> -----Original Message----- > From: Olivier Matz [mailto:olivier.matz at 6wind.com] > Sent: Tuesday, July 19, 2016 9:11 PM > To: Tan, Jianfeng; dev at dpdk.org; Xie, Huawei; yuanhan.liu at > linux.intel.com > Subject: Re: [PATCH] virtio: fix packet corruption > > 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.
Oh yes, gotcha. But if we do not set data_off properly, it's still buggy when others consume these mbufs, right? Thanks, Jianfeng > > 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
