"Zhijian Li (Fujitsu)" <lizhij...@fujitsu.com> writes: > On 20/09/2023 21:01, Fabiano Rosas wrote: >> Li Zhijian <lizhij...@fujitsu.com> writes: >> >>> From: Li Zhijian <lizhij...@cn.fujitsu.com> >>> >>> Previously, we got a confusion error that complains >>> the RDMAControlHeader.repeat: >>> qemu-system-x86_64: rdma: Too many requests in this message >>> (3638950032).Bailing. >>> >>> Actually, it's caused by an unexpected RDMAControlHeader.type. >>> After this patch, error will become: >>> qemu-system-x86_64: Unknown control message QEMU FILE >>> >>> Signed-off-by: Li Zhijian <lizhij...@cn.fujitsu.com> >>> --- >>> migration/rdma.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/migration/rdma.c b/migration/rdma.c >>> index a2a3db35b1..3073d9953c 100644 >>> --- a/migration/rdma.c >>> +++ b/migration/rdma.c >>> @@ -2812,7 +2812,7 @@ static ssize_t qio_channel_rdma_writev(QIOChannel >>> *ioc, >>> size_t remaining = iov[i].iov_len; >>> uint8_t * data = (void *)iov[i].iov_base; >>> while (remaining) { >>> - RDMAControlHeader head; >>> + RDMAControlHeader head = {}; >>> >>> len = MIN(remaining, RDMA_SEND_INCREMENT); >>> remaining -= len; >> > > 2815 RDMAControlHeader head = {}; > 2816 > 2817 len = MIN(remaining, RDMA_SEND_INCREMENT); > 2818 remaining -= len; > 2819 > 2820 head.len = len; > 2821 head.type = RDMA_CONTROL_QEMU_FILE; > 2822 > 2823 ret = qemu_rdma_exchange_send(rdma, &head, data, NULL, NULL, > NULL); > >> I'm struggling to see how head is used before we set the type a couple >> of lines below. Could you expand on it? > > > IIUC, head is used for both common migration control path and RDMA specific > control path. > > hook_stage(RAM_SAVE_FLAG_HOOK) { > rdma_hook_process(qemu_rdma_registration_handle) { > do { > // this is a RDMA own control block, should not be disturbed by > the common migration control path. > // head will be extracted and processed here. > // qio_channel_rdma_writev() will send RDMA_CONTROL_QEMU_FILE, > which is an unexpected message for this block. > // head.repeat will be examined before the type, so an > uninitialized repeat will confuse us here. > } while (!RDMA_CONTROL_REGISTER_FINISHED || !error) > } > } > > > when qio_channel_rdma_writev() is used for common migration control path, > repeat is useless and will not be examined. > > With this patch, we can quickly know the cause. >
Ah, right. Somehow I interpreted the commit message as meaning the 'type' field was bogus. But it's the 'repeat' field that causes the issue. Thanks for the explanation. Reviewed-by: Fabiano Rosas <faro...@suse.de>