Using SANITIZE=thread made t3008-ls-files-lazy-init-name-hash.sh hit
the potential race below.
What seems to happen is, threaded_lazy_init_name_hash ends up using
hashmap_add on the_index.dir_hash from two threads in a way that tsan
considers racy. While the buckets each have their own mutex, the "size"
does not. So it might end up with the wrong (lower) value. The size is
used to determine when to resize, but that should be fine, since
resizing is turned off due to threading anyway.
If the size is ever used for something else, the consequences might
range from cosmetic error to devastating. I have a "feeling" the size is
not used at the time, although maybe it is, in some roundabout way which
I'm not seeing.
Martin
WARNING: ThreadSanitizer: data race (pid=10554)
Read of size 4 at 0x00000082d488 by thread T2 (mutexes: write M16):
#0 hashmap_add hashmap.c:209 (test-lazy-init-name-hash+0x000000438b7d)
#1 hash_dir_entry_with_parent_and_prefix name-hash.c:302 (test-lazy-init-name-hash+0x00000043ea6c)
#2 handle_range_dir name-hash.c:347 (test-lazy-init-name-hash+0x00000043ea6c)
#3 handle_range_1 name-hash.c:415 (test-lazy-init-name-hash+0x00000043ea6c)
#4 lazy_dir_thread_proc name-hash.c:471 (test-lazy-init-name-hash+0x00000043ea6c)
#5 <null> <null> (libtsan.so.0+0x0000000230d9)
Previous write of size 4 at 0x00000082d488 by thread T1 (mutexes: write M31):
#0 hashmap_add hashmap.c:209 (test-lazy-init-name-hash+0x000000438b90)
#1 hash_dir_entry_with_parent_and_prefix name-hash.c:302 (test-lazy-init-name-hash+0x00000043e0f2)
#2 handle_range_dir name-hash.c:347 (test-lazy-init-name-hash+0x00000043e0f2)
#3 handle_range_1 name-hash.c:415 (test-lazy-init-name-hash+0x00000043e0f2)
#4 handle_range_dir name-hash.c:380 (test-lazy-init-name-hash+0x00000043e709)
#5 handle_range_1 name-hash.c:415 (test-lazy-init-name-hash+0x00000043e709)
#6 lazy_dir_thread_proc name-hash.c:471 (test-lazy-init-name-hash+0x00000043e709)
#7 <null> <null> (libtsan.so.0+0x0000000230d9)
Location is global 'the_index' of size 208 at 0x00000082d400 (test-lazy-init-name-hash+0x00000082d488)
Mutex M16 (0x7d640001a5b8) created at:
#0 pthread_mutex_init <null> (libtsan.so.0+0x0000000280b5)
#1 init_recursive_mutex thread-utils.c:73 (test-lazy-init-name-hash+0x0000004d829b)
#2 init_dir_mutex name-hash.c:241 (test-lazy-init-name-hash+0x00000043d714)
#3 threaded_lazy_init_name_hash name-hash.c:526 (test-lazy-init-name-hash+0x00000043d714)
#4 lazy_init_name_hash name-hash.c:588 (test-lazy-init-name-hash+0x00000043d714)
#5 lazy_init_name_hash name-hash.c:581 (test-lazy-init-name-hash+0x00000043ec34)
#6 test_lazy_init_name_hash name-hash.c:613 (test-lazy-init-name-hash+0x00000043ec34)
#7 time_runs t/helper/test-lazy-init-name-hash.c:74 (test-lazy-init-name-hash+0x000000405ac2)
#8 cmd_main t/helper/test-lazy-init-name-hash.c:261 (test-lazy-init-name-hash+0x0000004066c1)
#9 main common-main.c:43 (test-lazy-init-name-hash+0x000000404f91)
Mutex M31 (0x7d640001a810) created at:
#0 pthread_mutex_init <null> (libtsan.so.0+0x0000000280b5)
#1 init_recursive_mutex thread-utils.c:73 (test-lazy-init-name-hash+0x0000004d829b)
#2 init_dir_mutex name-hash.c:241 (test-lazy-init-name-hash+0x00000043d714)
#3 threaded_lazy_init_name_hash name-hash.c:526 (test-lazy-init-name-hash+0x00000043d714)
#4 lazy_init_name_hash name-hash.c:588 (test-lazy-init-name-hash+0x00000043d714)
#5 lazy_init_name_hash name-hash.c:581 (test-lazy-init-name-hash+0x00000043ec34)
#6 test_lazy_init_name_hash name-hash.c:613 (test-lazy-init-name-hash+0x00000043ec34)
#7 time_runs t/helper/test-lazy-init-name-hash.c:74 (test-lazy-init-name-hash+0x000000405ac2)
#8 cmd_main t/helper/test-lazy-init-name-hash.c:261 (test-lazy-init-name-hash+0x0000004066c1)
#9 main common-main.c:43 (test-lazy-init-name-hash+0x000000404f91)
Thread T2 (tid=10557, running) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 threaded_lazy_init_name_hash name-hash.c:541 (test-lazy-init-name-hash+0x00000043d7ab)
#2 lazy_init_name_hash name-hash.c:588 (test-lazy-init-name-hash+0x00000043d7ab)
#3 lazy_init_name_hash name-hash.c:581 (test-lazy-init-name-hash+0x00000043ec34)
#4 test_lazy_init_name_hash name-hash.c:613 (test-lazy-init-name-hash+0x00000043ec34)
#5 time_runs t/helper/test-lazy-init-name-hash.c:74 (test-lazy-init-name-hash+0x000000405ac2)
#6 cmd_main t/helper/test-lazy-init-name-hash.c:261 (test-lazy-init-name-hash+0x0000004066c1)
#7 main common-main.c:43 (test-lazy-init-name-hash+0x000000404f91)
Thread T1 (tid=10556, finished) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 threaded_lazy_init_name_hash name-hash.c:541 (test-lazy-init-name-hash+0x00000043d7ab)
#2 lazy_init_name_hash name-hash.c:588 (test-lazy-init-name-hash+0x00000043d7ab)
#3 lazy_init_name_hash name-hash.c:581 (test-lazy-init-name-hash+0x00000043ec34)
#4 test_lazy_init_name_hash name-hash.c:613 (test-lazy-init-name-hash+0x00000043ec34)
#5 time_runs t/helper/test-lazy-init-name-hash.c:74 (test-lazy-init-name-hash+0x000000405ac2)
#6 cmd_main t/helper/test-lazy-init-name-hash.c:261 (test-lazy-init-name-hash+0x0000004066c1)
#7 main common-main.c:43 (test-lazy-init-name-hash+0x000000404f91)
SUMMARY: ThreadSanitizer: data race hashmap.c:209 hashmap_add
