Re: [PATCH v8 net-next] net: drop_monitor: support drop reason

On 2/8/22 10:08 PM, menglong8.dong@gmail.com wrote:

From: Menglong Dong <redacted>

In the commit c504e5c2f964 ("net: skb: introduce kfree_skb_reason()")
drop reason is introduced to the tracepoint of kfree_skb. Therefore,
drop_monitor is able to report the drop reason to users by netlink.

The drop reasons are reported as string to users, which is exactly
the same as what we do when reporting it to ftrace.

Signed-off-by: Menglong Dong <redacted>
---
v8:
- pass drop reason to net_dm_packet_report_size()
- move drop reason validation to net_dm_packet_trace_kfree_skb_hit()

v7:
- take the size of NET_DM_ATTR_REASON into accounting in
  net_dm_packet_report_size()
- let compiler define the size of drop_reasons

v6:
- check the range of drop reason in net_dm_packet_report_fill()

v5:
- check if drop reason larger than SKB_DROP_REASON_MAX

v4:
- report drop reasons as string

v3:
- referring to cb->reason and cb->pc directly in
  net_dm_packet_report_fill()

v2:
- get a pointer to struct net_dm_skb_cb instead of local var for
  each field
---
 include/uapi/linux/net_dropmon.h |  1 +
 net/core/drop_monitor.c          | 41 +++++++++++++++++++++++++++-----
 2 files changed, 36 insertions(+), 6 deletions(-)

Reviewed-by: David Ahern <dsahern@kernel.org>