From: Christian Schoenebeck <[email protected]> Add and implement the response_buffer_size callback for the Xen transport.
Returns the size of the response buffer from the rings in_sg, as limit for 9p server while generating a response for supplied PDU. We use a local iovec array variable in_sg[2] instead of ring->sg, as ring->sg is only allocated by init_in_iov_from_pdu() and init_out_iov_from_pdu() during request / response processing. response_buffer_size() however may be called before those allocators, which would dereference ring->sg as NULL pointer. The local array avoids this. Reviewed-by: Stefano Stabellini <[email protected]> Link: https://lore.kernel.org/qemu-devel/3b139769eb1d3f9d91ee5281228e6467f9a08b99.1781287774.git.qemu_...@crudebyte.com Signed-off-by: Christian Schoenebeck <[email protected]> (cherry picked from commit 69c8f5e6946f76a70b141a340c7aeb9d6a8e3c27) Signed-off-by: Michael Tokarev <[email protected]> diff --git a/hw/9pfs/xen-9p-backend.c b/hw/9pfs/xen-9p-backend.c index e31124bcf51..24c90d97ec9 100644 --- a/hw/9pfs/xen-9p-backend.c +++ b/hw/9pfs/xen-9p-backend.c @@ -268,6 +268,17 @@ static size_t xen_9p_msize_limit(V9fsState *s) return limit; } +static size_t xen_9pfs_response_buffer_size(V9fsPDU *pdu) +{ + Xen9pfsDev *priv = container_of(pdu->s, Xen9pfsDev, state); + Xen9pfsRing *ring = &priv->rings[pdu->tag % priv->num_rings]; + struct iovec in_sg[2]; + int num; + + xen_9pfs_in_sg(ring, in_sg, &num, pdu->idx, 0); + return iov_size(in_sg, num); +} + static const V9fsTransport xen_9p_transport = { .pdu_vmarshal = xen_9pfs_pdu_vmarshal, .pdu_vunmarshal = xen_9pfs_pdu_vunmarshal, @@ -275,6 +286,7 @@ static const V9fsTransport xen_9p_transport = { .init_out_iov_from_pdu = xen_9pfs_init_out_iov_from_pdu, .push_and_notify = xen_9pfs_push_and_notify, .msize_limit = xen_9p_msize_limit, + .response_buffer_size = xen_9pfs_response_buffer_size, }; static int xen_9pfs_init(struct XenLegacyDevice *xendev) -- 2.47.3
