[dpdk-dev] [PATCH] net/af_packet: run on kernels without qdisc bypass support

Some older kernels do not support the PACKET_QDISC_BYPASS socket
option. Such an example is the CentOS 7 kernel (3.10).

If we only check for the definition of PACKET_QDISC_BYPASS, it might mean
that we will not be able to compile the PMD driver on a newer platform,
and run in on a machine with an older kernel.

Setting the socket option only if it is specifically requested from
the EAL arguments, allows us to have a way to run the PMD compiled
against newer kernel headers, on platforms having older kernels.

Signed-off-by: Tudor Cornea <redacted>
---
 drivers/net/af_packet/rte_eth_af_packet.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/net/af_packet/rte_eth_af_packet.c b/drivers/net/af_packet/rte_eth_af_packet.c
index 2e90e29..60b485a 100644
--- a/drivers/net/af_packet/rte_eth_af_packet.c
+++ b/drivers/net/af_packet/rte_eth_af_packet.c

@@ -749,13 +749,15 @@ rte_pmd_init_internals(struct rte_vdev_device *dev,
 		}
 
 #if defined(PACKET_QDISC_BYPASS)
-		rc = setsockopt(qsockfd, SOL_PACKET, PACKET_QDISC_BYPASS,
-				&qdisc_bypass, sizeof(qdisc_bypass));
-		if (rc == -1) {
-			PMD_LOG_ERRNO(ERR,
-				"%s: could not set PACKET_QDISC_BYPASS on AF_PACKET socket for %s",
-				name, pair->value);
-			goto error;
+		if (qdisc_bypass) {
+			rc = setsockopt(qsockfd, SOL_PACKET, PACKET_QDISC_BYPASS,
+					&qdisc_bypass, sizeof(qdisc_bypass));
+			if (rc == -1) {
+				PMD_LOG_ERRNO(ERR,
+					"%s: could not set PACKET_QDISC_BYPASS on AF_PACKET socket for %s",
+					name, pair->value);
+				goto error;
+			}
 		}
 #else
 		RTE_SET_USED(qdisc_bypass);

-- 
2.7.4

14/07/2021 11:28, Tudor Cornea:

Some older kernels do not support the PACKET_QDISC_BYPASS socket
option. Such an example is the CentOS 7 kernel (3.10).

If we only check for the definition of PACKET_QDISC_BYPASS, it might mean
that we will not be able to compile the PMD driver on a newer platform,
and run in on a machine with an older kernel.

Setting the socket option only if it is specifically requested from
the EAL arguments, allows us to have a way to run the PMD compiled
against newer kernel headers, on platforms having older kernels.

Signed-off-by: Tudor Cornea <redacted>

Applied, thanks.

I did a change in the patch while applying. See below:

14/07/2021 11:28, Tudor Cornea:

I move this #if below...

-		rc = setsockopt(qsockfd, SOL_PACKET, PACKET_QDISC_BYPASS,
-				&qdisc_bypass, sizeof(qdisc_bypass));
-		if (rc == -1) {
-			PMD_LOG_ERRNO(ERR,
-				"%s: could not set PACKET_QDISC_BYPASS on AF_PACKET socket for %s",
-				name, pair->value);
-			goto error;
+		if (qdisc_bypass) {

... here so we can...

+			rc = setsockopt(qsockfd, SOL_PACKET, PACKET_QDISC_BYPASS,
+					&qdisc_bypass, sizeof(qdisc_bypass));
+			if (rc == -1) {
+				PMD_LOG_ERRNO(ERR,
+					"%s: could not set PACKET_QDISC_BYPASS on AF_PACKET socket for %s",
+					name, pair->value);
+				goto error;
+			}
 		}
 #else
 		RTE_SET_USED(qdisc_bypass);

... drop this #else