From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesse Brandeburg Date: Fri, 8 Jan 2021 10:35:37 -0800 Subject: [Intel-wired-lan] [PATCH net-next v1 1/2] net: core: count drops from GRO In-Reply-To: References: <20210106215539.2103688-1-jesse.brandeburg@intel.com> <20210106215539.2103688-2-jesse.brandeburg@intel.com> Message-ID: <20210108103537.00005168@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: Eric Dumazet wrote: > > --- a/net/core/dev.c > > +++ b/net/core/dev.c > > @@ -6071,6 +6071,7 @@ static gro_result_t napi_skb_finish(struct napi_struct *napi, > > break; > > > > case GRO_DROP: > > + atomic_long_inc(&skb->dev->rx_dropped); > > kfree_skb(skb); > > break; > > > > @@ -6159,6 +6160,7 @@ static gro_result_t napi_frags_finish(struct napi_struct *napi, > > break; > > > > case GRO_DROP: > > + atomic_long_inc(&skb->dev->rx_dropped); > > napi_reuse_skb(napi, skb); > > break; > > > > > This is not needed. I think we should clean up ice instead. My patch 2 already did that. I was trying to address the fact that I'm *actually seeing* GRO_DROP return codes coming back from stack. I'll try to reproduce that issue again that I saw. Maybe modern kernels don't have the problem as frequently or at all. > Drivers are supposed to have allocated the skb (using > napi_get_frags()) before calling napi_gro_frags() ice doesn't use napi_get_frags/napi_gro_frags, so I'm not sure how this is relevant. > Only napi_gro_frags() would return GRO_DROP, but we supposedly could > crash at that point, since a driver is clearly buggy. seems unlikely since we don't call those functions. > We probably can remove GRO_DROP completely, assuming lazy drivers are fixed. This might be ok, but doesn't explain why I was seeing this return code (which was the whole reason I was trying to count them), however I may have been running on a distro kernel from redhat/centos 8 when I was seeing these events. I haven't fully completed spelunking all the different sources, but might be able to follow down the rabbit hole further. > diff --git a/net/core/dev.c b/net/core/dev.c > index 8fa739259041aaa03585b5a7b8ebce862f4b7d1d..c9460c9597f1de51957fdcfc7a64ca45bce5af7c > 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -6223,9 +6223,6 @@ gro_result_t napi_gro_frags(struct napi_struct *napi) > gro_result_t ret; > struct sk_buff *skb = napi_frags_skb(napi); > > - if (!skb) > - return GRO_DROP; > - > trace_napi_gro_frags_entry(skb); > > ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb)); This change (noted from your other patches is fine), and a likely improvement, thanks for sending those!