Hi Mark
> I've been looking through some of the device drivers and find quite often a
> call
> to request_region of the form:
>
> if (!request_region(IO_INDEX_PORT, 2, WATCHDOG_NAME))
> {
> printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
> IO_INDEX_PORT);
> rc = -EIO;
> goto err_out;
> }
>
> I was interested in finding out what happens to the pointer which is returned
> from request_region. This if statement simply interests itself with the case
> of
> request_region returning NULL and makes no consideration that a pointer
> may be returned.
The point is that with "request_region" the region you requested is internally
inserted in a linked list. So you are not supposed to free the memory,
unless it is removed again from that list. And this is done by the
"release_region" macro implicitly (removed from the list and the memory
released).
Hope this makes it a bit clearer.
Arvin
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