Hi Jianfeng, On 07/19/2016 03:03 PM, Tan, Jianfeng wrote: > Hi Oliver, > >> -----Original Message----- >> From: Olivier Matz [mailto:olivier.matz at 6wind.com] >> Sent: Tuesday, July 19, 2016 8:32 PM >> To: dev at dpdk.org; Tan, Jianfeng; Xie, Huawei; yuanhan.liu at >> linux.intel.com >> Subject: [PATCH] virtio: fix packet corruption >> >> The support of virtio-user changed the way the mbuf dma address is >> retrieved, using a physical address in case of virtio-pci and a virtual >> address in case of virtio-user. >> >> This change introduced some possible memory corruption in packets, >> replacing: >> m->buf_physaddr + RTE_PKTMBUF_HEADROOM >> by: >> m->buf_physaddr + m->data_off (through a macro) >> >> This patch fixes this issue, restoring the original behavior. > > Could you be more specific on why we cannot use m->data_off here?
There is no guarantee that m->data_off == RTE_PKTMBUF_HEADROOM here as virtqueue_enqueue_recv_refill() is called on a mbuf that is just allocated with rte_mbuf_raw_alloc(). An alternative would be to set data_off to RTE_PKTMBUF_HEADROOM, but as it's a fix and we are close to the release, I prefered to restore the initial behavior. I did not include the test plan because it relies on patch that are not submitted yet (offload patches, they will be upstreamed very soon). It is a quite simple test case with testpmd. Regards, Olivier