On Thu, Oct 08, 2015 at 12:45:08PM +0300, Gleb Natapov wrote: > On Thu, Oct 08, 2015 at 12:38:28PM +0300, Michael S. Tsirkin wrote: > > On Thu, Oct 08, 2015 at 10:59:10AM +0300, Gleb Natapov wrote: > > > I do not remember this been an issue when uio_generic was accepted > > > into the kernel. The reason was because it meant to be accessible by root > > > only. > > > > No - because it does not need bus mastering. So it can be used safely > > with some devices. > > > It still can be used safely with same devices.
This patch does not add any functionality that can be used safely. And for no good reason except it's a hassle. > Admittedly I did not look > close, but I am sure the patch does not enable bus mastering if MSI > interrupt is not requested. If not, well that can be fixed. But more > importantly it can be used unsafely in its current state. Not only can, > it is widely used so. > > > [mst@robin linux]$ git grep pci_set_master|wc -l 533 > > [mst@robin linux]$ git grep pci_enable|wc -l 1597 > > > > Looks like about 2/3 devices don't need to be bus masters. > > > > It's up to admin not to bind it to devices, and that is unfortunate, > > but manually binding an incorrect driver to a device is generally > > a hard problem to solve. > > > > > > There's also drivers/vfio/virqfd.c which deals > > > > with sending interrupts over eventfds correctly. > > > > > > > As opposite to this patch that deals with them incorrectly? In what way? > > > > cleanup on fd close is not handled. > > > Have you commented about this on the patch and it was not fixed? No - I only noticed this when I poked at VFIO to try and explain why it's not a good idea to duplicate its code. I'm sure there are more issues that we'll just have to re-discover the hard way if we do try. > -- > Gleb. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
