On Sat, 11 May 2019 at 23:16, Vladimir Oltean <olte...@gmail.com> wrote: > > Making DSA use the sk_buff control block was my idea during the > 'Traffic-support-for-SJA1105-DSA-driver' patchset, and I had also > introduced a series of macro helpers that turned out to not be so > helpful: > > 1. DSA_SKB_ZERO() zeroizes the 48-byte skb->cb area, but due to the high > performance impact in the hotpath it was only intended to be called > from the timestamping path. But it turns out that not zeroizing it > has uncovered the reading of an uninitialized member field of > DSA_SKB_CB, so in the future just be careful about what needs > initialization and remove this macro. > 2. DSA_SKB_CLONE() contains a flaw in its body definition (originally > put there to silence checkpatch.pl) and is unusable at this point > (will only cause NPE's when used). So remove it. > 3. For DSA_SKB_COPY() the same performance considerations apply as above > and therefore it's best to prune this function before it reaches a > stable kernel and potentially any users. > > Vladimir Oltean (3): > net: dsa: Initialize DSA_SKB_CB(skb)->deferred_xmit variable > net: dsa: Remove dangerous DSA_SKB_CLONE() macro > net: dsa: Remove the now unused DSA_SKB_CB_COPY() macro > > include/net/dsa.h | 15 --------------- > net/dsa/slave.c | 2 ++ > 2 files changed, 2 insertions(+), 15 deletions(-) > > -- > 2.17.1 >
The title was "Fix a bug and avoid dangerous usage patterns [...around DSA_SKB_CB]", not sure why it got trimmed.
