Messages in this thread | ![/](/images/icornerl.gif) | | From | Dawson Engler <> | Subject | [CHECKER] deadlock in 2.5.62/fs/lockd/svc*.c? | Date | Sat, 22 Mar 2003 02:10:28 -0800 (PST) |
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Hi All,
here's a more interesting potential deadlock in the 2.5.62/fs/lockd/svc*.c code that requires the miscordination of three threads. It might be a false because of 1. infeasible callchain path or
2. the two struct nlm_file.f_sema pointers cannot actually point to the same object.
It requires three threads: thread 1: acquires nlm_file_sema then tries to get file->f_sema thread 2: acquires file->f_sema and tries to get nlm_host_sema thread 3: acquires nlm_host_sema and tries to get nlm_file_sema
Any feedback on this one would be great.
Dawson
BUG: ERROR: 3 thread global-global deadlock. <&nlm_file_sema>-><&nlm_host_sema> occurred 4 times <&nlm_host_sema>-><&nlm_file_sema> occurred 5 times
Plausible chain thread 1: <&nlm_file_sema,struct nlm_file.f_sema> depth = 3: 2.5.62/fs/lockd/svcsubs.c:nlm_traverse_files:218
down(&nlm_file_sema);
->2.5.62/fs/lockd/svcsubs.c:nlm_traverse_files:218 ->nlm_traverse_files:224 ->nlm_inspect_file:202 ->end=fs/lockd/svclock.c:nlmsvc_traverse_blocks:274:down
down(&file->f_sema);
Seems like a plausible chain. thread 2: <struct nlm_file.f_sema,&nlm_host_sema> depth = 4: 2.5.62/fs/lockd/svclock.c:nlmsvc_lock:309
/* Lock file against concurrent access */ down(&file->f_sema);
->2.5.62/fs/lockd/svclock.c:nlmsvc_lock:309 ->nlmsvc_lock:351 ->nlmsvc_create_block:179 ->2.5.62/fs/lockd/host.c:nlmclnt_lookup_host:44 ->end=nlm_lookup_host:74:down
/* Lock hash table */ down(&nlm_host_sema);
Seems reasonable. <&nlm_host_sema>-><&nlm_file_sema> = depth = 4: 2.5.62/fs/lockd/host.c:nlm_lookup_host:74 /* Lock hash table */ down(&nlm_host_sema);
->2.5.62/fs/lockd/host.c:nlm_lookup_host:74 ->nlm_lookup_host:77 ->nlm_gc_hosts:319 ->/u2/engler/mc/oses/linux/linux-2.5.62/fs/lockd/svcsubs.c:nlmsvc_mark_resources:279 ->end=nlm_traverse_files:218:down ->2.5.62/fs/lockd/svcsubs.c:nlm_traverse_files:218
down(&nlm_file_sema);
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