Subject: Re: i2c_powermac: Kernel access of bad area

From: Benjamin Herrenschmidt <[email-masked]>
Date: Sat, 30 Jan 2010 08:34:55 +1100

> Ben, what about applying this patch of mine, as Christian reported it
> fixed his oops?

Sure. I never quite know with i2c which ones you will apply directly and
which ones you want to go through my tree :-)

Hopefully they should still be referened on patchwork, I'll dig there
and pick them up.

Cheers,
Ben.

> > > However, the "Badness" remains when I try to modprobe i2c-powermac again:
> > > 
> > > [  442.148222] PowerMac i2c bus pmu 2 registered
> > > [  442.148792] PowerMac i2c bus pmu 1 registered
> > > [  442.149299] PowerMac i2c bus mac-io 0 registered
> > > [  442.163573] adt746x: ADT7467 initializing
> > > [  442.170072] adt746x: Lowering max temperatures from 73, 80, 109 to 67, 47, 67
> > > [  442.176559] PowerMac i2c bus uni-n 1 registered
> > > [  442.227115] sysfs: cannot create duplicate filename '/devices/ams'
> > > [  442.227697] ------------[ cut here ]------------
> > > [  442.228176] Badness at fs/sysfs/dir.c:487
> > > [  442.228642] NIP: c00eb71c LR: c00eb71c CTR: 00000000
> > > [  442.229117] REGS: eea0fa50 TRAP: 0700   Not tainted  (2.6.33-rc3)
> > > [  442.229592] MSR: 00029032 <EE,ME,CE,IR,DR>  CR: 42008444  XER: 00000000
> > > [  442.230151] TASK = eea10000[2821] 'modprobe' THREAD: eea0e000
> > > [  442.230191] GPR00: c00eb71c eea0fb00 eea10000 0000004c 000064c6 ffffffff ffffffff 00000000 
> > > [  442.230758] GPR08: efa71740 c03e0000 00000000 000064c6 44008428 10020390 100e0000 100df49c 
> > > [  442.231326] GPR16: 100b54c0 100df49c 100ddd20 1018fb08 100b5340 c03e674c c03e6720 c03ea044 
> > > [  442.231902] GPR24: 00000000 24008422 ffffffea eea0fb58 ef0e9000 ef0e9000 ef0a9ea0 ffffffef 
> > > [  442.233187] NIP [c00eb71c] sysfs_add_one+0x94/0xc0
> > > [  442.233695] LR [c00eb71c] sysfs_add_one+0x94/0xc0
> > > [  442.234363] Call Trace:
> > > 
> > > I've put the whole dmesg on:
> > > 
> > >    http://nerdbynature.de/bits/2.6.33-rc2/i2c_powermac/r1/
> > 
> > Hmm. Looks like a different but somewhat similar problem in the ams
> > driver: some code that is in ams_exit() (the module exit code) should
> > instead be called when the device (not module) is removed. It probably
> > doesn't make much of a difference in the PMU case, but in the I2C case
> > it does matter.
> > 
> > The following, totally untested patch may fix it. I make no guarantee
> > that my code isn't racy though, I'm not familiar enough with the ams
> > driver code to tell for sure.
> > 
> > ---
> >  drivers/hwmon/ams/ams-core.c |   11 +++++++----
> >  drivers/hwmon/ams/ams-i2c.c  |    2 ++
> >  drivers/hwmon/ams/ams-pmu.c  |    2 ++
> >  drivers/hwmon/ams/ams.h      |    1 +
> >  4 files changed, 12 insertions(+), 4 deletions(-)
> > 
> > --- linux-2.6.33-rc3.orig/drivers/hwmon/ams/ams-core.c	2009-06-10 05:05:27.000000000 +0200
> > +++ linux-2.6.33-rc3/drivers/hwmon/ams/ams-core.c	2010-01-07 17:14:25.000000000 +0100
> > @@ -213,7 +213,7 @@ int __init ams_init(void)
> >  	return -ENODEV;
> >  }
> >  
> > -void ams_exit(void)
> > +void ams_sensor_detach(void)
> >  {
> >  	/* Remove input device */
> >  	ams_input_exit();
> > @@ -221,9 +221,6 @@ void ams_exit(void)
> >  	/* Remove attributes */
> >  	device_remove_file(&ams_info.of_dev->dev, &dev_attr_current);
> >  
> > -	/* Shut down implementation */
> > -	ams_info.exit();
> > -
> >  	/* Flush interrupt worker
> >  	 *
> >  	 * We do this after ams_info.exit(), because an interrupt might
> > @@ -239,6 +236,12 @@ void ams_exit(void)
> >  	pmf_unregister_irq_client(&ams_freefall_client);
> >  }
> >  
> > +static void __exit ams_exit(void)
> > +{
> > +	/* Shut down implementation */
> > +	ams_info.exit();
> > +}
> > +
> >  MODULE_AUTHOR("Stelian Pop, Michael Hanselmann");
> >  MODULE_DESCRIPTION("Apple Motion Sensor driver");
> >  MODULE_LICENSE("GPL");
> > --- linux-2.6.33-rc3.orig/drivers/hwmon/ams/ams-i2c.c	2009-06-10 05:05:27.000000000 +0200
> > +++ linux-2.6.33-rc3/drivers/hwmon/ams/ams-i2c.c	2010-01-07 17:12:46.000000000 +0100
> > @@ -238,6 +238,8 @@ static int ams_i2c_probe(struct i2c_clie
> >  static int ams_i2c_remove(struct i2c_client *client)
> >  {
> >  	if (ams_info.has_device) {
> > +		ams_sensor_detach();
> > +
> >  		/* Disable interrupts */
> >  		ams_i2c_set_irq(AMS_IRQ_ALL, 0);
> >  
> > --- linux-2.6.33-rc3.orig/drivers/hwmon/ams/ams-pmu.c	2009-06-10 05:05:27.000000000 +0200
> > +++ linux-2.6.33-rc3/drivers/hwmon/ams/ams-pmu.c	2010-01-07 17:13:47.000000000 +0100
> > @@ -133,6 +133,8 @@ static void ams_pmu_get_xyz(s8 *x, s8 *y
> >  
> >  static void ams_pmu_exit(void)
> >  {
> > +	ams_sensor_detach();
> > +
> >  	/* Disable interrupts */
> >  	ams_pmu_set_irq(AMS_IRQ_ALL, 0);
> >  
> > --- linux-2.6.33-rc3.orig/drivers/hwmon/ams/ams.h	2009-06-10 05:05:27.000000000 +0200
> > +++ linux-2.6.33-rc3/drivers/hwmon/ams/ams.h	2010-01-07 17:11:43.000000000 +0100
> > @@ -61,6 +61,7 @@ extern struct ams ams_info;
> >  
> >  extern void ams_sensors(s8 *x, s8 *y, s8 *z);
> >  extern int ams_sensor_attach(void);
> > +extern void ams_sensor_detach(void);
> >  
> >  extern int ams_pmu_init(struct device_node *np);
> >  extern int ams_i2c_init(struct device_node *np);
> 
> Christian, did you ever test this second patch of mine? If you did,
> what was the outcome?
>