == -1) /* -1 means dynamically assign bus id */
 		return i2c_add_adapter(adap);
 
-	return __i2c_add_numbered_adapter(adap);
+	return i2c_register_adapter(adap);
 }
 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
 
-- 
2.53.0

[PATCH v2 9/9] i2c: core: clean up adapter registration error label

[Johan Hovold]

Clean up the adapter registration error labels by making sure that also
the last one is named after what it does.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 5350ee54132b..029ebe44c68e 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1618,7 +1618,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 
 	res = i2c_setup_smbus_alert(adap);
 	if (res)
-		goto out_reg;
+		goto err_deregister_clients;
 
 	dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
 
@@ -1637,7 +1637,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 
 	return 0;
 
-out_reg:
+err_deregister_clients:
 	i2c_deregister_clients(adap);
 	device_del(&adap->dev);
 err_remove_debugfs:
-- 
2.53.0