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[Qemu-devel] [PULL 14/39] qom/object: update class cache atomically
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 14/39] qom/object: update class cache atomically |
Date: |
Fri, 7 Oct 2016 18:57:38 +0200 |
From: Alex Bennée <address@hidden>
The idiom CPU_GET_CLASS(cpu) is fairly extensively used in various
threads and trips of ThreadSanitizer due to the fact it updates
obj->class->object_cast_cache behind the scenes. As this is just a
fast-path cache there is no need to lock updates.
However to ensure defined C11 behaviour across threads we need to use
the plain atomic_read/set primitives and keep the sanitizer happy.
Signed-off-by: Alex Bennée <address@hidden>
Reviewed-by: Marc-André Lureau <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
qom/object.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/qom/object.c b/qom/object.c
index 8166b7d..7a05e35 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -614,7 +614,7 @@ Object *object_dynamic_cast_assert(Object *obj, const char
*typename,
Object *inst;
for (i = 0; obj && i < OBJECT_CLASS_CAST_CACHE; i++) {
- if (obj->class->object_cast_cache[i] == typename) {
+ if (atomic_read(&obj->class->object_cast_cache[i]) == typename) {
goto out;
}
}
@@ -631,10 +631,10 @@ Object *object_dynamic_cast_assert(Object *obj, const
char *typename,
if (obj && obj == inst) {
for (i = 1; i < OBJECT_CLASS_CAST_CACHE; i++) {
- obj->class->object_cast_cache[i - 1] =
- obj->class->object_cast_cache[i];
+ atomic_set(&obj->class->object_cast_cache[i - 1],
+ atomic_read(&obj->class->object_cast_cache[i]));
}
- obj->class->object_cast_cache[i - 1] = typename;
+ atomic_set(&obj->class->object_cast_cache[i - 1], typename);
}
out:
@@ -704,7 +704,7 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass
*class,
int i;
for (i = 0; class && i < OBJECT_CLASS_CAST_CACHE; i++) {
- if (class->class_cast_cache[i] == typename) {
+ if (atomic_read(&class->class_cast_cache[i]) == typename) {
ret = class;
goto out;
}
@@ -725,9 +725,10 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass
*class,
#ifdef CONFIG_QOM_CAST_DEBUG
if (class && ret == class) {
for (i = 1; i < OBJECT_CLASS_CAST_CACHE; i++) {
- class->class_cast_cache[i - 1] = class->class_cast_cache[i];
+ atomic_set(&class->class_cast_cache[i - 1],
+ atomic_read(&class->class_cast_cache[i]));
}
- class->class_cast_cache[i - 1] = typename;
+ atomic_set(&class->class_cast_cache[i - 1], typename);
}
out:
#endif
--
2.7.4
- [Qemu-devel] [PULL 04/39] intc: add an interface to gather statistics/informations on interrupt controllers, (continued)
- [Qemu-devel] [PULL 04/39] intc: add an interface to gather statistics/informations on interrupt controllers, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 05/39] intc/i8259: implement InterruptStatsProvider interface, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 06/39] intc/slavio_intctl: implement InterruptStatsProvider interface, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 07/39] intc/lm32_pic: implement InterruptStatsProvider interface, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 08/39] intc: make HMP 'info irq' and 'info pic' commands use InterruptStatsProvider interface, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 09/39] intc: make HMP 'info irq' and 'info pic' commands available on all targets, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 10/39] atomic.h: fix __SANITIZE_THREAD__ build, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 11/39] atomic.h: comment on use of atomic_read/set, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 12/39] tcg/optimize: move default return out of if statement, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 13/39] seqlock: use atomic writes for the sequence, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 14/39] qom/object: update class cache atomically,
Paolo Bonzini <=
- [Qemu-devel] [PULL 15/39] qom/cpu: atomically clear the tb_jmp_cache, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 16/39] cpu: atomically modify cpu->exit_request, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 17/39] util/qht: atomically set b->hashes, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 18/39] linux-user/syscall: extend lock around cpu-list, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 19/39] qga/command: use QEMU atomic primitives, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 20/39] .travis.yml: add gcc sanitizer build, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 22/39] char: use a fixed idx for child muxed chr, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 21/39] i8259: give ISA device when registering ISA ioports, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 23/39] char: update read handler in all cases, Paolo Bonzini, 2016/10/07
- [Qemu-devel] [PULL 25/39] qemu_kill_report: Report PID name too, Paolo Bonzini, 2016/10/07