Re: BUG in i2c_detach_client

[Andrew James Wade <ajwade@cpe00095b3131a0-cm0011ae8cd564.cpe.net.cable.rogers.com>]

On June 8, 2005 05:26 pm, Andrew Morton wrote:
> Were there no interesting printks before this BUG hit?
Nope :-(

> It's due to the kernel running list_del() on a list_head which isn't on a list.
> 
> Seems there is an error-path bug in that driver, but I don' thtink the fix
> will fix it.  Please test?
Will do. But I don't think that's it. I've been adding printks to determine the
execution path and it goes through the ERROR3 path in asb100_detect(), which means
AFACT that the error path in asb100_detect_subclients() isn't taken:

ERROR3:
        i2c_detach_client(data->lm75[0]);
        kfree(data->lm75[1]);
        kfree(data->lm75[0]);
ERROR2:
        i2c_detach_client(new_client); // <--- BUG() in here.
ERROR1:
        kfree(data);
ERROR0:
        return err;

But the ERROR2 path does work despite the location of the bug. If I apply:

--- 2.6.12-rc6-mm1/drivers/i2c/chips/asb100.c   2005-06-08 17:46:02.123864000 -0400
+++ linux/drivers/i2c/chips/asb100.c    2005-06-08 17:59:21.461819500 -0400
@@ -811,6 +811,7 @@ static int asb100_detect(struct i2c_adap
        if ((err = i2c_attach_client(new_client)))
                goto ERROR1;

+        goto ERROR2;
        /* Attach secondary lm75 clients */
        if ((err = asb100_detect_subclients(adapter, address, kind,
                        new_client)))
@@ -874,7 +875,6 @@ static int asb100_detach_client(struct i
 {
        int err;

-       hwmon_device_unregister(client->class_dev);

        if ((err = i2c_detach_client(client))) {
                dev_err(&client->dev, "client deregistration failed; "

No bug(). But the ERROR3 path doesn't:
--- 2.6.12-rc6-mm1/drivers/i2c/chips/asb100.c   2005-06-08 17:46:02.123864000 -0400
+++ linux/drivers/i2c/chips/asb100.c    2005-06-08 17:58:15.749712750 -0400
@@ -815,6 +815,7 @@ static int asb100_detect(struct i2c_adap
        if ((err = asb100_detect_subclients(adapter, address, kind,
                        new_client)))
                goto ERROR2;
+        goto ERROR3;

        /* Initialize the chip */
        asb100_init_client(new_client);
@@ -874,7 +875,6 @@ static int asb100_detach_client(struct i
 {
        int err;

-       hwmon_device_unregister(client->class_dev);

        if ((err = i2c_detach_client(client))) {
                dev_err(&client->dev, "client deregistration failed; "

causes a BUG(). I've yet to track the problem down further. Unfortunately
I have no more time today, I'll play with it again tomorrow.

Regards,
Andrew
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