Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
dma-helpers.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/dma-helpers.c b/dma-helpers.c
index 68f6f07..b3e19ba 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -210,9 +210,25 @@ BlockAIOCB *dma_blk_io(
dbs->sg_cur_byte = 0;
dbs->dir = dir;
dbs->io_func = io_func;
- dbs->bh = NULL;
qemu_iovec_init(&dbs->iov, sg->nsg);
- dma_blk_cb(dbs, 0);
+
+ /* FIXME: dma_blk_io usually is called while the thread has acquired the
+ * AioContext, for consistency with blk_aio_readv. However, dma_memory_map
+ * may acquire the iothread lock and thus requires being called with _no_
lock.
+ *
+ * The solution would be to call dma_blk_io without the AioContext lock,
+ * but this requires changes in the core block and SCSI layers. In the
+ * interest of doing things a step at a time, defer to a bottom half
+ * if the iothread lock isn't taken. The bottom half is called without
+ * the AioContext lock taken.
+ */
+ if (qemu_mutex_iothread_locked()) {
+ dbs->bh = NULL;
+ dma_blk_cb(dbs, 0);
+ } else {
+ dbs->bh = aio_bh_new(dbs->ctx, reschedule_dma, dbs);
+ qemu_bh_schedule(dbs->bh);
+ }
return &dbs->common;
}
--
1.8.3.1
