On Mon, Jun 29, 2009 at 11:37:00AM +0300, Avi Kivity wrote: > On 06/28/2009 10:34 PM, Michael S. Tsirkin wrote: >> This changes bus accesses to use high-level kvm_io_bus_read/kvm_io_bus_write >> functions, which utilize read/write semaphore intead of mutex. in_range now >> becomes unused so it is removed from device ops in favor of read/write >> callbacks performing range checks internally. >> >> This allows aliasing (mostly for in-kernel virtio), as well as better error >> handling by making it possible to pass errors up to userspace. And it's enough >> to look at the diffstat to see that it's a better API anyway. >> >> While we are at it, document locking rules for kvm_io_device_ops. >> >> Note: since the use of the new bus_lock is localized to a small number of >> places, it will be easy to switch to srcu in the future if we so desire. >> > > Looks good. But please split into a locking change patch and an API > change patch (in whatever order makes more sense). This is harder than it seems. Is this really important? The locking change itself is about 6 lines, but 1. if I do it after in_range removal I get deadlocks as after marcelo's change kvm->lock is taken internally by writers. 2. if I do it before in_range removal it's a lot of churn: one of the reasons for code reorg is so that there are less places to change locking. > I think you can reuse slots_lock instead of adding a new lock. IIRC > slots_lock is already taken for read everywhere, so you only need to > take it for write when registering things. > > -- > error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
