On Fri, 11 Mar 2005 14:37:17 +1100, Peter Chubb
<[EMAIL PROTECTED]> wrote:
> + npages = get_user_pages(current,
> + current->mm,
> + (unsigned long)m.virtaddr,
> + maxpages,
> + write,
> + 0,
> + imp->pages,
> + NULL);
Can't comment on usermode drivers overall, so just some code comments.
do you need a down_read(current->mm->mmap_sem) here? I'm not sure but
that seems to be what most other users of this function are doing.
> + /*
> + * Build scatterlist, one entry per page.
> + * Allow for partial pages at start and end.
> + */
> + i = 1;
> + imp->sg[0].page = imp->pages[0];
> + imp->sg[0].offset = ((unsigned long)m.virtaddr) & (PAGE_SIZE - 1);
> + imp->sg[0].length = PAGE_SIZE - imp->sg[0].offset;
> + if (imp->sg[0].length >= m.size) {
> + imp->sg[0].length = m.size;
> + } else {
> + unsigned long len = m.size - imp->sg[0].length;
> + for (;len >= PAGE_SIZE && i < npages ; i++) {
> + imp->sg[i].page = imp->pages[i];
> + imp->sg[i].offset = 0;
> + imp->sg[i].length = PAGE_SIZE;
> + len -= PAGE_SIZE;
> + }
> + if (len) {
> + BUG_ON(i >= npages);
> + BUG_ON(len >= PAGE_SIZE);
> + imp->sg[i].page = imp->pages[i];
> + imp->sg[i].offset = 0;
> + imp->sg[i].length = len;
> + i++;
> + }
> + }
size_t len = m.size;
int offset = (unsigned long) m.virtaddr & ~PAGE_MASK;
for (i = 0; i < npages; i++)
{
imp->sg[i].page = imp->pages[i];
imp->sg[i].offset = offset;
imp->sg[i].length = min(len, PAGE_SIZE - offset);
offset = 0;
len -= imp->sg[i].length;
}
instead possibly?
Regards -- Andy
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
