net/rds/test.py sees a segfault in tcpdump when executed through the ksft runner.
[ 21.903713] tcpdump[1469]: segfault at 0 ip 000072100e99126d sp 00007ffccf740fd0 error 4 [ 21.903721] in libc.so.6[16a26d,7798b149a000+188000] [ 21.905074] in libc.so.6[16a26d,72100e84f000+188000] likely on CPU 5 (core 5, socket 0) [ 21.905084] Code: 00 0f 85 a0 00 00 00 48 83 c4 38 89 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 44 00 00 48 8b 05 91 8b 09 00 8b 4d ac 64 89 08 <41> 0f b6 07 83 e8 2b a8 fd 0f 84 54 ff ff ff 49 8b 36 4c 89 ff e8 [ 21.906760] likely on CPU 9 (core 9, socket 0) [ 21.913469] Code: 00 0f 85 a0 00 00 00 48 83 c4 38 89 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 44 00 00 48 8b 05 91 8b 09 00 8b 4d ac 64 89 08 <41> 0f b6 07 83 e8 2b a8 fd 0f 84 54 ff ff ff 49 8b 36 4c 89 ff e8 The os.fork() call creates extra complexity because it forks the entire process including the python interpreter. ip() then calls cmd() which creates a subprocess.Popen. We can avoid the extra layering by simply calling subprocess.Popen directly. Track the process handles directly and terminate them at cleanup rather than relying on killall. Further tcpdump's -Z flag attempts to change savefile ownership, which is not supported by the 9p protocol. Fix this by writing pcap captures to "/tmp" during the test and move them to the log directory after tcpdump exits. Signed-off-by: Allison Henderson <[email protected]> --- tools/testing/selftests/net/rds/test.py | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/tools/testing/selftests/net/rds/test.py b/tools/testing/selftests/net/rds/test.py index 8256afe6ad6f..93e23e8b256c 100755 --- a/tools/testing/selftests/net/rds/test.py +++ b/tools/testing/selftests/net/rds/test.py @@ -11,8 +11,8 @@ import signal import socket import subprocess import sys -from pwd import getpwuid -from os import stat +import tempfile +import shutil # Allow utils module to be imported from different directory this_dir = os.path.dirname(os.path.realpath(__file__)) @@ -125,14 +125,14 @@ ip(f"-n {NET1} route add {addrs[0][0]}/32 dev {VETH1}") 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]: - tcpdump_pid = os.fork() - if tcpdump_pid == 0: - pcap = logdir+'/'+net+'.pcap' - subprocess.check_call(['touch', pcap]) - user = getpwuid(stat(pcap).st_uid).pw_name - ip(f"netns exec {net} /usr/sbin/tcpdump -Z {user} -i any -w {pcap}") - sys.exit(0) + pcap = logdir+'/'+net+'.pcap' + fd, pcap_tmp = tempfile.mkstemp(suffix=".pcap", prefix=f"{net}-", dir="/tmp") + 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)]: @@ -248,7 +248,11 @@ for s in sockets: print(f"getsockopt(): {nr_success}/{nr_error}") print("Stopping network packet captures") -subprocess.check_call(['killall', '-q', 'tcpdump']) +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. -- 2.43.0
