[PATCH net-next] tools: Fix MSG_SPLICE_PAGES build error in trace tools

[David Howells <dhowells@redhat.com>]

The following error is being seen the perf tools because they have their
own copies of a lot of kernel headers:

In file included from builtin-trace.c:907:
trace/beauty/msg_flags.c: In function 'syscall_arg__scnprintf_msg_flags':
trace/beauty/msg_flags.c:28:21: error: 'MSG_SPLICE_PAGES' undeclared (first use in this function)
   28 |         if (flags & MSG_##n) { \
      |                     ^~~~
trace/beauty/msg_flags.c:50:9: note: in expansion of macro 'P_MSG_FLAG'
   50 |         P_MSG_FLAG(SPLICE_PAGES);
      |         ^~~~~~~~~~
trace/beauty/msg_flags.c:28:21: note: each undeclared identifier is reported only once for each function it appears in
   28 |         if (flags & MSG_##n) { \
      |                     ^~~~
trace/beauty/msg_flags.c:50:9: note: in expansion of macro 'P_MSG_FLAG'
   50 |         P_MSG_FLAG(SPLICE_PAGES);
      |         ^~~~~~~~~~

Fix this by (1) adding MSG_SPLICE_PAGES to
tools/perf/trace/beauty/include/linux/socket.h - which looks like it ought
to work, but doesn't, and (2) defining it conditionally in the file on
which the error occurs (suggested by Matthieu Baerts - this is also done
for some other flags).

Fixes: b848b26c6672 ("net: Kill MSG_SENDPAGE_NOTLAST")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20230626112847.2ef3d422@canb.auug.org.au/
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Matthieu Baerts <matthieu.baerts@tessares.net>
cc: Arnaldo Carvalho de Melo <acme@redhat.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: bpf@vger.kernel.org
cc: dccp@vger.kernel.org
cc: linux-crypto@vger.kernel.org
cc: mptcp@lists.linux.dev
cc: netdev@vger.kernel.org
cc: tipc-discussion@lists.sourceforge.net
cc: virtualization@lists.linux-foundation.org
---
 include/linux/socket.h |    1 +
 msg_flags.c            |    3 +++
 2 files changed, 4 insertions(+)

diff --git a/tools/perf/trace/beauty/include/linux/socket.h b/tools/perf/trace/beauty/include/linux/socket.h
index 3bef212a24d7..77cb707a566a 100644
--- a/tools/perf/trace/beauty/include/linux/socket.h
+++ b/tools/perf/trace/beauty/include/linux/socket.h
@@ -326,6 +326,7 @@ struct ucred {
 					  */
 
 #define MSG_ZEROCOPY	0x4000000	/* Use user data in kernel path */
+#define MSG_SPLICE_PAGES 0x8000000	/* Splice the pages from the iterator in sendmsg() */
 #define MSG_FASTOPEN	0x20000000	/* Send data in TCP SYN */
 #define MSG_CMSG_CLOEXEC 0x40000000	/* Set close_on_exec for file
 					   descriptor received through
diff --git a/tools/perf/trace/beauty/msg_flags.c b/tools/perf/trace/beauty/msg_flags.c
index 5cdebd7ece7e..aa9934020232 100644
--- a/tools/perf/trace/beauty/msg_flags.c
+++ b/tools/perf/trace/beauty/msg_flags.c
@@ -8,6 +8,9 @@
 #ifndef MSG_WAITFORONE
 #define MSG_WAITFORONE		   0x10000
 #endif
+#ifndef MSG_SPLICE_PAGES
+#define MSG_SPLICE_PAGES	0x8000000
+#endif
 #ifndef MSG_FASTOPEN
 #define MSG_FASTOPEN		0x20000000
 #endif