Re: [crash, bisected] I2C, kobject (ffff81003e8c4160): tried to init an initialized object

Jean Delvare
2008-07-16T12:18:54Z

Hi Ingo, John,

Thanks a lot for reporting this bug quickly, BTW.

On Wed, 16 Jul 2008 12:08:01 +0200, Jean Delvare wrote:
> On Wed, 16 Jul 2008 11:07:02 +0200, Jean Delvare wrote:
> > On Wed, 16 Jul 2008 10:23:52 +0200, Ingo Molnar wrote:
> > >
> > > * Jean Delvare <khali@linux-fr.org> wrote:
> > >
> > > > i2c-nforce2: Add support for multiplexing on the Tyan S4985
> > >
> > > -tip random boot testing started triggering the following upstream boot
> > > crash, starting two days ago when the i2c tree was merged:
> > >
> > > [ 11.772002] kobject (ffff81003e8c4160): tried to init an initialized object, something is seriously wrong.
> > > [ 11.784004] Pid: 1, comm: swapper Not tainted 2.6.26-00007-g279e902-dirty #19896
> > > [ 11.793651]
> > > [ 11.793651] Call Trace:
> > > [ 11.793651] [<ffffffff8054471a>] kobject_init+0x7a/0x80
> > > [ 11.798969] [<ffffffff805f0f9d>] device_initialize+0x2d/0xd0
> > > [ 11.806323] [<ffffffff805f19a1>] device_register+0x11/0x20
> > > [ 11.811903] [<ffffffff8087ee3b>] i2c_register_adapter+0xab/0x1d0
> > > [ 11.817666] [<ffffffff8087f0e6>] i2c_add_adapter+0x96/0xb0
> > > [ 11.823761] [<ffffffff81196372>] nforce2_s4985_init+0x272/0x370
> > > [ 11.829358] [<ffffffff8027516a>] ? getnstimeofday+0x3a/0xc0
> > > [ 11.835365] [<ffffffff802728ba>] ? ktime_get_ts+0x4a/0x60
> > > [ 11.840853] [<ffffffff81196100>] ? nforce2_s4985_init+0x0/0x370
> > > [ 11.846859] [<ffffffff81160aa3>] kernel_init+0x123/0x300
> > > [ 11.852261] [<ffffffff81160140>] ? early_idt_handler+0x0/0x74
> > > [ 11.857957] [<ffffffff80228548>] child_rip+0xa/0x12
> > > [ 11.863781] [<ffffffff81160140>] ? early_idt_handler+0x0/0x74
> > > [ 11.868757] [<ffffffff81160980>] ? kernel_init+0x0/0x300
> > > [ 11.874160] [<ffffffff8022853e>] ? child_rip+0x0/0x12
> > > [ 11.879989]
> > > [ 11.881141] general protection fault: 0000 [1] SMP
> > > [ 11.881141] CPU 1
>
> Good news: I can reproduce this locally. Stay tuned...

OK, here's the fix. I'll push it to Linus later today, unless someone
objects. I've tested it on a board without multiplexing. It would be
great if someone could now test on a board with multiplexing, just to
make sure I didn't break anything. Ulrich?

* * * * *

From: Jean Delvare <khali@linux-fr.org>
Subject: i2c: Clear i2c_adapter.dev on adapter removal

Clear i2c_adapter.dev on adapter removal. This makes it possible to
re-add the adapter at a later point, which some drivers
(i2c-amd756-s4882, i2c-nforce2-s4985) actually do.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
drivers/i2c/busses/i2c-amd756-s4882.c | 27 +++++++++++++--------------
drivers/i2c/busses/i2c-nforce2-s4985.c | 31 +++++++++++++++----------------
drivers/i2c/i2c-core.c | 4 ++++
3 files changed, 32 insertions(+), 30 deletions(-)

--- linux-2.6.27-rc0.orig/drivers/i2c/i2c-core.c 2008-07-16 13:13:00.000000000 +0200
+++ linux-2.6.27-rc0/drivers/i2c/i2c-core.c 2008-07-16 13:27:48.000000000 +0200
@@ -654,6 +654,10 @@ int i2c_del_adapter(struct i2c_adapter *

dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);

+ /* Clear the device structure in case this adapter is ever going to be
+ added again */
+ memset(&adap->dev, 0, sizeof(adap->dev));
+
out_unlock:
mutex_unlock(&core_lock);
return res;
--- linux-2.6.27-rc0.orig/drivers/i2c/busses/i2c-nforce2-s4985.c 2008-07-16 10:41:52.000000000 +0200
+++ linux-2.6.27-rc0/drivers/i2c/busses/i2c-nforce2-s4985.c 2008-07-16 13:58:43.000000000 +0200
@@ -150,6 +150,16 @@ static int __init nforce2_s4985_init(voi
int i, error;
union i2c_smbus_data ioconfig;

+ /* Configure the PCA9556 multiplexer */
+ ioconfig.byte = 0x00; /* All I/O to output mode */
+ error = i2c_smbus_xfer(nforce2_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
+ I2C_SMBUS_BYTE_DATA, &ioconfig);
+ if (error) {
+ dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n");
+ error = -EIO;
+ goto ERROR0;
+ }
+
/* Unregister physical bus */
if (!nforce2_smbus)
return -ENODEV;
@@ -191,24 +201,13 @@ static int __init nforce2_s4985_init(voi
s4985_algo[3].smbus_xfer = nforce2_access_virt3;
s4985_algo[4].smbus_xfer = nforce2_access_virt4;

- /* Configure the PCA9556 multiplexer */
- ioconfig.byte = 0x00; /* All I/O to output mode */
- error = nforce2_smbus->algo->smbus_xfer(nforce2_smbus, 0x18, 0,
- I2C_SMBUS_WRITE, 0x03,
- I2C_SMBUS_BYTE_DATA, &ioconfig);
- if (error) {
- dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n");
- error = -EIO;
- goto ERROR3;
- }
-
/* Register virtual adapters */
for (i = 0; i < 5; i++) {
error = i2c_add_adapter(s4985_adapter + i);
if (error) {
- dev_err(&nforce2_smbus->dev,
- "Virtual adapter %d registration "
- "failed, module not inserted\n", i);
+ printk(KERN_ERR "i2c-nforce2-s4985: "
+ "Virtual adapter %d registration "
+ "failed, module not inserted\n", i);
for (i--; i >= 0; i--)
i2c_del_adapter(s4985_adapter + i);
goto ERROR3;
@@ -245,8 +244,8 @@ static void __exit nforce2_s4985_exit(vo

/* Restore physical bus */
if (i2c_add_adapter(nforce2_smbus))
- dev_err(&nforce2_smbus->dev, "Physical bus restoration "
- "failed\n");
+ printk(KERN_ERR "i2c-nforce2-s4985: "
+ "Physical bus restoration failed\n");
}

MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
--- linux-2.6.27-rc0.orig/drivers/i2c/busses/i2c-amd756-s4882.c 2008-07-16 10:41:52.000000000 +0200
+++ linux-2.6.27-rc0/drivers/i2c/busses/i2c-amd756-s4882.c 2008-07-16 13:58:25.000000000 +0200
@@ -155,6 +155,16 @@ static int __init amd756_s4882_init(void
int i, error;
union i2c_smbus_data ioconfig;

+ /* Configure the PCA9556 multiplexer */
+ ioconfig.byte = 0x00; /* All I/O to output mode */
+ error = i2c_smbus_xfer(&amd756_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
+ I2C_SMBUS_BYTE_DATA, &ioconfig);
+ if (error) {
+ dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
+ error = -EIO;
+ goto ERROR0;
+ }
+
/* Unregister physical bus */
error = i2c_del_adapter(&amd756_smbus);
if (error) {
@@ -198,22 +208,11 @@ static int __init amd756_s4882_init(void
s4882_algo[3].smbus_xfer = amd756_access_virt3;
s4882_algo[4].smbus_xfer = amd756_access_virt4;

- /* Configure the PCA9556 multiplexer */
- ioconfig.byte = 0x00; /* All I/O to output mode */
- error = amd756_smbus.algo->smbus_xfer(&amd756_smbus, 0x18, 0,
- I2C_SMBUS_WRITE, 0x03,
- I2C_SMBUS_BYTE_DATA, &ioconfig);
- if (error) {
- dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
- error = -EIO;
- goto ERROR3;
- }
-
/* Register virtual adapters */
for (i = 0; i < 5; i++) {
error = i2c_add_adapter(s4882_adapter+i);
if (error) {
- dev_err(&amd756_smbus.dev,
+ printk(KERN_ERR "i2c-amd756-s4882: "
"Virtual adapter %d registration "
"failed, module not inserted\n", i);
for (i--; i >= 0; i--)
@@ -252,8 +251,8 @@ static void __exit amd756_s4882_exit(voi

/* Restore physical bus */
if (i2c_add_adapter(&amd756_smbus))
- dev_err(&amd756_smbus.dev, "Physical bus restoration "
- "failed\n");
+ printk(KERN_ERR "i2c-amd756-s4882: "
+ "Physical bus restoration failed\n");
}

MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");

--
Jean Delvare