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author | Maxim Levitsky <mlevitsk@redhat.com> | 2020-10-06 15:38:59 +0300 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-10-12 11:50:50 -0400 |
commit | 2d24a64661549732fc77f632928318dd52f5bce5 (patch) | |
tree | 3e7f20a87ef9c2368db3f988fe331279cacf236a /include | |
parent | 7bed89958bfbf40df9ca681cefbdca63abdde39d (diff) | |
download | qemu-2d24a64661549732fc77f632928318dd52f5bce5.zip qemu-2d24a64661549732fc77f632928318dd52f5bce5.tar.gz qemu-2d24a64661549732fc77f632928318dd52f5bce5.tar.bz2 |
device-core: use RCU for list of children of a bus
This fixes the race between device emulation code that tries to find
a child device to dispatch the request to (e.g a scsi disk),
and hotplug of a new device to that bus.
Note that this doesn't convert all the readers of the list
but only these that might go over that list without BQL held.
This is a very small first step to make this code thread safe.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200913160259.32145-5-mlevitsk@redhat.com>
[Use RCU_READ_LOCK_GUARD in more places, adjust testcase now that
the delay in DEVICE_DELETED due to RCU is more consistent. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20201006123904.610658-9-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include')
-rw-r--r-- | include/hw/qdev-core.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h index 14d476c..2c6307e 100644 --- a/include/hw/qdev-core.h +++ b/include/hw/qdev-core.h @@ -3,6 +3,8 @@ #include "qemu/queue.h" #include "qemu/bitmap.h" +#include "qemu/rcu.h" +#include "qemu/rcu_queue.h" #include "qom/object.h" #include "hw/hotplug.h" #include "hw/resettable.h" @@ -238,6 +240,7 @@ struct BusClass { }; typedef struct BusChild { + struct rcu_head rcu; DeviceState *child; int index; QTAILQ_ENTRY(BusChild) sibling; @@ -258,6 +261,12 @@ struct BusState { int max_index; bool realized; int num_children; + + /* + * children is a RCU QTAILQ, thus readers must use RCU to access it, + * and writers must hold the big qemu lock + */ + QTAILQ_HEAD(, BusChild) children; QLIST_ENTRY(BusState) sibling; ResettableState reset; |