Yes, this *is* wrong.
> My question is: Can I detect at which point application unmap memory
> area? Is there any callback for it or some like this?
There are the "virtual memory operations", that are meant just for that
purpose: give a driver some control over its memory mapped regions.
You can implement a usage count in virtual memory areas with code like
this one:
static struct vm_operations_struct simple_vm_ops = {
simple_vma_open,
simple_vma_close, /* no more fields */
};
void simple_vma_open(struct vm_area_struct * area)
{ MOD_INC_USE_COUNT; }
void simple_vma_close(struct vm_area_struct * area)
{ MOD_DEC_USE_COUNT; }
int simple_mmap(struct inode *inode, struct file *filp,
struct vm_area_struct *vma)
{
/* int remap_page_range(virt_add, phys_add, size, protection); */
if (remap_page_range(vma->vm_start, vma->vm_offset,
vma->vm_end-vma->vm_start, vma->vm_page_prot))
return -EAGAIN;
if (vma->vm_ops)
return -EINVAL; /* Hmm... shouldn't happen */
vma->vm_ops = &simple_vm_ops;
MOD_INC_USE_COUNT; /* open(vma) wasn't called this time */
vma->vm_inode = inode;
inode->i_count++;
return 0;
}
Best
/alessandro
--
__ o Tu vuo` fa` l'americano: sient'a me chi t'o fa fa`.
_`\<, (Renato Carosone)
__( )/( )__ alessandro.rubini@linux.it +39-382-529554
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