netdev - [PATCH bpf-next 08/10] selftests: xsk: rely on pkts_in_flight in wait_for_tx

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Date:   Fri, 10 Jun 2022 17:09:21 +0200
From:   Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To:     bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net
Cc:     netdev@...r.kernel.org, magnus.karlsson@...el.com,
        bjorn@...nel.org, Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Subject: [PATCH bpf-next 08/10] selftests: xsk: rely on pkts_in_flight in wait_for_tx_completion()

Some of the drivers that implement support for AF_XDP Zero Copy (like
ice) can have lazy approach for cleaning Tx descriptors. For ZC, when
descriptor is cleaned, it is placed onto AF_XDP completion queue. This
means that current implementation of wait_for_tx_completion() in
xdpxceiver can get onto infinite loop, as some of the descriptors can
never reach CQ.

This function can be changed to rely on pkts_in_flight instead.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
---
 tools/testing/selftests/bpf/xdpxceiver.c | 3 ++-
 tools/testing/selftests/bpf/xdpxceiver.h | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/xdpxceiver.c b/tools/testing/selftests/bpf/xdpxceiver.c
index 316f1dd338fc..c9385690af09 100644
--- a/tools/testing/selftests/bpf/xdpxceiver.c
+++ b/tools/testing/selftests/bpf/xdpxceiver.c
@@ -965,7 +965,7 @@ static int __send_pkts(struct ifobject *ifobject, u32 *pkt_nb)
 
 static void wait_for_tx_completion(struct xsk_socket_info *xsk)
 {
-	while (xsk->outstanding_tx)
+	while (pkts_in_flight)
 		complete_pkts(xsk, BATCH_SIZE);
 }
 
@@ -1269,6 +1269,7 @@ static void *worker_testapp_validate_rx(void *arg)
 		pthread_mutex_unlock(&pacing_mutex);
 	}
 
+	pkts_in_flight = 0;
 	pthread_exit(NULL);
 }
 
diff --git a/tools/testing/selftests/bpf/xdpxceiver.h b/tools/testing/selftests/bpf/xdpxceiver.h
index b7aa6c7cf2be..f364a92675f8 100644
--- a/tools/testing/selftests/bpf/xdpxceiver.h
+++ b/tools/testing/selftests/bpf/xdpxceiver.h
@@ -170,6 +170,6 @@ pthread_barrier_t barr;
 pthread_mutex_t pacing_mutex = PTHREAD_MUTEX_INITIALIZER;
 pthread_cond_t pacing_cond = PTHREAD_COND_INITIALIZER;
 
-int pkts_in_flight;
+volatile int pkts_in_flight;
 
 #endif				/* XDPXCEIVER_H */
-- 
2.27.0