Messages in this thread | | | Date | Thu, 16 Mar 2006 17:46:53 +0000 (GMT) | From | Hugh Dickins <> | Subject | Re: [PATCH 10 of 20] ipath - support for userspace apps using core driver |
| |
On Thu, 16 Mar 2006, Bryan O'Sullivan wrote: > On Wed, 2006-03-15 at 21:54 -0800, Roland Dreier wrote: > > > How about the case where one wants to map pages from > > dma_alloc_coherent() into userspace? > > This is precisely our case, btw. The pages in question are allocated > during fops->open (some during dev->probe). mmap and nopage never > allocate anything. > > > It seems one should do > > get_page() in .nopage, and then the driver can do dma_free_coherent() > > when the vma is released. > > If that were the case, I'm unclear on how I would do this. Add a > vmops->close method along with the existing vmops->nopage handler?
If neither mmap nor nopage allocated something, then vmops->close would be the wrong point at which to free it, I think.
If dev->probe allocated something, module unload would be the right point to free it. If fops->open allocated something, fops->release would be the right point to free it.
I think. Beware, I've never written a Linux driver, and may well have this wrong or oversimplified: in which case, I'll have annoyed someone enough for them to correct me very soon.
Hugh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |