diff mbox

[PATCHv2,3/7] linux-generic: pktio: handle transmit errors correctly

Message ID 1441360547-18999-3-git-send-email-stuart.haslam@linaro.org
State Superseded
Headers show

Commit Message

Stuart Haslam Sept. 4, 2015, 9:55 a.m. UTC
Errors which occur while sending packets via odp_pktio_send() aren't
handled correctly or even consistently across the two socket based
implementations.

The problems being addressed are;

 - calls may block indefinitely in certain error conditions (mmsg)
 - packets may be freed and reported as being sent correctly even though
   they weren't really sent (mmap)
 - return value doesn't always accurately reflect number of packets sent
 - inconsistent use of __odp_errno

Signed-off-by: Stuart Haslam <stuart.haslam@linaro.org>
---
 .../linux-generic/include/odp_packet_io_internal.h |  6 ++
 platform/linux-generic/pktio/socket.c              | 27 +++---
 platform/linux-generic/pktio/socket_mmap.c         | 96 +++++++++++-----------
 3 files changed, 70 insertions(+), 59 deletions(-)
diff mbox

Patch

diff --git a/platform/linux-generic/include/odp_packet_io_internal.h b/platform/linux-generic/include/odp_packet_io_internal.h
index a21c683..e6f57a4 100644
--- a/platform/linux-generic/include/odp_packet_io_internal.h
+++ b/platform/linux-generic/include/odp_packet_io_internal.h
@@ -28,6 +28,12 @@  extern "C" {
 #include <odp/hints.h>
 #include <net/if.h>
 
+/** Determine if a socket read/write error should be reported. Transient errors
+ *  that simply require the caller to retry are ignored, the _send/_recv APIs
+ *  are non-blocking and it is the caller's responsibility to retry if the
+ *  requested number of packets were not handled. */
+#define SOCK_ERR_REPORT(e) (e != EAGAIN && e != EWOULDBLOCK && e != EINTR)
+
 /* Forward declaration */
 struct pktio_if_ops;
 
diff --git a/platform/linux-generic/pktio/socket.c b/platform/linux-generic/pktio/socket.c
index 6fcdb46..93063d0 100644
--- a/platform/linux-generic/pktio/socket.c
+++ b/platform/linux-generic/pktio/socket.c
@@ -379,9 +379,7 @@  static int sock_mmsg_send(pktio_entry_t *pktio_entry,
 	struct iovec iovecs[ODP_PACKET_SOCKET_MAX_BURST_TX][ODP_BUFFER_MAX_SEG];
 	int ret;
 	int sockfd;
-	unsigned i;
-	unsigned sent_msgs = 0;
-	unsigned flags;
+	unsigned n, i;
 
 	if (pktio_entry->s.state == STATE_STOP) {
 		__odp_errno = EPERM;
@@ -400,17 +398,24 @@  static int sock_mmsg_send(pktio_entry_t *pktio_entry,
 								iovecs[i]);
 	}
 
-	flags = MSG_DONTWAIT;
-	for (i = 0; i < len; i += sent_msgs) {
-		ret = sendmmsg(sockfd, &msgvec[i], len - i, flags);
-		sent_msgs = ret > 0 ? (unsigned)ret : 0;
-		flags = 0;	/* blocking for next rounds */
+	for (i = 0; i < len; ) {
+		ret = sendmmsg(sockfd, &msgvec[i], len - i, MSG_DONTWAIT);
+		if (odp_unlikely(ret <= -1)) {
+			if (i == 0 && SOCK_ERR_REPORT(errno)) {
+				__odp_errno = errno;
+				ODP_ERR("sendmmsg(): %s\n", strerror(errno));
+				return -1;
+			}
+			break;
+		}
+
+		i += ret;
 	}
 
-	for (i = 0; i < len; i++)
-		odp_packet_free(pkt_table[i]);
+	for (n = 0; n < i; ++n)
+		odp_packet_free(pkt_table[n]);
 
-	return len;
+	return i;
 }
 
 /*
diff --git a/platform/linux-generic/pktio/socket_mmap.c b/platform/linux-generic/pktio/socket_mmap.c
index 3fd2b0f..f862327 100644
--- a/platform/linux-generic/pktio/socket_mmap.c
+++ b/platform/linux-generic/pktio/socket_mmap.c
@@ -174,49 +174,70 @@  static inline unsigned pkt_mmap_v2_tx(int sock, struct ring *ring,
 {
 	union frame_map ppd;
 	uint32_t pkt_len;
-	unsigned frame_num, next_frame_num;
+	unsigned first_frame_num, frame_num, frame_count;
 	int ret;
-	unsigned i = 0;
+	uint8_t *buf;
+	unsigned n, i = 0;
+	unsigned nb_tx = 0;
+	int send_errno;
 
-	frame_num = ring->frame_num;
+	first_frame_num = ring->frame_num;
+	frame_num = first_frame_num;
+	frame_count = ring->rd_num;
 
 	while (i < len) {
-		if (mmap_tx_kernel_ready(ring->rd[frame_num].iov_base)) {
-			ppd.raw = ring->rd[frame_num].iov_base;
+		ppd.raw = ring->rd[frame_num].iov_base;
+		if (!odp_unlikely(mmap_tx_kernel_ready(ppd.raw)))
+			break;
 
-			next_frame_num = (frame_num + 1) % ring->rd_num;
+		pkt_len = odp_packet_len(pkt_table[i]);
+		ppd.v2->tp_h.tp_snaplen = pkt_len;
+		ppd.v2->tp_h.tp_len = pkt_len;
 
-			pkt_len = odp_packet_len(pkt_table[i]);
-			ppd.v2->tp_h.tp_snaplen = pkt_len;
-			ppd.v2->tp_h.tp_len = pkt_len;
+		buf = (uint8_t *)ppd.raw + TPACKET2_HDRLEN -
+		       sizeof(struct sockaddr_ll);
+		odp_packet_copydata_out(pkt_table[i], 0, pkt_len, buf);
 
-			odp_packet_copydata_out(pkt_table[i], 0, pkt_len,
-						(uint8_t *)ppd.raw +
-						TPACKET2_HDRLEN -
-						sizeof(struct sockaddr_ll));
+		mmap_tx_user_ready(ppd.raw);
 
-			mmap_tx_user_ready(ppd.raw);
+		if (++frame_num >= frame_count)
+			frame_num = 0;
 
-			odp_packet_free(pkt_table[i]);
-			frame_num = next_frame_num;
-			i++;
-		} else {
+		i++;
+	}
+
+	ret = sendto(sock, NULL, 0, MSG_DONTWAIT, NULL, 0);
+	send_errno = errno;
+
+	/* On success, the return value indicates the number of bytes sent. On
+	 * failure a value of -1 is returned, even if the failure occurred
+	 * after some of the packets in the ring have already been sent, so we
+	 * need to inspect the packet status to determine which were sent. */
+	for (n = first_frame_num; n < first_frame_num + i; ++n) {
+		struct tpacket2_hdr *hdr = ring->rd[n].iov_base;
+
+		if (odp_likely(hdr->tp_status == TP_STATUS_AVAILABLE)) {
+			nb_tx++;
+		} else if (hdr->tp_status & TP_STATUS_WRONG_FORMAT) {
+			/* status will be cleared on the next send request */
 			break;
 		}
 	}
 
-	ring->frame_num = frame_num;
+	ring->frame_num = (ring->frame_num + nb_tx) % frame_count;
 
-	ret = sendto(sock, NULL, 0, MSG_DONTWAIT, NULL, 0);
-	if (ret == -1) {
-		if (errno != EAGAIN) {
-			__odp_errno = errno;
-			ODP_ERR("sendto(pkt mmap): %s\n", strerror(errno));
-			return -1;
-		}
+	if (odp_unlikely(ret == -1 &&
+			 nb_tx == 0 &&
+			 SOCK_ERR_REPORT(send_errno))) {
+		__odp_errno = send_errno;
+		ODP_ERR("sendto(pkt mmap): %s\n", strerror(send_errno));
+		return -1;
 	}
 
-	return i;
+	for (i = 0; i < nb_tx; ++i)
+		odp_packet_free(pkt_table[i]);
+
+	return nb_tx;
 }
 
 static void mmap_fill_ring(struct ring *ring, odp_pool_t pool_hdl, int fanout)
@@ -260,21 +281,6 @@  static void mmap_fill_ring(struct ring *ring, odp_pool_t pool_hdl, int fanout)
 	ring->flen = ring->req.tp_frame_size;
 }
 
-static int mmap_set_packet_loss_discard(int sock)
-{
-	int ret, discard = 1;
-
-	ret = setsockopt(sock, SOL_PACKET, PACKET_LOSS, (void *)&discard,
-			 sizeof(discard));
-	if (ret == -1) {
-		__odp_errno = errno;
-		ODP_ERR("setsockopt(PACKET_LOSS): %s\n", strerror(errno));
-		return -1;
-	}
-
-	return 0;
-}
-
 static int mmap_setup_ring(int sock, struct ring *ring, int type,
 			   odp_pool_t pool_hdl, int fanout)
 {
@@ -284,12 +290,6 @@  static int mmap_setup_ring(int sock, struct ring *ring, int type,
 	ring->type = type;
 	ring->version = TPACKET_V2;
 
-	if (type == PACKET_TX_RING) {
-		ret = mmap_set_packet_loss_discard(sock);
-		if (ret != 0)
-			return -1;
-	}
-
 	mmap_fill_ring(ring, pool_hdl, fanout);
 
 	ret = setsockopt(sock, SOL_PACKET, type, &ring->req, sizeof(ring->req));