Re: Regression caused by "eeprom: at24: Probe for DDR3 thermal sensor in the SPD case" - "sysfs: cannot create duplicate filename"

[Heiner Kallweit <hkallweit1@gmail.com>]

On 23.07.2024 16:12, Krzysztof Olędzki wrote:
> On 06.07.2024 at 18:42, Krzysztof Olędzki wrote:
>> On 02.07.2024 at 13:25, Heiner Kallweit wrote:
>>> On 23.06.2024 20:47, Krzysztof Olędzki wrote:
>>>> Hi,
>>>>
>>>> After upgrading kernel to Linux 6.6.34 on one of my systems, I noticed "sysfs: cannot create duplicate filename" and i2c registration errors in dmesg, please see below.
>>>>
>>>> This seems to be related to https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-6.6.y&id=4d5ace787273cb159bfdcf1c523df957938b3e42 - reverting the change fixes the problem.
>>
>> <CUT>
>>
>>>
>>> Could you please test whether the attached two experimental patches fix the issue for you?
>>> They serialize client device instantiation per I2C adapter, and include the client device
>>> name in the check whether a bus address is busy.
>>
>> Sadly, they crash the kernel.
>>
>> I will get serial console attached there next week, so will be able to capture the full crash.
>> For now, I was able to obtain a photo. I'm very sorry for the quality, just wanted to provide
>> something for now.
> 
> Sorry it took me so long - my attempts to coordinate setting up serial console
> were not successful, so it had to wait for me to go there in person...
> 
> I have attached complete dmesg, summary:
> 
> [   10.905953] rtmutex deadlock detected
> [   10.909959] WARNING: CPU: 5 PID: 83 at kernel/locking/rtmutex.c:1642 __rt_mutex_slowlock_locked.constprop.0+0x10f/0x1a5
> [   10.920961] CPU: 5 PID: 83 Comm: kworker/u16:3 Not tainted 6.6.34-o5 #1
> [   10.929970] Hardware name: Dell Inc. PowerEdge T110 II/0PM2CW, BIOS 2.10.0 05/24/2018
> [   10.938954] Workqueue: events_unbound async_run_entry_fn
> 
> 
> [   11.336954] BUG: scheduling while atomic: kworker/u16:3/83/0x00000002
> [   11.342953] Preemption disabled at:
> [   11.342953] [<0000000000000000>] 0x0
> [   11.350953] CPU: 5 PID: 83 Comm: kworker/u16:3 Tainted: G        W          6.6.34-o5 #1
> [   11.361954] Hardware name: Dell Inc. PowerEdge T110 II/0PM2CW, BIOS 2.10.0 05/24/2018
> [   11.369953] Workqueue: events_unbound async_run_entry_fn
> 
Thanks a lot for the comprehensive info. Reason for the deadlock is that calls to
i2c_new_client_device() can be nested. So another solution approach is needed.
I'd appreciate if you could test also the new version below.

> 
> 
> Krzysztof

Heiner

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index b63f75e44..c1074d409 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -915,6 +915,29 @@ int i2c_dev_irq_from_resources(const struct resource *resources,
 	return 0;
 }
 
+/**
+ * Serialize device instantiation in case it can be instantiated explicitly
+ * and by auto-detection
+ */
+static int i2c_test_and_set_addr_in_instantiation(struct i2c_adapter *adap,
+						  const struct i2c_client *client)
+{
+	if (!(client->flags & I2C_CLIENT_TEN) &&
+	    !(client->flags & I2C_CLIENT_SLAVE) &&
+	    test_and_set_bit(client->addr, adap->addrs_in_instantiation))
+		return -EBUSY;
+
+	return 0;
+}
+
+static void i2c_clear_addr_in_instantiation(struct i2c_adapter *adap,
+					    const struct i2c_client *client)
+{
+	if (!(client->flags & I2C_CLIENT_TEN) &&
+	    !(client->flags & I2C_CLIENT_SLAVE))
+		clear_bit(client->addr, adap->addrs_in_instantiation);
+}
+
 /**
  * i2c_new_client_device - instantiate an i2c device
  * @adap: the adapter managing the device
@@ -962,6 +985,10 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
 		goto out_err_silent;
 	}
 
+	status = i2c_test_and_set_addr_in_instantiation(adap, client);
+	if (status)
+		goto out_err_silent;
+
 	/* Check for address business */
 	status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client));
 	if (status)
@@ -993,6 +1020,8 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
 	dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
 		client->name, dev_name(&client->dev));
 
+	i2c_clear_addr_in_instantiation(adap, client);
+
 	return client;
 
 out_remove_swnode:
@@ -1004,6 +1033,7 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
 	dev_err(&adap->dev,
 		"Failed to register i2c client %s at 0x%02x (%d)\n",
 		client->name, client->addr, status);
+	i2c_clear_addr_in_instantiation(adap, client);
 out_err_silent:
 	if (need_put)
 		put_device(&client->dev);
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 07e33bbc9..31486455f 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -761,6 +761,9 @@ struct i2c_adapter {
 	struct regulator *bus_regulator;
 
 	struct dentry *debugfs;
+
+	/* covers 7bit addresses only */
+	DECLARE_BITMAP(addrs_in_instantiation, 1 << 7);
 };
 #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
 
-- 
2.46.0