[global] drop usage of sendmmsg inside libknet

as requested by different kernel developers, we should stop
using both sendmmsg and recvmmsg.

as temporary solution use Jan's compat wrappers. the whole TX/RX
code will need review to do a full proper switch since all
error codes will change and propagate differently to transport hooks
and knet_send_sync users

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>

configure.ac

@@ -184,7 +184,6 @@ AC_CHECK_FUNCS([strrchr])
 AC_CHECK_FUNCS([strstr])
 AC_CHECK_FUNCS([clock_gettime])
 AC_CHECK_FUNCS([strcasecmp])
-AC_CHECK_FUNCS([sendmmsg])
 AC_CHECK_FUNCS([recvmmsg])
 AC_CHECK_FUNCS([kevent])
 # if neither sys/epoll.h nor kevent are present, we should fail.

libknet/compat.c

@@ -14,40 +14,6 @@
 
 #include "compat.h"
 
-#ifndef HAVE_SENDMMSG
-int sendmmsg(int sockfd, struct mmsghdr *msgvec, unsigned int vlen,
-    unsigned int flags)
-{
-#ifdef SYS_sendmmsg
-	/*
-	 * For systems where kernel supports sendmmsg but glibc doesn't (RHEL 6)
-	 */
-	return (syscall(SYS_sendmmsg, sockfd, msgvec, vlen, flags));
-#else
-	/*
-	 * Generic implementation of sendmmsg using sendmsg
-	 */
-	unsigned int i;
-	ssize_t ret;
-
-	if (vlen == 0) {
-		return (0);
-	}
-
-	for (i = 0; i < vlen; i++) {
-		ret = sendmsg(sockfd, &msgvec[i].msg_hdr, flags);
-		if (ret >= 0) {
-			msgvec[i].msg_len = ret;
-		} else {
-			break ;
-		}
-	}
-
-	return ((ret >= 0) ? vlen : ret);
-#endif
-}
-#endif
-
 #ifndef HAVE_RECVMMSG
 extern int recvmmsg(int sockfd, struct mmsghdr *msgvec, unsigned int vlen,
     unsigned int flags, struct timespec *timeout)

libknet/compat.h

@@ -17,20 +17,13 @@
 /* FreeBSD has recvmmsg but it's a buggy wrapper */
 #ifdef __FreeBSD__
 #define recvmmsg COMPAT_recvmmsg
-#define sendmmsg COMPAT_sendmmsg
 #undef HAVE_RECVMMSG
-#undef HAVE_SENDMMSG
 #endif
 
 #ifndef MSG_WAITFORONE
 #define MSG_WAITFORONE  0x10000
 #endif
 
-#ifndef HAVE_SENDMMSG
-extern int sendmmsg(int sockfd, struct mmsghdr *msgvec, unsigned int vlen,
-    unsigned int flags);
-#endif
-
 #ifndef HAVE_RECVMMSG
 extern int recvmmsg(int sockfd, struct mmsghdr *msgvec, unsigned int vlen,
     unsigned int flags, struct timespec *timeout);

libknet/threads_tx.c

@@ -49,8 +49,8 @@ static int _dispatch_to_links(knet_handle_t knet_h, struct knet_host *dst_host,
 retry:
 		cur = &msg[prev_sent];
 
-		sent_msgs = sendmmsg(dst_host->link[dst_host->active_links[link_idx]].outsock,
-				     (struct mmsghdr *)&cur[0], msgs_to_send - prev_sent, MSG_DONTWAIT | MSG_NOSIGNAL);
+		sent_msgs = _sendmmsg(dst_host->link[dst_host->active_links[link_idx]].outsock,
+				      &cur[0], msgs_to_send - prev_sent, MSG_DONTWAIT | MSG_NOSIGNAL);
 		savederrno = errno;
 
 		err = knet_h->transport_ops[dst_host->link[dst_host->active_links[link_idx]].transport_type]->transport_tx_sock_error(knet_h, dst_host->link[dst_host->active_links[link_idx]].outsock, sent_msgs, savederrno);

libknet/transport_common.c

@@ -15,6 +15,31 @@
 #include "common.h"
 #include "transports.h"
 
+/*
+ * reuse Jan Friesse's compat layer as wrapper to drop usage of sendmmsg
+ *
+ * TODO: kill those wrappers once we work on packet delivery guaranteed
+ */
+
+int _sendmmsg(int sockfd, struct knet_mmsghdr *msgvec, unsigned int vlen, unsigned int flags)
+{
+	int savederrno = 0, err = 0;
+	unsigned int i;
+
+	for (i = 0; i < vlen; i++) {
+		err = sendmsg(sockfd, &msgvec[i].msg_hdr, flags);
+		savederrno = errno;
+		if (err >= 0) {
+			msgvec[i].msg_len = err;
+		} else {
+			break;
+		}
+	}
+
+	errno = savederrno;
+	return ((err >= 0) ? vlen : err);
+}
+
 int _configure_common_socket(knet_handle_t knet_h, int sock, const char *type)
 {
 	int err = 0, savederrno = 0;

libknet/transports.h

@@ -21,4 +21,6 @@ void _close_socketpair(knet_handle_t knet_h, int *sock);
 int _set_fd_tracker(knet_handle_t knet_h, int sockfd, uint8_t transport, uint8_t data_type, void *data);
 int _is_valid_fd(knet_handle_t knet_h, int sockfd);
 
+int _sendmmsg(int sockfd, struct knet_mmsghdr *msgvec, unsigned int vlen, unsigned int flags);
+
 #endif