selftests: rds: Add RDS_LOG_DIR env variable

This patch modifies the rds selftest to look for an env variable
RDS_LOG_DIR, and log all traces, pcaps and gcov collections to
the folder specified in RDS_LOG_DIR.  If RDS_LOG_DIR is unset,
logs are not collected.

Signed-off-by: Allison Henderson <achender@kernel.org>
Link: https://patch.msgid.link/20260504054143.4027538-6-achender@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/rds/README.txt

@@ -15,7 +15,9 @@ USAGE:
 	       [-u packet_duplicate] [-t timeout]
 
 OPTIONS:
-	-d	Log directory.  Defaults to tools/testing/selftests/net/rds/rds_logs
+	-d	Log directory.  If set, logs will be stored in the
+		given dir, or skipped if unset.  Log dir can also be
+		set through the RDS_LOG_DIR env variable
 
 	-l	Simulates a percentage of packet loss
 
@@ -25,6 +27,16 @@ OPTIONS:
 
 	-t	Test timeout.  Defaults to tools/testing/selftests/net/rds/settings
 
+ENV VARIABLES:
+	RDS_LOG_DIR	Log directory.  If set, logs will be stored in
+			the given dir, or skipped if unset. Log dir
+			can also be set with the -d flag.
+
+			Use with --rwdir on the CI path to retain logs after
+			test compleation.  Log dir end point must be within
+			the specified --rwdir path for logs to persist on
+			the host.
+
 EXAMPLE:
 
     # Create a suitable gcov enabled .config
@@ -41,6 +53,7 @@ EXAMPLE:
 
     # launch the tests in a VM
     vng -v --rwdir ./ --run . --user root --cpus 4 -- \
-        "export PYTHONPATH=tools/testing/selftests/net/; tools/testing/selftests/net/rds/run.sh"
+        "export PYTHONPATH=tools/testing/selftests/net/; \
+         export RDS_LOG_DIR=tools/testing/selftests/net/rds/rds_logs; \
+         tools/testing/selftests/net/rds/run.sh"
 
-An HTML coverage report will be output in tools/testing/selftests/net/rds/rds_logs/coverage/.

tools/testing/selftests/net/rds/run.sh

@@ -150,28 +150,26 @@ check_env()
 	fi
 }
 
-LOG_DIR="$current_dir"/rds_logs
-PLOSS=0
-PCORRUPT=0
-PDUP=0
+LOG_DIR="${RDS_LOG_DIR:-}"
 TIMEOUT=$timeout
 GENERATE_GCOV_REPORT=1
+FLAGS=()
 while getopts "d:l:c:u:t:" opt; do
   case ${opt} in
     d)
       LOG_DIR=${OPTARG}
       ;;
     l)
-      PLOSS=${OPTARG}
+      FLAGS+=("-l" "${OPTARG}")
       ;;
     c)
-      PCORRUPT=${OPTARG}
+      FLAGS+=("-c" "${OPTARG}")
       ;;
     t)
       TIMEOUT=${OPTARG}
       ;;
     u)
-      PDUP=${OPTARG}
+      FLAGS+=("-u" "${OPTARG}")
       ;;
     :)
       echo "USAGE: run.sh [-d logdir] [-l packet_loss] [-c packet_corruption]" \
@@ -185,30 +183,37 @@ while getopts "d:l:c:u:t:" opt; do
   esac
 done
 
-
 check_env
 check_conf
 check_gcov_conf
 
+TRACE_CMD=()
+if [[ -n "$LOG_DIR" ]]; then
+   rm -fr "$LOG_DIR"
+   FLAGS+=("-d" "$LOG_DIR")
 
-rm -fr "$LOG_DIR"
-TRACE_FILE="${LOG_DIR}/rds-strace.txt"
-COVR_DIR="${LOG_DIR}/coverage/"
-mkdir -p  "$LOG_DIR"
-mkdir -p "$COVR_DIR"
+   TRACE_FILE="${LOG_DIR}/rds-strace.txt"
+   COVR_DIR="${LOG_DIR}/coverage/"
+   mkdir -p  "$LOG_DIR"
+   mkdir -p "$COVR_DIR"
+
+   echo Traces will be logged to "${TRACE_FILE}"
+   rm -f "$TRACE_FILE"
+
+   TRACE_CMD=(strace -T -tt -o "${TRACE_FILE}")
+fi
 
 set +e
 echo running RDS tests...
-echo Traces will be logged to "$TRACE_FILE"
-rm -f "$TRACE_FILE"
-strace -T -tt -o "$TRACE_FILE" python3 "$(dirname "$0")/test.py" \
-	-t "$TIMEOUT" -d "$LOG_DIR" -l "$PLOSS" -c "$PCORRUPT" \
-	-u "$PDUP"
+"${TRACE_CMD[@]}" python3 "$(dirname "$0")/test.py" "${FLAGS[@]}" -t "$TIMEOUT"
 
 test_rc=$?
-dmesg > "${LOG_DIR}/dmesg.out"
 
-if [ "$GENERATE_GCOV_REPORT" -eq 1 ]; then
+if [[ -n "$LOG_DIR" ]]; then
+   dmesg > "${LOG_DIR}/dmesg.out"
+fi
+
+if [[ -n "$LOG_DIR" ]] && [ "$GENERATE_GCOV_REPORT" -eq 1 ]; then
        echo saving coverage data...
        (set +x; cd /sys/kernel/debug/gcov; find ./* -name '*.gcda' | \
        while read -r f

tools/testing/selftests/net/rds/test.py

@@ -82,7 +82,7 @@ def signal_handler(_sig, _frame):
 parser = argparse.ArgumentParser(description="init script args",
                   formatter_class=argparse.ArgumentDefaultsHelpFormatter)
 parser.add_argument("-d", "--logdir", action="store",
-                    help="directory to store logs", default="/tmp")
+                    help="directory to store logs", default=None)
 parser.add_argument('-t', '--timeout', help="timeout to terminate hung test",
                     type=int, default=0)
 parser.add_argument('-l', '--loss', help="Simulate tcp packet loss",
@@ -128,16 +128,17 @@ ip(f"-n {NET1} route add {addrs[0][0]}/32 dev {VETH1}")
 # and communicating by doing a single ping
 ip(f"netns exec {NET0} ping -c 1 {addrs[1][0]}")
 
-# Start a packet capture on each network
 tcpdump_procs = []
-for net in [NET0, NET1]:
-    pcap = logdir+'/'+net+'.pcap'
-    fd, pcap_tmp = tempfile.mkstemp(suffix=".pcap", prefix=f"{net}-", dir="/tmp")
-    # pylint: disable-next=consider-using-with
-    p = subprocess.Popen(
-        ['ip', 'netns', 'exec', net,
-         '/usr/sbin/tcpdump', '-i', 'any', '-w', pcap_tmp])
-    tcpdump_procs.append((p, pcap_tmp, pcap, fd))
+# Start a packet capture on each network
+if logdir is not None:
+    for net in [NET0, NET1]:
+        pcap = logdir+'/'+net+'.pcap'
+        fd, pcap_tmp = tempfile.mkstemp(suffix=".pcap", prefix=f"{net}-", dir="/tmp")
+        # pylint: disable-next=consider-using-with
+        p = subprocess.Popen(
+            ['ip', 'netns', 'exec', net,
+             '/usr/sbin/tcpdump', '-i', 'any', '-w', pcap_tmp])
+        tcpdump_procs.append((p, pcap_tmp, pcap, fd))
 
 # simulate packet loss, duplication and corruption
 for net, iface in [(NET0, VETH0), (NET1, VETH1)]:
@@ -252,12 +253,13 @@ for s in sockets:
 
 print(f"getsockopt(): {nr_success}/{nr_error}")
 
-print("Stopping network packet captures")
-for p, pcap_tmp, pcap, fd in tcpdump_procs:
-    p.terminate()
-    p.wait()
-    os.close(fd)
-    shutil.move(pcap_tmp, pcap)
+if logdir is not None:
+    print("Stopping network packet captures")
+    for p, pcap_tmp, pcap, fd in tcpdump_procs:
+        p.terminate()
+        p.wait()
+        os.close(fd)
+        shutil.move(pcap_tmp, pcap)
 
 # We're done sending and receiving stuff, now let's check if what
 # we received is what we sent.