[PATCH] net/af_packet: allow disabling packet fanout

[Tudor Cornea]

This allows us to control whether the PMD will attempt to use
the PACKET_FANOUT socket option, and allows the binary compiled
against newer kernel headers to run on an older kernel, which
lacks support for it.

Signed-off-by: Tudor Cornea <tudor.cor...@gmail.com>
---
 doc/guides/nics/af_packet.rst             |  4 ++-
 drivers/net/af_packet/rte_eth_af_packet.c | 32 ++++++++++++++++++-----
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/doc/guides/nics/af_packet.rst b/doc/guides/nics/af_packet.rst
index a343d3a961..42837031de 100644
--- a/doc/guides/nics/af_packet.rst
+++ b/doc/guides/nics/af_packet.rst
@@ -25,6 +25,8 @@ Some of these, in turn, will be used to configure the 
PACKET_MMAP settings.
 *   ``qpairs`` - number of Rx and Tx queues (optional, default 1);
 *   ``qdisc_bypass`` - set PACKET_QDISC_BYPASS option in AF_PACKET (optional,
     disabled by default);
+*   ``packet_fanout`` - set PACKET_FANOUT option in AF_PACKET (optional,
+    enabled by default);
 *   ``blocksz`` - PACKET_MMAP block size (optional, default 4096);
 *   ``framesz`` - PACKET_MMAP frame size (optional, default 2048B; Note: 
multiple
     of 16B);
@@ -64,7 +66,7 @@ framecnt=512):
 
 .. code-block:: console
 
-    
--vdev=eth_af_packet0,iface=tap0,blocksz=4096,framesz=2048,framecnt=512,qpairs=1,qdisc_bypass=0
+    
--vdev=eth_af_packet0,iface=tap0,blocksz=4096,framesz=2048,framecnt=512,qpairs=1,qdisc_bypass=0,packet_fanout=0
 
 Features and Limitations
 ------------------------
diff --git a/drivers/net/af_packet/rte_eth_af_packet.c 
b/drivers/net/af_packet/rte_eth_af_packet.c
index ceb8d9356a..521dbef317 100644
--- a/drivers/net/af_packet/rte_eth_af_packet.c
+++ b/drivers/net/af_packet/rte_eth_af_packet.c
@@ -36,6 +36,7 @@
 #define ETH_AF_PACKET_FRAMESIZE_ARG    "framesz"
 #define ETH_AF_PACKET_FRAMECOUNT_ARG   "framecnt"
 #define ETH_AF_PACKET_QDISC_BYPASS_ARG "qdisc_bypass"
+#define ETH_AF_PACKET_PACKET_FANOUT_ARG        "packet_fanout"
 
 #define DFLT_FRAME_SIZE                (1 << 11)
 #define DFLT_FRAME_COUNT       (1 << 9)
@@ -96,6 +97,7 @@ static const char *valid_arguments[] = {
        ETH_AF_PACKET_FRAMESIZE_ARG,
        ETH_AF_PACKET_FRAMECOUNT_ARG,
        ETH_AF_PACKET_QDISC_BYPASS_ARG,
+       ETH_AF_PACKET_PACKET_FANOUT_ARG,
        NULL
 };
 
@@ -709,6 +711,7 @@ rte_pmd_init_internals(struct rte_vdev_device *dev,
                        unsigned int framesize,
                        unsigned int framecnt,
                       unsigned int qdisc_bypass,
+                      unsigned int packet_fanout,
                        struct pmd_internals **internals,
                        struct rte_eth_dev **eth_dev,
                        struct rte_kvargs *kvlist)
@@ -926,14 +929,17 @@ rte_pmd_init_internals(struct rte_vdev_device *dev,
                        goto error;
                }
 
+               if (packet_fanout) {
 #if defined(PACKET_FANOUT)
-               rc = setsockopt(qsockfd, SOL_PACKET, PACKET_FANOUT,
-                               &fanout_arg, sizeof(fanout_arg));
-               if (rc == -1) {
-                       PMD_LOG_ERRNO(ERR,
-                               "%s: could not set PACKET_FANOUT on AF_PACKET 
socket for %s",
-                               name, pair->value);
-                       goto error;
+                       rc = setsockopt(qsockfd, SOL_PACKET, PACKET_FANOUT,
+                                       &fanout_arg, sizeof(fanout_arg));
+                       if (rc == -1) {
+                               PMD_LOG_ERRNO(ERR,
+                                       "%s: could not set PACKET_FANOUT "
+                                       "on AF_PACKET socket for %s",
+                                       name, pair->value);
+                               goto error;
+                       }
                }
 #endif
        }
@@ -1003,6 +1009,7 @@ rte_eth_from_packet(struct rte_vdev_device *dev,
        unsigned int framecount = DFLT_FRAME_COUNT;
        unsigned int qpairs = 1;
        unsigned int qdisc_bypass = 1;
+       unsigned int packet_fanout = 1;
 
        /* do some parameter checking */
        if (*sockfd < 0)
@@ -1065,6 +1072,16 @@ rte_eth_from_packet(struct rte_vdev_device *dev,
                        }
                        continue;
                }
+               if (strstr(pair->key, ETH_AF_PACKET_PACKET_FANOUT_ARG) != NULL) 
{
+                       packet_fanout = atoi(pair->value);
+                       if (packet_fanout > 1) {
+                               PMD_LOG(ERR,
+                                       "%s: invalid packet fanout value",
+                                       name);
+                               return -1;
+                       }
+                       continue;
+               }
        }
 
        if (framesize > blocksize) {
@@ -1091,6 +1108,7 @@ rte_eth_from_packet(struct rte_vdev_device *dev,
                                   blocksize, blockcount,
                                   framesize, framecount,
                                   qdisc_bypass,
+                                  packet_fanout,
                                   &internals, &eth_dev,
                                   kvlist) < 0)
                return -1;
-- 
2.34.1