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

[Guenter Roeck <guenter.roeck-IzeFyvvaP7pWk0Htik3J/w@public.gmane.org>]

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
> 
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