selftests: drivers: net: hw: Modify toeplitz.c to poll for packets

Prior to this the receiver would sleep for the configured timeout,
then attempt to receive as many packets as possible. This would result
in a large burst of packets, and we don't necessarily need that many samples.

The tests now run faster.

Before

 ok 12 toeplitz.test.rps_udp_ipv6
 # Totals: pass:12 fail:0 xfail:0 xpass:0 skip:0 error:0

 real	0m54.792s
 user	0m12.486s
 sys	0m10.887s

After

 ok 12 toeplitz.test.rps_udp_ipv6
 # Totals: pass:12 fail:0 xfail:0 xpass:0 skip:0 error:0

 real	0m36.892s
 user	0m4.203s
 sys	0m8.314s

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Dimitri Daskalakis <dimitri.daskalakis1@gmail.com>
Link: https://patch.msgid.link/20260207013018.551347-1-dimitri.daskalakis1@gmail.com
[pabeni@redhat.com: whitespaces fixes]
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Dimitri Daskalakis

tools/testing/selftests/drivers/net/hw/toeplitz.c

@@ -72,6 +72,8 @@
 
 #define RPS_MAX_CPUS 16UL	/* must be a power of 2 */
 
+#define MIN_PKT_SAMPLES 40	/* minimum number of packets to receive */
+
 /* configuration options (cmdline arguments) */
 static uint16_t cfg_dport =	8000;
 static int cfg_family =		AF_INET6;
@@ -251,15 +253,31 @@ static bool recv_block(struct ring_state *ring)
 	return true;
 }
 
-/* simple test: sleep once unconditionally and then process all rings */
+/* simple test: process all rings until MIN_PKT_SAMPLES packets are received,
+ * or the test times out.
+ */
 static void process_rings(void)
 {
+	struct timeval start, now;
+	bool pkts_found = true;
+	long elapsed_usec;
 	int i;
 
-	usleep(1000 * cfg_timeout_msec);
+	gettimeofday(&start, NULL);
 
-	for (i = 0; i < num_cpus; i++)
-		do {} while (recv_block(&rings[i]));
+	do {
+		if (!pkts_found)
+			usleep(100);
+
+		pkts_found = false;
+		for (i = 0; i < num_cpus; i++)
+			pkts_found |= recv_block(&rings[i]);
+
+		gettimeofday(&now, NULL);
+		elapsed_usec = (now.tv_sec - start.tv_sec) * 1000000 +
+			       (now.tv_usec - start.tv_usec);
+	} while (frames_received - frames_nohash < MIN_PKT_SAMPLES &&
+		 elapsed_usec < cfg_timeout_msec * 1000);
 
 	fprintf(stderr, "count: pass=%u nohash=%u fail=%u\n",
 		frames_received - frames_nohash - frames_error,