diff mbox series

[v3] net/af_packet: remove timestamp from packet status

Message ID 1632420804-398-1-git-send-email-tudor.cornea@gmail.com (mailing list archive)
State Accepted
Delegated to: Ferruh Yigit
Headers show
Series [v3] net/af_packet: remove timestamp from packet status | expand

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ci/iol-aarch64-compile-testing success Testing PASS
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ci/checkpatch success coding style OK

Commit Message

Tudor Cornea Sept. 23, 2021, 6:13 p.m. UTC
We should eliminate the timestamp status from the packet
status. This should only matter if timestamping is enabled
on the socket, but we might hit a kernel bug, which is fixed
in newer releases.

For interfaces of type 'veth', the sent skb is forwarded
to the peer and back into the network stack which timestamps
it on the RX path if timestamping is enabled globally
(which happens if any socket enables timestamping).

When the skb is destructed, tpacket_destruct_skb() is called
and it calls __packet_set_timestamp() which doesn't check
the flags on the socket and returns the timestamp if it is
set in the skb (and for veth it is, as mentioned above).

See the following kernel commit for reference [1]:

net: packetmmap: fix only tx timestamp on request

The packetmmap tx ring should only return timestamps if requested
via setsockopt PACKET_TIMESTAMP, as documented. This allows
compatibility with non-timestamp aware user-space code which checks
tp_status == TP_STATUS_AVAILABLE; not expecting additional timestamp
flags to be set in tp_status.

[1] https://www.spinics.net/lists/kernel/msg3959391.html

Signed-off-by: Mihai Pogonaru <pogonarumihai@gmail.com>
Signed-off-by: Tudor Cornea <tudor.cornea@gmail.com>

---
v3:
* Place function name and parameters on a separate line.
v2:
* Remove compile-time check for kernel version
---
 drivers/net/af_packet/rte_eth_af_packet.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

Comments

Ferruh Yigit Sept. 28, 2021, 1:01 p.m. UTC | #1
On 9/23/2021 7:13 PM, Tudor Cornea wrote:
> We should eliminate the timestamp status from the packet
> status. This should only matter if timestamping is enabled
> on the socket, but we might hit a kernel bug, which is fixed
> in newer releases.
> 
> For interfaces of type 'veth', the sent skb is forwarded
> to the peer and back into the network stack which timestamps
> it on the RX path if timestamping is enabled globally
> (which happens if any socket enables timestamping).
> 
> When the skb is destructed, tpacket_destruct_skb() is called
> and it calls __packet_set_timestamp() which doesn't check
> the flags on the socket and returns the timestamp if it is
> set in the skb (and for veth it is, as mentioned above).
> 
> See the following kernel commit for reference [1]:
> 
> net: packetmmap: fix only tx timestamp on request
> 
> The packetmmap tx ring should only return timestamps if requested
> via setsockopt PACKET_TIMESTAMP, as documented. This allows
> compatibility with non-timestamp aware user-space code which checks
> tp_status == TP_STATUS_AVAILABLE; not expecting additional timestamp
> flags to be set in tp_status.
> 
> [1] https://www.spinics.net/lists/kernel/msg3959391.html
> 
> Signed-off-by: Mihai Pogonaru <pogonarumihai@gmail.com>
> Signed-off-by: Tudor Cornea <tudor.cornea@gmail.com>
> 

Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>

Applied to dpdk-next-net/main, thanks.
diff mbox series

Patch

diff --git a/drivers/net/af_packet/rte_eth_af_packet.c b/drivers/net/af_packet/rte_eth_af_packet.c
index b73b211..fcd8090 100644
--- a/drivers/net/af_packet/rte_eth_af_packet.c
+++ b/drivers/net/af_packet/rte_eth_af_packet.c
@@ -168,6 +168,26 @@  eth_af_packet_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 }
 
 /*
+ * Check if there is an available frame in the ring
+ */
+static inline bool
+tx_ring_status_available(uint32_t tp_status)
+{
+	/*
+	 * We eliminate the timestamp status from the packet status.
+	 * This should only matter if timestamping is enabled on the socket,
+	 * but there is a bug in the kernel which is fixed in newer releases.
+	 *
+	 * See the following kernel commit for reference:
+	 *     commit 171c3b151118a2fe0fc1e2a9d1b5a1570cfe82d2
+	 *     net: packetmmap: fix only tx timestamp on request
+	 */
+	tp_status &= ~(TP_STATUS_TS_SOFTWARE | TP_STATUS_TS_RAW_HARDWARE);
+
+	return tp_status == TP_STATUS_AVAILABLE;
+}
+
+/*
  * Callback to handle sending packets through a real NIC.
  */
 static uint16_t
@@ -212,8 +232,8 @@  eth_af_packet_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 		}
 
 		/* point at the next incoming frame */
-		if ((ppd->tp_status != TP_STATUS_AVAILABLE) &&
-		    (poll(&pfd, 1, -1) < 0))
+		if (!tx_ring_status_available(ppd->tp_status) &&
+		    poll(&pfd, 1, -1) < 0)
 			break;
 
 		/* copy the tx frame data */