On Wed, Oct 14, 2015 at 10:50:40PM +0800, Xiao Guangrong wrote:
> On 10/14/2015 05:40 PM, Stefan Hajnoczi wrote:
> >On Sun, Oct 11, 2015 at 11:52:59AM +0800, Xiao Guangrong wrote:
> >> static void dsm_write(void *opaque, hwaddr addr,
> >> uint64_t val, unsigned size)
> >> {
> >>+ NVDIMMState *state = opaque;
> >>+ MemoryRegion *dsm_ram_mr;
> >>+ dsm_in *in;
> >>+ dsm_out *out;
> >>+ uint32_t revision, function, handle;
> >>+
> >> if (val != NOTIFY_VALUE) {
> >> fprintf(stderr, "BUG: unexepected notify value 0x%" PRIx64, val);
> >> }
> >>+
> >>+ dsm_ram_mr = memory_region_find(&state->mr, state->page_size,
> >>+ state->page_size).mr;
> >>+ memory_region_unref(dsm_ram_mr);
> >>+ in = memory_region_get_ram_ptr(dsm_ram_mr);
> >
> >This looks suspicious. Shouldn't the memory_region_unref(dsm_ram_mr)
> >happen after we're done using it?
>
> This region is keep-alive during QEMU's running, it is okay. The same
> style is applied to other codes, for example: line 208 in
> hw/s390x/sclp.c.
In sclp.c (assign_storage()), the memory region is never used after
memory_region_unref() is called. In unassign_storage(), sclp.c owns an
additional reference, grabbed by assign_storage().
--
Eduardo
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