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[Qemu-devel] [PULL 07/11] memory: avoid ref/unref in memory_region_find
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 07/11] memory: avoid ref/unref in memory_region_find |
Date: |
Fri, 30 Jan 2015 16:19:53 +0100 |
Do the entire lookup under RCU, which avoids atomic operations
in flatview_ref and flatview_unref.
Reviewed-by: Fam Zheng <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
memory.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/memory.c b/memory.c
index a844ced..9b91243 100644
--- a/memory.c
+++ b/memory.c
@@ -1828,11 +1828,11 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr,
}
range = addrrange_make(int128_make64(addr), int128_make64(size));
- view = address_space_get_flatview(as);
+ rcu_read_lock();
+ view = atomic_rcu_read(&as->current_map);
fr = flatview_lookup(view, range);
if (!fr) {
- flatview_unref(view);
- return ret;
+ goto out;
}
while (fr > view->ranges && addrrange_intersects(fr[-1].addr, range)) {
@@ -1849,8 +1849,8 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr,
ret.offset_within_address_space = int128_get64(range.start);
ret.readonly = fr->readonly;
memory_region_ref(ret.mr);
-
- flatview_unref(view);
+out:
+ rcu_read_unlock();
return ret;
}
--
1.8.3.1
- [Qemu-devel] [PULL 04/11] rcu: add call_rcu, (continued)
- [Qemu-devel] [PULL 04/11] rcu: add call_rcu, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 09/11] cpu-exec: simplify init_delay_params, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 07/11] memory: avoid ref/unref in memory_region_find, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 11/11] configure: Default to enable module build, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 10/11] scsi: Fix scsi_req_cancel_async for no aiocb req, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 00/11] RCU, scsi, modules, icount changes for 2015-01-30, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 02/11] rcu: add rcutorture, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 01/11] rcu: add rcu library, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 04/11] rcu: add call_rcu, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 06/11] memory: protect current_map by RCU, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 07/11] memory: avoid ref/unref in memory_region_find,
Paolo Bonzini <=
- [Qemu-devel] [PULL 03/11] rcu: allow nesting of rcu_read_lock/rcu_read_unlock, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 08/11] cpu-exec: simplify align_clocks, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 05/11] memory: remove assertion on memory_region_destroy, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 10/11] scsi: Fix scsi_req_cancel_async for no aiocb req, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 09/11] cpu-exec: simplify init_delay_params, Paolo Bonzini, 2015/01/30
- [Qemu-devel] [PULL 11/11] configure: Default to enable module build, Paolo Bonzini, 2015/01/30