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net: tun: track dropped skb via kfree_skb_reason()

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The TUN can be used as vhost-net backend. E.g, the tun_net_xmit() is the
interface to forward the skb from TUN to vhost-net/virtio-net.

However, there are many "goto drop" in the TUN driver. Therefore, the
kfree_skb_reason() is involved at each "goto drop" to help userspace
ftrace/ebpf to track the reason for the loss of packets.

The below reasons are introduced:

- SKB_DROP_REASON_DEV_READY
- SKB_DROP_REASON_NOMEM
- SKB_DROP_REASON_HDR_TRUNC
- SKB_DROP_REASON_TAP_FILTER
- SKB_DROP_REASON_TAP_TXFILTER

Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Dongli Zhang
2022-03-04 06:55:07 -08:00
committed by David S. Miller
parent 45a15d89fb
commit 4b4f052e2d
3 changed files with 51 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
include/linux/skbuff.h
View File

@@ -424,7 +424,25 @@ enum skb_drop_reason {
SKB_DROP_REASON_DEV_HDR, /* device driver specific
* header/metadata is invalid
*/
/* the device is not ready to xmit/recv due to any of its data
* structure that is not up/ready/initialized, e.g., the IFF_UP is
* not set, or driver specific tun->tfiles[txq] is not initialized
*/
SKB_DROP_REASON_DEV_READY,
SKB_DROP_REASON_FULL_RING, /* ring buffer is full */
SKB_DROP_REASON_NOMEM, /* error due to OOM */
SKB_DROP_REASON_HDR_TRUNC, /* failed to trunc/extract the header
* from networking data, e.g., failed
* to pull the protocol header from
* frags via pskb_may_pull()
*/
SKB_DROP_REASON_TAP_FILTER, /* dropped by (ebpf) filter directly
* attached to tun/tap, e.g., via
* TUNSETFILTEREBPF
*/
SKB_DROP_REASON_TAP_TXFILTER, /* dropped by tx filter implemented
* at tun/tap, e.g., check_filter()
*/
SKB_DROP_REASON_MAX,
};

5
include/trace/events/skb.h
View File

@@ -55,7 +55,12 @@
EM(SKB_DROP_REASON_SKB_GSO_SEG, SKB_GSO_SEG) \
EM(SKB_DROP_REASON_SKB_UCOPY_FAULT, SKB_UCOPY_FAULT) \
EM(SKB_DROP_REASON_DEV_HDR, DEV_HDR) \
EM(SKB_DROP_REASON_DEV_READY, DEV_READY) \
EM(SKB_DROP_REASON_FULL_RING, FULL_RING) \
EM(SKB_DROP_REASON_NOMEM, NOMEM) \
EM(SKB_DROP_REASON_HDR_TRUNC, HDR_TRUNC) \
EM(SKB_DROP_REASON_TAP_FILTER, TAP_FILTER) \
EM(SKB_DROP_REASON_TAP_TXFILTER, TAP_TXFILTER) \
EMe(SKB_DROP_REASON_MAX, MAX)
#undef EM