softirq argument

Hi all
As an experiment, i am trying to use softirq instead of using tasklet
in my driver code.
I was passing the driver's structure pointer to the tasklet.
The "open_softirq" takes only the function pointer as argument.
Since we can't pass any argument to the softirq, is there any
workaround that is possible to make the structure pointer accessible
to softirq?
I just need to do this for taking measurements.
Thanks,
mugunthan