[RFC 1/3] ss: drop the dead /proc fallback trigger in packet_show_sock()

[Stephen Hemminger <stephen@networkplumber.org>]

Commit a2b31976 ("ss: drop the /proc parsers for packet and netlink
sockets") removed the /proc/net/packet fallback but left behind the
code whose only purpose was to request it:

	/* use /proc/net/packet if all info are not available */
	if (!tb[PACKET_DIAG_MEMINFO])
		return -1;

That -1 used to propagate up so packet_show() would retry via
net_packet_open().  With no fallback left it is returned from an
rtnl_dump_filter() callback, which aborts the dump.  A kernel that
omits PACKET_DIAG_MEMINFO for a socket now silently truncates the
listing at that socket: everything after it is dropped and the exit
status is still 0.

The check is redundant anyway.  The code below already guards the
attribute with "if (tb[PACKET_DIAG_MEMINFO])" and simply leaves
stat.rq at 0 when it is absent, which is how the netlink path treats
every other optional attribute.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 misc/ss.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/misc/ss.c b/misc/ss.c
index 6ca6d406..0b7ba256 100644
--- a/misc/ss.c
+++ b/misc/ss.c
@@ -4773,10 +4773,6 @@ static int packet_show_sock(struct nlmsghdr *nlh, void *arg)
 	parse_rtattr(tb, PACKET_DIAG_MAX, (struct rtattr *)(r+1),
 		     nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*r)));
 
-	/* use /proc/net/packet if all info are not available */
-	if (!tb[PACKET_DIAG_MEMINFO])
-		return -1;
-
 	stat.type   = r->pdiag_type;
 	stat.prot   = r->pdiag_num;
 	stat.ino    = r->pdiag_ino;
-- 
2.53.0