[PATCH v5 bpf-next 12/17] selftests: xsk: remove sync_mutex_tx and atomic var

[Maciej Fijalkowski]

Although thread_common_ops() are called in both Tx and Rx threads,
testapp_validate() will not spawn Tx thread until Rx thread signals that
it has finished its initialization via condition variable.

Therefore, locking in thread_common_ops is not needed and furthermore Tx
thread does not have to spin on atomic variable.

Note that this simplification wouldn't be possible if there would still
be a common worker thread.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkow...@intel.com>
---
 tools/testing/selftests/bpf/xdpxceiver.c | 31 ++++++------------------
 tools/testing/selftests/bpf/xdpxceiver.h |  2 --
 2 files changed, 7 insertions(+), 26 deletions(-)

diff --git a/tools/testing/selftests/bpf/xdpxceiver.c 
b/tools/testing/selftests/bpf/xdpxceiver.c
index aeff5340be49..be7f4930dee9 100644
--- a/tools/testing/selftests/bpf/xdpxceiver.c
+++ b/tools/testing/selftests/bpf/xdpxceiver.c
@@ -121,17 +121,15 @@ static void __exit_with_error(int error, const char 
*file, const char *func, int
                               test_type == TEST_TYPE_BIDI ? "Bi-directional 
Sockets" : "",\
                               test_type == TEST_TYPE_STATS ? "Stats" : ""))
 
-static void pthread_init_mutex(void)
+static void init_sync_resources(void)
 {
        pthread_mutex_init(&sync_mutex, NULL);
-       pthread_mutex_init(&sync_mutex_tx, NULL);
        pthread_cond_init(&signal_rx_condition, NULL);
 }
 
-static void pthread_destroy_mutex(void)
+static void destroy_sync_resources(void)
 {
        pthread_mutex_destroy(&sync_mutex);
-       pthread_mutex_destroy(&sync_mutex_tx);
        pthread_cond_destroy(&signal_rx_condition);
 }
 
@@ -752,7 +750,7 @@ static void worker_pkt_validate(void)
        }
 }
 
-static void thread_common_ops(struct ifobject *ifobject, void *bufs, 
pthread_mutex_t *mutexptr)
+static void thread_common_ops(struct ifobject *ifobject, void *bufs)
 {
        int ctr = 0;
        int ret;
@@ -771,22 +769,13 @@ static void thread_common_ops(struct ifobject *ifobject, 
void *bufs, pthread_mut
 
        /* Retry Create Socket if it fails as xsk_socket__create()
         * is asynchronous
-        *
-        * Essential to lock Mutex here to prevent Tx thread from
-        * entering before Rx and causing a deadlock
         */
-       pthread_mutex_lock(mutexptr);
        while (ret && ctr < SOCK_RECONF_CTR) {
-               if (ifobject->fv.vector == rx)
-                       atomic_store(&spinning_rx, 1);
                xsk_configure_umem(ifobject, bufs, num_frames * 
XSK_UMEM__DEFAULT_FRAME_SIZE);
                ret = xsk_configure_socket(ifobject);
                usleep(USLEEP_MAX);
                ctr++;
        }
-       if (ifobject->fv.vector == rx)
-               atomic_store(&spinning_rx, 0);
-       pthread_mutex_unlock(mutexptr);
 
        if (ctr >= SOCK_RECONF_CTR)
                exit_with_error(ret);
@@ -803,16 +792,10 @@ static void *worker_testapp_validate_tx(void *arg)
        struct ethhdr *eth_hdr = (struct ethhdr *)pkt_data;
        struct ifobject *ifobject = (struct ifobject *)arg;
        struct generic_data data;
-       int spinningrxctr = 0;
        void *bufs = NULL;
 
        if (!bidi_pass)
-               thread_common_ops(ifobject, bufs, &sync_mutex_tx);
-
-       while (atomic_load(&spinning_rx) && spinningrxctr < SOCK_RECONF_CTR) {
-               spinningrxctr++;
-               usleep(USLEEP_MAX);
-       }
+               thread_common_ops(ifobject, bufs);
 
        for (int i = 0; i < num_frames; i++) {
                /*send EOT frame */
@@ -845,7 +828,7 @@ static void *worker_testapp_validate_rx(void *arg)
        void *bufs = NULL;
 
        if (!bidi_pass)
-               thread_common_ops(ifobject, bufs, &sync_mutex_tx);
+               thread_common_ops(ifobject, bufs);
 
        if (stat_test_type != STAT_TEST_RX_FILL_EMPTY)
                xsk_populate_fill_ring(ifobject->umem);
@@ -1103,7 +1086,7 @@ int main(int argc, char **argv)
 
        ksft_set_plan(TEST_MODE_MAX * TEST_TYPE_MAX);
 
-       pthread_init_mutex();
+       init_sync_resources();
 
        for (i = 0; i < TEST_MODE_MAX; i++) {
                for (j = 0; j < TEST_TYPE_MAX; j++)
@@ -1116,7 +1099,7 @@ int main(int argc, char **argv)
                free(ifdict[i]);
        }
 
-       pthread_destroy_mutex();
+       destroy_sync_resources();
 
        ksft_exit_pass();
 
diff --git a/tools/testing/selftests/bpf/xdpxceiver.h 
b/tools/testing/selftests/bpf/xdpxceiver.h
index 3945746900af..e304229d8a4c 100644
--- a/tools/testing/selftests/bpf/xdpxceiver.h
+++ b/tools/testing/selftests/bpf/xdpxceiver.h
@@ -146,9 +146,7 @@ static struct ifobject *ifdict_rx;
 static struct ifobject *ifdict_tx;
 
 /*threads*/
-atomic_int spinning_rx;
 pthread_mutex_t sync_mutex;
-pthread_mutex_t sync_mutex_tx;
 pthread_cond_t signal_rx_condition;
 pthread_t t0, t1;
 pthread_attr_t attr;
-- 
2.20.1