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author | Peter Maydell <peter.maydell@linaro.org> | 2015-02-02 19:36:02 +0000 |
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committer | Peter Maydell <peter.maydell@linaro.org> | 2015-02-02 19:36:02 +0000 |
commit | d5fbb4c9ed52d97aebe5994d8a857c74c0d95a92 (patch) | |
tree | 46ddd11a5abcfaa68db676948ecf83303d153cfd /memory.c | |
parent | 16017c48547960539fcadb1f91d252124f442482 (diff) | |
parent | 2aeba9d8a1b6121b98948fcd42fd2aa32f68b750 (diff) | |
download | hqemu-d5fbb4c9ed52d97aebe5994d8a857c74c0d95a92.zip hqemu-d5fbb4c9ed52d97aebe5994d8a857c74c0d95a92.tar.gz |
Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging
The important bits here are the first part of RCU.
v1->v2 changes are the new qemu-thread patch to fix Mac OS X,
and cleaning up warnings.
v2->v3 removed the patch to enable modules by default.
# gpg: Signature made Mon 02 Feb 2015 19:28:03 GMT using RSA key ID 78C7AE83
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>"
# gpg: aka "Paolo Bonzini <pbonzini@redhat.com>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg: It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4 E2F7 7E15 100C CD36 69B1
# Subkey fingerprint: F133 3857 4B66 2389 866C 7682 BFFB D25F 78C7 AE83
* remotes/bonzini/tags/for-upstream:
scsi: Fix scsi_req_cancel_async for no aiocb req
cpu-exec: simplify init_delay_params
cpu-exec: simplify align_clocks
memory: avoid ref/unref in memory_region_find
memory: protect current_map by RCU
memory: remove assertion on memory_region_destroy
rcu: add call_rcu
rcu: allow nesting of rcu_read_lock/rcu_read_unlock
rcu: add rcutorture
rcu: add rcu library
qemu-thread: fix qemu_event without futexes
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'memory.c')
-rw-r--r-- | memory.c | 65 |
1 files changed, 28 insertions, 37 deletions
@@ -33,26 +33,12 @@ static bool memory_region_update_pending; static bool ioeventfd_update_pending; static bool global_dirty_log = false; -/* flat_view_mutex is taken around reading as->current_map; the critical - * section is extremely short, so I'm using a single mutex for every AS. - * We could also RCU for the read-side. - * - * The BQL is taken around transaction commits, hence both locks are taken - * while writing to as->current_map (with the BQL taken outside). - */ -static QemuMutex flat_view_mutex; - static QTAILQ_HEAD(memory_listeners, MemoryListener) memory_listeners = QTAILQ_HEAD_INITIALIZER(memory_listeners); static QTAILQ_HEAD(, AddressSpace) address_spaces = QTAILQ_HEAD_INITIALIZER(address_spaces); -static void memory_init(void) -{ - qemu_mutex_init(&flat_view_mutex); -} - typedef struct AddrRange AddrRange; /* @@ -242,6 +228,7 @@ struct FlatRange { * order. */ struct FlatView { + struct rcu_head rcu; unsigned ref; FlatRange *ranges; unsigned nr; @@ -654,10 +641,10 @@ static FlatView *address_space_get_flatview(AddressSpace *as) { FlatView *view; - qemu_mutex_lock(&flat_view_mutex); - view = as->current_map; + rcu_read_lock(); + view = atomic_rcu_read(&as->current_map); flatview_ref(view); - qemu_mutex_unlock(&flat_view_mutex); + rcu_read_unlock(); return view; } @@ -766,10 +753,9 @@ static void address_space_update_topology(AddressSpace *as) address_space_update_topology_pass(as, old_view, new_view, false); address_space_update_topology_pass(as, old_view, new_view, true); - qemu_mutex_lock(&flat_view_mutex); - flatview_unref(as->current_map); - as->current_map = new_view; - qemu_mutex_unlock(&flat_view_mutex); + /* Writes are protected by the BQL. */ + atomic_rcu_set(&as->current_map, new_view); + call_rcu(old_view, flatview_unref, rcu); /* Note that all the old MemoryRegions are still alive up to this * point. This relieves most MemoryListeners from the need to @@ -1263,7 +1249,6 @@ static void memory_region_finalize(Object *obj) MemoryRegion *mr = MEMORY_REGION(obj); assert(QTAILQ_EMPTY(&mr->subregions)); - assert(memory_region_transaction_depth == 0); mr->destructor(mr); memory_region_clear_coalescing(mr); g_free((char *)mr->name); @@ -1843,11 +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)) { @@ -1864,8 +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; } @@ -1958,10 +1943,6 @@ void memory_listener_unregister(MemoryListener *listener) void address_space_init(AddressSpace *as, MemoryRegion *root, const char *name) { - if (QTAILQ_EMPTY(&address_spaces)) { - memory_init(); - } - memory_region_transaction_begin(); as->root = root; as->current_map = g_new(FlatView, 1); @@ -1975,15 +1956,10 @@ void address_space_init(AddressSpace *as, MemoryRegion *root, const char *name) memory_region_transaction_commit(); } -void address_space_destroy(AddressSpace *as) +static void do_address_space_destroy(AddressSpace *as) { MemoryListener *listener; - /* Flush out anything from MemoryListeners listening in on this */ - memory_region_transaction_begin(); - as->root = NULL; - memory_region_transaction_commit(); - QTAILQ_REMOVE(&address_spaces, as, address_spaces_link); address_space_destroy_dispatch(as); QTAILQ_FOREACH(listener, &memory_listeners, link) { @@ -1995,6 +1971,21 @@ void address_space_destroy(AddressSpace *as) g_free(as->ioeventfds); } +void address_space_destroy(AddressSpace *as) +{ + /* Flush out anything from MemoryListeners listening in on this */ + memory_region_transaction_begin(); + as->root = NULL; + memory_region_transaction_commit(); + QTAILQ_REMOVE(&address_spaces, as, address_spaces_link); + + /* At this point, as->dispatch and as->current_map are dummy + * entries that the guest should never use. Wait for the old + * values to expire before freeing the data. + */ + call_rcu(as, do_address_space_destroy, rcu); +} + bool io_mem_read(MemoryRegion *mr, hwaddr addr, uint64_t *pval, unsigned size) { return memory_region_dispatch_read(mr, addr, pval, size); |