lm75_remove: LM75 Device remove using sysfs delete_device

lm75_remove: LM75 Device remove using sysfs delete_device

[Sasikanth babu]

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Hi all,

  when I'm trying to delete lm75 device using sysfs delete_device attribute
(echo 0x4e >/sys/bus/i2c/devices/i2c-3/delete_device)
  It hangs at lm75_remove function. I started the device using sysfs
attribute new_device.


  Kernel verion : 2.6.34.12

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
i2cinit       D ffffffff814a04e0     0  2064   2059 0x00000004
 ffff880271928a70 0000000000000086 0000000000000096 ffff880273215b48
 ffff8802ffffffff ffff880477306a70 0000000000010140 ffff880273215fd8
 0000000000010140 ffff880271928a70 ffff880273215fd8 ffff880273215fd8
Call Trace:
 [<ffffffff8103ecd0>] ? default_wake_function+0x0/0x20
 [<ffffffff8148765f>] ? __rt_mutex_slowlock+0x4f/0x110
 [<ffffffff814879e3>] ? rt_mutex_slowlock+0x93/0x190
 [<ffffffff813278d9>] ? i2c_smbus_xfer+0x49/0x110
 [<ffffffff814e1de0>] ? dev_sysfs_ops+0x0/0x10
 [<ffffffff81327c40>] ? i2c_smbus_write_byte_data+0x30/0x40
 [<ffffffff811361f9>] ? sysfs_remove_group+0x59/0x100
 [<ffffffff8132ec2d>] ? lm75_remove+0x4d/0x80
 [<ffffffff81326ef9>] ? i2c_device_remove+0xa9/0xc0
 [<ffffffff8129ffb6>] ? __device_release_driver+0x56/0xc0
 [<ffffffff812a00f5>] ? device_release_driver+0x25/0x40
 [<ffffffff8129f481>] ? bus_remove_device+0x91/0xc0
 [<ffffffff8129d7a8>] ? device_del+0x118/0x190
 [<ffffffff8129d829>] ? device_unregister+0x9/0x20
 [<ffffffff813281bc>] ? i2c_sysfs_delete_device+0x17c/0x200
 [<ffffffff81133046>] ? sysfs_write_file+0x1c6/0x260
 [<ffffffff810d5323>] ? vfs_write+0x103/0x200
 [<ffffffff810d550e>] ? sys_write+0x4e/0x90
 [<ffffffff814884e4>] ? page_fault+0x24/0x30
 [<ffffffff810024ab>] ? system_call_done+0x0/0x5

Thanks in advance for your help.

Thanks
Sasi

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Re: [lm-sensors] lm75_remove: LM75 Device remove using sysfs delete_device

[Guenter Roeck]

On Sun, Jun 10, 2012 at 10:41:03AM -0400, Sasikanth babu wrote:
> Hi all,
> 
>   when I'm trying to delete lm75 device using sysfs delete_device attribute
> (echo 0x4e >/sys/bus/i2c/devices/i2c-3/delete_device)
>   It hangs at lm75_remove function. I started the device using sysfs attribute
> new_device.
> 
> 
>   Kernel verion : 2.6.34.12
> 
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> i2cinit       D ffffffff814a04e0     0  2064   2059 0x00000004
>  ffff880271928a70 0000000000000086 0000000000000096 ffff880273215b48
>  ffff8802ffffffff ffff880477306a70 0000000000010140 ffff880273215fd8
>  0000000000010140 ffff880271928a70 ffff880273215fd8 ffff880273215fd8
> Call Trace:
>  [<ffffffff8103ecd0>] ? default_wake_function+0x0/0x20
>  [<ffffffff8148765f>] ? __rt_mutex_slowlock+0x4f/0x110
>  [<ffffffff814879e3>] ? rt_mutex_slowlock+0x93/0x190
>  [<ffffffff813278d9>] ? i2c_smbus_xfer+0x49/0x110
>  [<ffffffff814e1de0>] ? dev_sysfs_ops+0x0/0x10
>  [<ffffffff81327c40>] ? i2c_smbus_write_byte_data+0x30/0x40
>  [<ffffffff811361f9>] ? sysfs_remove_group+0x59/0x100
>  [<ffffffff8132ec2d>] ? lm75_remove+0x4d/0x80
>  [<ffffffff81326ef9>] ? i2c_device_remove+0xa9/0xc0
>  [<ffffffff8129ffb6>] ? __device_release_driver+0x56/0xc0
>  [<ffffffff812a00f5>] ? device_release_driver+0x25/0x40
>  [<ffffffff8129f481>] ? bus_remove_device+0x91/0xc0
>  [<ffffffff8129d7a8>] ? device_del+0x118/0x190
>  [<ffffffff8129d829>] ? device_unregister+0x9/0x20
>  [<ffffffff813281bc>] ? i2c_sysfs_delete_device+0x17c/0x200
>  [<ffffffff81133046>] ? sysfs_write_file+0x1c6/0x260
>  [<ffffffff810d5323>] ? vfs_write+0x103/0x200
>  [<ffffffff810d550e>] ? sys_write+0x4e/0x90
>  [<ffffffff814884e4>] ? page_fault+0x24/0x30
>  [<ffffffff810024ab>] ? system_call_done+0x0/0x5
> 

Hi,

I don't see anything wrong in the lm75 driver. The problem seems to be related
to the I2C bus master driver, or possibly to another device access pending on the
same I2C bus which does not complete.

What is the I2C bus master driver, and do you have anything else happening on the same bus ?

Guenter

Re: lm75_remove: LM75 Device remove using sysfs delete_device

[Jean Delvare]

(Note: Frodo is out of the lm-sensors project for years, no need to Cc
him.)

On Sun, 10 Jun 2012 07:41:03 -0700, Sasikanth babu wrote:
>   when I'm trying to delete lm75 device using sysfs delete_device attribute
> (echo 0x4e >/sys/bus/i2c/devices/i2c-3/delete_device)
>   It hangs at lm75_remove function. I started the device using sysfs
> attribute new_device.
> 
> 
>   Kernel verion : 2.6.34.12

I can't reproduce this with kernel 3.4.2.

Did you try reproducing this with a more recent kernel? 2.6.34 is
getting old.

Is there anything you can think of which makes your system special? I2C
bus multiplexing ? Some unusual kernel option maybe?

> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> i2cinit       D ffffffff814a04e0     0  2064   2059 0x00000004
>  ffff880271928a70 0000000000000086 0000000000000096 ffff880273215b48
>  ffff8802ffffffff ffff880477306a70 0000000000010140 ffff880273215fd8
>  0000000000010140 ffff880271928a70 ffff880273215fd8 ffff880273215fd8
> Call Trace:
>  [<ffffffff8103ecd0>] ? default_wake_function+0x0/0x20
>  [<ffffffff8148765f>] ? __rt_mutex_slowlock+0x4f/0x110
>  [<ffffffff814879e3>] ? rt_mutex_slowlock+0x93/0x190
>  [<ffffffff813278d9>] ? i2c_smbus_xfer+0x49/0x110
>  [<ffffffff814e1de0>] ? dev_sysfs_ops+0x0/0x10
>  [<ffffffff81327c40>] ? i2c_smbus_write_byte_data+0x30/0x40

This looks odd, sysfs_remove_group() doesn't call
i2c_smbus_write_byte_data(), and i2c_smbus_write_byte_data() doesn't
touch dev_sysfs_ops... So this stack trace is approximate.

>  [<ffffffff811361f9>] ? sysfs_remove_group+0x59/0x100
>  [<ffffffff8132ec2d>] ? lm75_remove+0x4d/0x80
>  [<ffffffff81326ef9>] ? i2c_device_remove+0xa9/0xc0
>  [<ffffffff8129ffb6>] ? __device_release_driver+0x56/0xc0
>  [<ffffffff812a00f5>] ? device_release_driver+0x25/0x40
>  [<ffffffff8129f481>] ? bus_remove_device+0x91/0xc0
>  [<ffffffff8129d7a8>] ? device_del+0x118/0x190
>  [<ffffffff8129d829>] ? device_unregister+0x9/0x20
>  [<ffffffff813281bc>] ? i2c_sysfs_delete_device+0x17c/0x200
>  [<ffffffff81133046>] ? sysfs_write_file+0x1c6/0x260
>  [<ffffffff810d5323>] ? vfs_write+0x103/0x200
>  [<ffffffff810d550e>] ? sys_write+0x4e/0x90
>  [<ffffffff814884e4>] ? page_fault+0x24/0x30
>  [<ffffffff810024ab>] ? system_call_done+0x0/0x5

-- 
Jean Delvare

Re: [lm-sensors] lm75_remove: LM75 Device remove using sysfs delete_device

[Guenter Roeck]

On Sun, Jun 10, 2012 at 11:36:40AM -0400, Jean Delvare wrote:
> (Note: Frodo is out of the lm-sensors project for years, no need to Cc
> him.)
> 
> On Sun, 10 Jun 2012 07:41:03 -0700, Sasikanth babu wrote:
> >   when I'm trying to delete lm75 device using sysfs delete_device attribute
> > (echo 0x4e >/sys/bus/i2c/devices/i2c-3/delete_device)
> >   It hangs at lm75_remove function. I started the device using sysfs
> > attribute new_device.
> > 
> > 
> >   Kernel verion : 2.6.34.12
> 
> I can't reproduce this with kernel 3.4.2.
> 
> Did you try reproducing this with a more recent kernel? 2.6.34 is
> getting old.
> 
> Is there anything you can think of which makes your system special? I2C
> bus multiplexing ? Some unusual kernel option maybe?
> 
> > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> > i2cinit       D ffffffff814a04e0     0  2064   2059 0x00000004
> >  ffff880271928a70 0000000000000086 0000000000000096 ffff880273215b48
> >  ffff8802ffffffff ffff880477306a70 0000000000010140 ffff880273215fd8
> >  0000000000010140 ffff880271928a70 ffff880273215fd8 ffff880273215fd8
> > Call Trace:
> >  [<ffffffff8103ecd0>] ? default_wake_function+0x0/0x20
> >  [<ffffffff8148765f>] ? __rt_mutex_slowlock+0x4f/0x110
> >  [<ffffffff814879e3>] ? rt_mutex_slowlock+0x93/0x190
> >  [<ffffffff813278d9>] ? i2c_smbus_xfer+0x49/0x110
> >  [<ffffffff814e1de0>] ? dev_sysfs_ops+0x0/0x10
> >  [<ffffffff81327c40>] ? i2c_smbus_write_byte_data+0x30/0x40
> 
> This looks odd, sysfs_remove_group() doesn't call
> i2c_smbus_write_byte_data(), and i2c_smbus_write_byte_data() doesn't
> touch dev_sysfs_ops... So this stack trace is approximate.
> 
I thought it was probably the call to lm75_write_value() in lm75_remove()
after sysfs_remove_group() returned.

Guenter 

> >  [<ffffffff811361f9>] ? sysfs_remove_group+0x59/0x100
> >  [<ffffffff8132ec2d>] ? lm75_remove+0x4d/0x80
> >  [<ffffffff81326ef9>] ? i2c_device_remove+0xa9/0xc0
> >  [<ffffffff8129ffb6>] ? __device_release_driver+0x56/0xc0
> >  [<ffffffff812a00f5>] ? device_release_driver+0x25/0x40
> >  [<ffffffff8129f481>] ? bus_remove_device+0x91/0xc0
> >  [<ffffffff8129d7a8>] ? device_del+0x118/0x190
> >  [<ffffffff8129d829>] ? device_unregister+0x9/0x20
> >  [<ffffffff813281bc>] ? i2c_sysfs_delete_device+0x17c/0x200
> >  [<ffffffff81133046>] ? sysfs_write_file+0x1c6/0x260
> >  [<ffffffff810d5323>] ? vfs_write+0x103/0x200
> >  [<ffffffff810d550e>] ? sys_write+0x4e/0x90
> >  [<ffffffff814884e4>] ? page_fault+0x24/0x30
> >  [<ffffffff810024ab>] ? system_call_done+0x0/0x5
> 
> -- 
> Jean Delvare
> 
> _______________________________________________
> lm-sensors mailing list
> lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org
> http://lists.lm-sensors.org/mailman/listinfo/lm-sensors

Re: lm75_remove: LM75 Device remove using sysfs delete_device

[Jean Delvare]

On Sun, 10 Jun 2012 08:46:29 -0700, Guenter Roeck wrote:
> On Sun, Jun 10, 2012 at 11:36:40AM -0400, Jean Delvare wrote:
> > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> > > i2cinit       D ffffffff814a04e0     0  2064   2059 0x00000004
> > >  ffff880271928a70 0000000000000086 0000000000000096 ffff880273215b48
> > >  ffff8802ffffffff ffff880477306a70 0000000000010140 ffff880273215fd8
> > >  0000000000010140 ffff880271928a70 ffff880273215fd8 ffff880273215fd8
> > > Call Trace:
> > >  [<ffffffff8103ecd0>] ? default_wake_function+0x0/0x20
> > >  [<ffffffff8148765f>] ? __rt_mutex_slowlock+0x4f/0x110
> > >  [<ffffffff814879e3>] ? rt_mutex_slowlock+0x93/0x190
> > >  [<ffffffff813278d9>] ? i2c_smbus_xfer+0x49/0x110
> > >  [<ffffffff814e1de0>] ? dev_sysfs_ops+0x0/0x10
> > >  [<ffffffff81327c40>] ? i2c_smbus_write_byte_data+0x30/0x40
> > 
> > This looks odd, sysfs_remove_group() doesn't call
> > i2c_smbus_write_byte_data(), and i2c_smbus_write_byte_data() doesn't
> > touch dev_sysfs_ops... So this stack trace is approximate.
> > 
> I thought it was probably the call to lm75_write_value() in lm75_remove()
> after sysfs_remove_group() returned.

Certainly. We see a mix of the function calls in lm75_remove().
lm75_write_value() is definitely the one causing the deadlock. And your
analysis is correct... there's nothing special about this byte write,
so there must be something wrong with the underlying I2C bus even
before that.

-- 
Jean Delvare

Re: lm75_remove: LM75 Device remove using sysfs delete_device

[Sasikanth babu]

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On Sun, Jun 10, 2012 at 9:06 PM, Jean Delvare <khali@linux-fr.org> wrote:

> (Note: Frodo is out of the lm-sensors project for years, no need to Cc
> him.)
>
> On Sun, 10 Jun 2012 07:41:03 -0700, Sasikanth babu wrote:
> >   when I'm trying to delete lm75 device using sysfs delete_device
> attribute
> > (echo 0x4e >/sys/bus/i2c/devices/i2c-3/delete_device)
> >   It hangs at lm75_remove function. I started the device using sysfs
> > attribute new_device.
> >
> >
> >   Kernel verion : 2.6.34.12
>
> I can't reproduce this with kernel 3.4.2.
>
> Did you try reproducing this with a more recent kernel? 2.6.34 is
> getting old.
>
> Is there anything you can think of which makes your system special? I2C
> bus multiplexing ? Some unusual kernel option maybe?
>

      Yes, I have PCA9545 Mux device. LM75 device was connected to PCA9545
Mux devices (Mux device
      is connected to SMBUS). At first I unloaded PCA954x module, It hanged
at lm75_remove. Later I had
      to tried remove the lm75 device using sysfs, again it hanged at same
location. Both PCA Mux device and
      lm75 devvice instantiated using sysfs new_device.

>
> > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> > i2cinit       D ffffffff814a04e0     0  2064   2059 0x00000004
> >  ffff880271928a70 0000000000000086 0000000000000096 ffff880273215b48
> >  ffff8802ffffffff ffff880477306a70 0000000000010140 ffff880273215fd8
> >  0000000000010140 ffff880271928a70 ffff880273215fd8 ffff880273215fd8
> > Call Trace:
> >  [<ffffffff8103ecd0>] ? default_wake_function+0x0/0x20
> >  [<ffffffff8148765f>] ? __rt_mutex_slowlock+0x4f/0x110
> >  [<ffffffff814879e3>] ? rt_mutex_slowlock+0x93/0x190
> >  [<ffffffff813278d9>] ? i2c_smbus_xfer+0x49/0x110
> >  [<ffffffff814e1de0>] ? dev_sysfs_ops+0x0/0x10
> >  [<ffffffff81327c40>] ? i2c_smbus_write_byte_data+0x30/0x40
>
> This looks odd, sysfs_remove_group() doesn't call
> i2c_smbus_write_byte_data(), and i2c_smbus_write_byte_data() doesn't
> touch dev_sysfs_ops... So this stack trace is approximate.
>
> >  [<ffffffff811361f9>] ? sysfs_remove_group+0x59/0x100
> >  [<ffffffff8132ec2d>] ? lm75_remove+0x4d/0x80
> >  [<ffffffff81326ef9>] ? i2c_device_remove+0xa9/0xc0
> >  [<ffffffff8129ffb6>] ? __device_release_driver+0x56/0xc0
> >  [<ffffffff812a00f5>] ? device_release_driver+0x25/0x40
> >  [<ffffffff8129f481>] ? bus_remove_device+0x91/0xc0
> >  [<ffffffff8129d7a8>] ? device_del+0x118/0x190
> >  [<ffffffff8129d829>] ? device_unregister+0x9/0x20
> >  [<ffffffff813281bc>] ? i2c_sysfs_delete_device+0x17c/0x200
> >  [<ffffffff81133046>] ? sysfs_write_file+0x1c6/0x260
> >  [<ffffffff810d5323>] ? vfs_write+0x103/0x200
> >  [<ffffffff810d550e>] ? sys_write+0x4e/0x90
> >  [<ffffffff814884e4>] ? page_fault+0x24/0x30
> >  [<ffffffff810024ab>] ? system_call_done+0x0/0x5
>
> --
> Jean Delvare
>

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Re: lm75_remove: LM75 Device remove using sysfs delete_device

[Guenter Roeck]

On Tue, Jun 12, 2012 at 11:51:51PM -0400, Sasikanth babu wrote:
> 
> On Sun, Jun 10, 2012 at 9:06 PM, Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org> wrote:
> 
>     (Note: Frodo is out of the lm-sensors project for years, no need to Cc
>     him.)
> 
>     On Sun, 10 Jun 2012 07:41:03 -0700, Sasikanth babu wrote:
>     >   when I'm trying to delete lm75 device using sysfs delete_device
>     attribute
>     > (echo 0x4e >/sys/bus/i2c/devices/i2c-3/delete_device)
>     >   It hangs at lm75_remove function. I started the device using sysfs
>     > attribute new_device.
>     >
>     >
>     >   Kernel verion : 2.6.34.12
> 
>     I can't reproduce this with kernel 3.4.2.
> 
>     Did you try reproducing this with a more recent kernel? 2.6.34 is
>     getting old.
> 
>     Is there anything you can think of which makes your system special? I2C
>     bus multiplexing ? Some unusual kernel option maybe?
> 
>    
>       Yes, I have PCA9545 Mux device. LM75 device was connected to PCA9545 Mux
> devices (Mux device
>       is connected to SMBUS). At first I unloaded PCA954x module, It hanged at
> lm75_remove. Later I had
>       to tried remove the lm75 device using sysfs, again it hanged at same
> location. Both PCA Mux device and
>       lm75 devvice instantiated using sysfs new_device.
> 
> 
>     > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>     > i2cinit       D ffffffff814a04e0     0  2064   2059 0x00000004
>     >  ffff880271928a70 0000000000000086 0000000000000096 ffff880273215b48
>     >  ffff8802ffffffff ffff880477306a70 0000000000010140 ffff880273215fd8
>     >  0000000000010140 ffff880271928a70 ffff880273215fd8 ffff880273215fd8
>     > Call Trace:
>     >  [<ffffffff8103ecd0>] ? default_wake_function+0x0/0x20
>     >  [<ffffffff8148765f>] ? __rt_mutex_slowlock+0x4f/0x110
>     >  [<ffffffff814879e3>] ? rt_mutex_slowlock+0x93/0x190
>     >  [<ffffffff813278d9>] ? i2c_smbus_xfer+0x49/0x110
>     >  [<ffffffff814e1de0>] ? dev_sysfs_ops+0x0/0x10
>     >  [<ffffffff81327c40>] ? i2c_smbus_write_byte_data+0x30/0x40
> 
>     This looks odd, sysfs_remove_group() doesn't call
>     i2c_smbus_write_byte_data(), and i2c_smbus_write_byte_data() doesn't
>     touch dev_sysfs_ops... So this stack trace is approximate.
> 
>     >  [<ffffffff811361f9>] ? sysfs_remove_group+0x59/0x100
>     >  [<ffffffff8132ec2d>] ? lm75_remove+0x4d/0x80
>     >  [<ffffffff81326ef9>] ? i2c_device_remove+0xa9/0xc0
>     >  [<ffffffff8129ffb6>] ? __device_release_driver+0x56/0xc0
>     >  [<ffffffff812a00f5>] ? device_release_driver+0x25/0x40
>     >  [<ffffffff8129f481>] ? bus_remove_device+0x91/0xc0
>     >  [<ffffffff8129d7a8>] ? device_del+0x118/0x190
>     >  [<ffffffff8129d829>] ? device_unregister+0x9/0x20
>     >  [<ffffffff813281bc>] ? i2c_sysfs_delete_device+0x17c/0x200
>     >  [<ffffffff81133046>] ? sysfs_write_file+0x1c6/0x260
>     >  [<ffffffff810d5323>] ? vfs_write+0x103/0x200
>     >  [<ffffffff810d550e>] ? sys_write+0x4e/0x90
>     >  [<ffffffff814884e4>] ? page_fault+0x24/0x30
>     >  [<ffffffff810024ab>] ? system_call_done+0x0/0x5
> 
Jean,

in 2.6.34, i2c_sysfs_delete_device calls i2c_lock_adapter, then i2c_unregister_device.
This in turn calls lm75_remove which through i2c_smbus_xfer tries to acquire the lock again.

The current code is different - i2c_sysfs_delete_device no longer calls i2c_lock_adapter.
Commit ID is dafc50d141c27959dbd3a1cfe9857a86d23402a7, which specifically mentions deadlock
issues with multiplexed busses.

Guenter