On Fri, May 3, 2013 at 5:35 PM, Stefan Hajnoczi <stefa...@gmail.com> wrote:
> On Fri, May 03, 2013 at 10:45:20AM +0800, Liu Ping Fan wrote:
>> From: Liu Ping Fan <pingf...@linux.vnet.ibm.com>
>>
>> With ref()/unref() interface of MemoryRegion, we can pin RAM-Device
>> when using its memory, and release it when done.
>>
>> Signed-off-by: Liu Ping Fan <pingf...@linux.vnet.ibm.com>
>> ---
>> hw/virtio/dataplane/hostmem.c | 44
>> +++++++++++++++++++++++++++-----
>> hw/virtio/dataplane/vring.c | 8 +++---
>> include/hw/virtio/dataplane/hostmem.h | 4 ++-
>> 3 files changed, 44 insertions(+), 12 deletions(-)
>>
>> diff --git a/hw/virtio/dataplane/hostmem.c b/hw/virtio/dataplane/hostmem.c
>> index 1fd3e06..0e28dfc 100644
>> --- a/hw/virtio/dataplane/hostmem.c
>> +++ b/hw/virtio/dataplane/hostmem.c
>> @@ -42,18 +42,28 @@ static void hostmem_ref(HostMem *hostmem)
>>
>> static void hostmem_unref(HostMem *hostmem)
>> {
>> - int t;
>> + int i, t;
>> + HostMemRegion *hmr;
>>
>> t = __sync_sub_and_fetch(&hostmem->ref, 1);
>> assert(t >= 0);
>> if (!t) {
>> + for (i = 0; i < hostmem->num_current_regions; i++) {
>> + hmr = &hostmem->current_regions[i];
>> + /* Fix me, when memory hotunplug implement
>> + * assert(hmr->mr_ops->unref)
>> + */
>> + if (hmr->mr->ops && hmr->mr->ops->unref) {
>> + hmr->mr->ops->unref();
>> + }
>
> This patch should use memory_region_ref()/unref() which you introduced
> in the previous patch instead of open-coding this.
>
Yes, reasonable.
>> @@ -158,6 +176,18 @@ static void
>> hostmem_listener_append_region(MemoryListener *listener,
>> hostmem_append_new_region(as_mem->next_hostmem, section);
>> }
>>
>> +static void hostmem_listener_append_region(MemoryListener *listener,
>> + MemoryRegionSection *section)
>> +{
>> + hostmem_listener_nop_region(listener, section);
>> + /* Fix me, when memory hotunplug implement
>> + * assert(section->mr->ops->ref)
>> + */
>> + if (section->mr->ops && section->mr->ops->ref) {
>> + section->mr->ops->ref();
>> + }
>> +}
>
> Why does append increment the refcount while nop does not?
>
> It seems that we always need to increment the memory region refcount
> since we're building a completely new hostmem. The refcount ownership
> is not passed from the current hostmen to the next hostmem, all memory
> regions are released in hostmem_unref().
Yes, you are right. Will fix it.
Thanks,
Pingfan
