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block/export: Fix vhost-user-blk shutdown with requests in flight

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The vhost-user-blk export runs requests asynchronously in their own
coroutine. When the vhost connection goes away and we want to stop the
vhost-user server, we need to wait for these coroutines to stop before
we can unmap the shared memory. Otherwise, they would still access the
unmapped memory and crash.

This introduces a refcount to VuServer which is increased when spawning
a new request coroutine and decreased before the coroutine exits. The
memory is only unmapped when the refcount reaches zero.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20220125151435.48792-1-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2022-01-25 16:14:35 +01:00
parent c0829cb1fd
commit 520d8b40e8
3 changed files with 32 additions and 0 deletions
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5
block/export/vhost-user-blk-server.c
View file

@ -172,6 +172,7 @@ vu_blk_discard_write_zeroes(VuBlkExport *vexp, struct iovec *iov,
return VIRTIO_BLK_S_IOERR;
}
/* Called with server refcount increased, must decrease before returning */
static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
{
VuBlkReq *req = opaque;
@ -286,10 +287,12 @@ static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
}
vu_blk_req_complete(req);
vhost_user_server_unref(server);
return;
err:
free(req);
vhost_user_server_unref(server);
}
static void vu_blk_process_vq(VuDev *vu_dev, int idx)
@ -310,6 +313,8 @@ static void vu_blk_process_vq(VuDev *vu_dev, int idx)
Coroutine *co =
qemu_coroutine_create(vu_blk_virtio_process_req, req);
vhost_user_server_ref(server);
qemu_coroutine_enter(co);
}
}