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fixes for two more TSAN races - #651
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The client thread logs while setting up its call-home bind, so the log
callback can read the expected message while the server thread is still
writing it:
WARNING: ThreadSanitizer: data race (pid=3869790)
Read of size 8 at 0x555556aa75b0 by thread T7 (mutexes: write M0):
#0 strstr <null>
CESNET#1 test_msg_callback tests/test_ch.c:55:9
CESNET#2 nc_log_vprintf src/log.c:134:9
CESNET#3 nc_log_printf src/log.c:152:5
CESNET#4 nc_sock_bind_inet src/session_server.c
CESNET#5 nc_sock_listen_inet src/session_server.c:563:9
CESNET#6 nc_client_ch_add_bind_listen src/session_client.c:1765:12
CESNET#7 nc_client_ssh_ch_add_bind_listen src/session_client_ssh.c:1268:12
CESNET#8 client_thread_delete_while_session tests/test_ch.c:504:11
Previous write of size 8 at 0x555556aa75b0 by thread T8:
#0 __tsan_memcpy <null>
CESNET#1 server_thread_delete_while_session tests/test_ch.c:447:5
Location is global 'expected' of size 512 at 0x555556aa75b0
Reset both the buffer and the expected message under the lock.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The print callback may be changed while other threads are logging, as
test_ch does when the server thread installs its callback while the
client thread is already setting up its call-home bind:
WARNING: ThreadSanitizer: data race (pid=3869790)
Read of size 8 at 0x555556aa6f78 by thread T7:
#0 nc_log_vprintf src/log.c:133:9
CESNET#1 nc_log_printf src/log.c:152:5
CESNET#2 nc_sock_bind_inet src/session_server.c
CESNET#3 nc_sock_listen_inet src/session_server.c:563:9
CESNET#4 nc_client_ch_add_bind_listen src/session_client.c:1765:12
CESNET#5 nc_client_ssh_ch_add_bind_listen src/session_client_ssh.c:1268:12
CESNET#6 client_thread_delete_while_session tests/test_ch.c:504:11
Previous write of size 8 at 0x555556aa6f78 by thread T8:
#0 nc_set_print_clb_session src/log.c:159:15
CESNET#1 server_thread_delete_while_session tests/test_ch.c:445:5
Location is global 'print_clb' of size 8 at 0x555556aa6f78
Store it as an atomic pointer, just like the verbosity level.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
michalvasko
approved these changes
Oct 19, 2026
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I was checking whether commit ac86ff1 fixed all problems that I hit in #648, and there's a couple more.