Messages in this thread | | | Date | Mon, 29 Jun 2009 12:44:53 +0300 | From | Avi Kivity <> | Subject | Re: [PATCHv2] kvm: remove in_range and switch to rwsem for iobus |
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On 06/29/2009 12:23 PM, Michael S. Tsirkin wrote: > 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). >> >> 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. >> > > IMO this will make it harder to convert to rcu down the line. > As it is we just grep for bus_lock and replace with rcu. > While possibly slots_lock can be converted to rcu as well, > let's do it one thing at a time. >
We can convert it to rcu indepenently of other things protected by slots_lock; no need to do everything at the same time.
-- error compiling committee.c: too many arguments to function
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