* [lm-sensors] I2C-virtual and locking?
@ 2006-03-17 18:54 Kumar Gala
2006-03-17 21:16 ` Kumar Gala
0 siblings, 1 reply; 5+ messages in thread
From: Kumar Gala @ 2006-03-17 18:54 UTC (permalink / raw)
To: lm-sensors
I'm looking at porting the i2c-virtual code from 2.4 to 2.6. One
thing I'm not clear on is the use of i2c_add_adapter_nolock() by the
old code. The only reference I can find related to this is:
http://archives.andrew.net.au/lm-sensors/msg31060.html
I can't think of a reason why locking would be in issue when adding
or removing of a virtual adapter. Anyone have an additional ides on
this?
- kumar
^ permalink raw reply [flat|nested] 5+ messages in thread
* [lm-sensors] I2C-virtual and locking?
2006-03-17 18:54 [lm-sensors] I2C-virtual and locking? Kumar Gala
@ 2006-03-17 21:16 ` Kumar Gala
0 siblings, 0 replies; 5+ messages in thread
From: Kumar Gala @ 2006-03-17 21:16 UTC (permalink / raw)
To: Greg KH, khali; +Cc: lm-sensors, linux kernel mailing list
On Mar 17, 2006, at 12:54 PM, Kumar Gala wrote:
> I'm looking at porting the i2c-virtual code from 2.4 to 2.6. One
> thing I'm not clear on is the use of i2c_add_adapter_nolock() by
> the old code. The only reference I can find related to this is:
>
> http://archives.andrew.net.au/lm-sensors/msg31060.html
>
> I can't think of a reason why locking would be in issue when adding
> or removing of a virtual adapter. Anyone have an additional ides
> on this?
Ok, so I figured out why the _nolock() versions exist. In
i2c_driver_register we take the core_list lock. Eventually we will
call i2c_probe() which should call driver->attach_adapter(). For a
virtual bus the driver's attach_adapter() will end up calling
i2c_virt_create_adapter() which will end up calling i2c_add_adapter()
which will never get the core_list lock.
So should we integrate the concept of virtual adapters into the i2c
core and have it such that i2c_virt_create_adapter()/
i2c_virt_remove_adapter() expects the caller to have the core_list
lock already?
- kumar
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: I2C-virtual and locking?
@ 2006-03-17 21:16 ` Kumar Gala
0 siblings, 0 replies; 5+ messages in thread
From: Kumar Gala @ 2006-03-17 21:16 UTC (permalink / raw)
To: Greg KH, khali; +Cc: lm-sensors, linux kernel mailing list
On Mar 17, 2006, at 12:54 PM, Kumar Gala wrote:
> I'm looking at porting the i2c-virtual code from 2.4 to 2.6. One
> thing I'm not clear on is the use of i2c_add_adapter_nolock() by
> the old code. The only reference I can find related to this is:
>
> http://archives.andrew.net.au/lm-sensors/msg31060.html
>
> I can't think of a reason why locking would be in issue when adding
> or removing of a virtual adapter. Anyone have an additional ides
> on this?
Ok, so I figured out why the _nolock() versions exist. In
i2c_driver_register we take the core_list lock. Eventually we will
call i2c_probe() which should call driver->attach_adapter(). For a
virtual bus the driver's attach_adapter() will end up calling
i2c_virt_create_adapter() which will end up calling i2c_add_adapter()
which will never get the core_list lock.
So should we integrate the concept of virtual adapters into the i2c
core and have it such that i2c_virt_create_adapter()/
i2c_virt_remove_adapter() expects the caller to have the core_list
lock already?
- kumar
^ permalink raw reply [flat|nested] 5+ messages in thread
* [lm-sensors] I2C-virtual and locking?
2006-03-17 21:16 ` Kumar Gala
@ 2006-03-17 23:08 ` Greg KH
-1 siblings, 0 replies; 5+ messages in thread
From: Greg KH @ 2006-03-17 23:08 UTC (permalink / raw)
To: Kumar Gala; +Cc: khali, lm-sensors, linux kernel mailing list
On Fri, Mar 17, 2006 at 03:16:58PM -0600, Kumar Gala wrote:
>
> On Mar 17, 2006, at 12:54 PM, Kumar Gala wrote:
>
> >I'm looking at porting the i2c-virtual code from 2.4 to 2.6. One
> >thing I'm not clear on is the use of i2c_add_adapter_nolock() by
> >the old code. The only reference I can find related to this is:
> >
> >http://archives.andrew.net.au/lm-sensors/msg31060.html
> >
> >I can't think of a reason why locking would be in issue when adding
> >or removing of a virtual adapter. Anyone have an additional ides
> >on this?
>
> Ok, so I figured out why the _nolock() versions exist. In
> i2c_driver_register we take the core_list lock. Eventually we will
> call i2c_probe() which should call driver->attach_adapter(). For a
> virtual bus the driver's attach_adapter() will end up calling
> i2c_virt_create_adapter() which will end up calling i2c_add_adapter()
> which will never get the core_list lock.
>
> So should we integrate the concept of virtual adapters into the i2c
> core and have it such that i2c_virt_create_adapter()/
> i2c_virt_remove_adapter() expects the caller to have the core_list
> lock already?
Possibly. Jean, what do you think?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: I2C-virtual and locking?
@ 2006-03-17 23:08 ` Greg KH
0 siblings, 0 replies; 5+ messages in thread
From: Greg KH @ 2006-03-17 23:08 UTC (permalink / raw)
To: Kumar Gala; +Cc: khali, lm-sensors, linux kernel mailing list
On Fri, Mar 17, 2006 at 03:16:58PM -0600, Kumar Gala wrote:
>
> On Mar 17, 2006, at 12:54 PM, Kumar Gala wrote:
>
> >I'm looking at porting the i2c-virtual code from 2.4 to 2.6. One
> >thing I'm not clear on is the use of i2c_add_adapter_nolock() by
> >the old code. The only reference I can find related to this is:
> >
> >http://archives.andrew.net.au/lm-sensors/msg31060.html
> >
> >I can't think of a reason why locking would be in issue when adding
> >or removing of a virtual adapter. Anyone have an additional ides
> >on this?
>
> Ok, so I figured out why the _nolock() versions exist. In
> i2c_driver_register we take the core_list lock. Eventually we will
> call i2c_probe() which should call driver->attach_adapter(). For a
> virtual bus the driver's attach_adapter() will end up calling
> i2c_virt_create_adapter() which will end up calling i2c_add_adapter()
> which will never get the core_list lock.
>
> So should we integrate the concept of virtual adapters into the i2c
> core and have it such that i2c_virt_create_adapter()/
> i2c_virt_remove_adapter() expects the caller to have the core_list
> lock already?
Possibly. Jean, what do you think?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2006-03-17 23:09 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-03-17 18:54 [lm-sensors] I2C-virtual and locking? Kumar Gala
2006-03-17 21:16 ` Kumar Gala
2006-03-17 21:16 ` Kumar Gala
2006-03-17 23:08 ` [lm-sensors] " Greg KH
2006-03-17 23:08 ` Greg KH
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