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authorStefan Hajnoczi <stefanha@redhat.com>2018-03-07 14:42:02 +0000
committerStefan Hajnoczi <stefanha@redhat.com>2018-03-08 17:38:51 +0000
commitb89d92f3cfc0f6e6d05e146e7a5fb8c759978051 (patch)
tree36927b2b1c7f082a20f890ee7e4d5b0b84ce6f90 /util
parent12c1c7d7cefb4dbffeb5712e75a33e4692f0a76b (diff)
block: add aio_wait_bh_oneshot()
Sometimes it's necessary for the main loop thread to run a BH in an IOThread and wait for its completion. This primitive is useful during startup/shutdown to synchronize and avoid race conditions. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20180307144205.20619-2-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'util')
-rw-r--r--util/aio-wait.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/util/aio-wait.c b/util/aio-wait.c
index a487cdb852..975afddf4c 100644
--- a/util/aio-wait.c
+++ b/util/aio-wait.c
@@ -38,3 +38,34 @@ void aio_wait_kick(AioWait *wait)
aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL);
}
}
+
+typedef struct {
+ AioWait wait;
+ bool done;
+ QEMUBHFunc *cb;
+ void *opaque;
+} AioWaitBHData;
+
+/* Context: BH in IOThread */
+static void aio_wait_bh(void *opaque)
+{
+ AioWaitBHData *data = opaque;
+
+ data->cb(data->opaque);
+
+ data->done = true;
+ aio_wait_kick(&data->wait);
+}
+
+void aio_wait_bh_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
+{
+ AioWaitBHData data = {
+ .cb = cb,
+ .opaque = opaque,
+ };
+
+ assert(qemu_get_current_aio_context() == qemu_get_aio_context());
+
+ aio_bh_schedule_oneshot(ctx, aio_wait_bh, &data);
+ AIO_WAIT_WHILE(&data.wait, ctx, !data.done);
+}