On Tue, Apr 16, 2019 at 10:37:07AM +0100, Ferruh Yigit wrote: > On 4/12/2019 11:08 PM, Stephen Hemminger wrote: > > On Fri, 12 Apr 2019 17:28:17 +0100 > > Ferruh Yigit <ferruh.yi...@intel.com> wrote: > > > >> On 4/8/2019 5:41 PM, Stephen Hemminger wrote: > >>> If the af_packet transmit is sending a VLAN packet, > >>> and the transmit path to the kernel os full, then it would > >>> mismanage the outgoing mbuf. The original mbuf would end up > >>> being freed twice, once by AF_PACKET PMD and once by caller. > >> > >> This comment is valid with your new patch [1] that updates > >> 'rte_vlan_insert()' > >> to duplicate the mbuf, right? > >> > >> That patch looks like won't make the release, so I suggest this one wait > >> that > >> patch, although this is harmless on its own, commit log is misleading. > >> > >> [1] > >> https://patches.dpdk.org/patch/51870/ > > > > It was always true, even with existing vlan_insert. > > Existing vlan_insert has issues if it ever creates a clone packet. > > Existing vlan_insert can duplicate mbuf through clone > > > > Right, existing vlan_insert has same issue on af_packet. > > But, should vlan_insert try to duplicate the mbuf when it is shared, does it > worth the complexity it brings? And when that support removed this patch won't > be needed.
I don't think vlan insert or other mbuf manipulation APIs should be checking for shared state or not - that's the job of the app. We could have cases where the user does want to modify a shared mbuf. Regards, /Bruce
