[openib-general][PATCH][kdapl]: inc/dec module ref count

[James Lentini]

On Sun, 31 Jul 2005, Muli Ben-Yehuda wrote:

> On Sun, Jul 31, 2005 at 06:08:11PM +0300, Guy German wrote:
>> Hi Muli,
>>
>> Wouldn't it be solved by moving the try_module_get call to the
>> beginning of the dapl_ia_open function ?
>
> No. Even if it's theoretically the first line in the function, the
> compiler can and will create a function prologue that will run before
> you raise the reference count (same thing with decrementing the ref
> count at module unload time and the function epilogue). You must do
> module reference counting before executing even one instruction from
> the module.
>
>> You are right - try_module_get() can fail when the module is not ready
>> to be entered. should be something like:
>> + if (!try_module_get(THIS_MODULE))
>> +	return -EBUSY;
>
> Yes - but at the caller, not callee.

Putting this in the caller (i.e. dat_ia_open and dat_ia_close) does 
sound like a better option.

Guy, can you investigate why the ib_mthca module doesn't have a 
reference count and see if it relates to hotplug? I think kdapl_ib and 
ib_mthca should have the same policy regarding this issue.