[PATCH iproute2] ss: add SK_MEMINFO_DROPS display

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.com>

SK_MEMINFO_DROPS is added in linux-4.7 for TCP, UDP and SCTP

skmem will display the socket drop count using d prefix as in :

$ ss -tm src :22 | more
State      Recv-Q Send-Q Local Address:Port    Peer Address:Port                
ESTAB      0      52     10.246.7.151:ssh      172.20.10.101:50759              
  
         skmem:(r0,rb8388608,t0,tb8388608,f1792,w2304,o0,bl0,d0)


Signed-off-by: Eric Dumazet <eduma...@google.com>
---
 include/linux/sock_diag.h |    1 +
 misc/ss.c                 |    4 ++++
 2 files changed, 5 insertions(+)

diff --git a/include/linux/sock_diag.h b/include/linux/sock_diag.h
index dafcb89..901231e 100644
--- a/include/linux/sock_diag.h
+++ b/include/linux/sock_diag.h
@@ -20,6 +20,7 @@ enum {
        SK_MEMINFO_WMEM_QUEUED,
        SK_MEMINFO_OPTMEM,
        SK_MEMINFO_BACKLOG,
+       SK_MEMINFO_DROPS,
 
        SK_MEMINFO_VARS,
 };
diff --git a/misc/ss.c b/misc/ss.c
index deefc96..3258584 100644
--- a/misc/ss.c
+++ b/misc/ss.c
@@ -1905,6 +1905,10 @@ static void print_skmeminfo(struct rtattr *tb[], int 
attrtype)
                (SK_MEMINFO_BACKLOG + 1) * sizeof(__u32))
                printf(",bl%u", skmeminfo[SK_MEMINFO_BACKLOG]);
 
+       if (RTA_PAYLOAD(tb[attrtype]) >=
+               (SK_MEMINFO_DROPS + 1) * sizeof(__u32))
+               printf(",d%u", skmeminfo[SK_MEMINFO_DROPS]);
+
        printf(")");
 }