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authorAlberto Garcia <berto@igalia.com>2015-06-08 18:17:45 +0200
committerStefan Hajnoczi <stefanha@redhat.com>2015-06-12 14:00:00 +0100
commitdb6283385cb708b9d589e5b57e96eab4afd0269e (patch)
tree4c50c7acecd3d79c6efb6beee4a359bfdb3322f1 /block.c
parent76f4afb40fa076ed23fe0ab42c7a768ddb71123f (diff)
downloadqemu-arm-db6283385cb708b9d589e5b57e96eab4afd0269e.tar.gz
throttle: acquire the ThrottleGroup lock in bdrv_swap()
bdrv_swap() touches the fields of a BlockDriverState that are protected by the ThrottleGroup lock. Although those fields end up in their original place, they are temporarily swapped in the process, so there's a chance that an operation on a member of the same group happening on a different thread can try to use them. Signed-off-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: d92dc40d7c4f1fc5cda5cbbf4ffb7a4670b79d17.1433779731.git.berto@igalia.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r--block.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/block.c b/block.c
index 1bc0e7394b..54d789a8e9 100644
--- a/block.c
+++ b/block.c
@@ -36,6 +36,7 @@
#include "qmp-commands.h"
#include "qemu/timer.h"
#include "qapi-event.h"
+#include "block/throttle-groups.h"
#ifdef CONFIG_BSD
#include <sys/types.h>
@@ -1887,11 +1888,20 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
QTAILQ_REMOVE(&graph_bdrv_states, bs_old, node_list);
}
+ /* If the BlockDriverState is part of a throttling group acquire
+ * its lock since we're going to mess with the protected fields.
+ * Otherwise there's no need to worry since no one else can touch
+ * them. */
+ if (bs_old->throttle_state) {
+ throttle_group_lock(bs_old);
+ }
+
/* bs_new must be unattached and shouldn't have anything fancy enabled */
assert(!bs_new->blk);
assert(QLIST_EMPTY(&bs_new->dirty_bitmaps));
assert(bs_new->job == NULL);
assert(bs_new->io_limits_enabled == false);
+ assert(bs_new->throttle_state == NULL);
assert(!throttle_timers_are_initialized(&bs_new->throttle_timers));
tmp = *bs_new;
@@ -1909,8 +1919,14 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
/* Check a few fields that should remain attached to the device */
assert(bs_new->job == NULL);
assert(bs_new->io_limits_enabled == false);
+ assert(bs_new->throttle_state == NULL);
assert(!throttle_timers_are_initialized(&bs_new->throttle_timers));
+ /* Release the ThrottleGroup lock */
+ if (bs_old->throttle_state) {
+ throttle_group_unlock(bs_old);
+ }
+
/* insert the nodes back into the graph node list if needed */
if (bs_new->node_name[0] != '\0') {
QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs_new, node_list);