URL: https://github.com/SSSD/sssd/pull/947
Title: #947: tests: fix race conditions in integration tests
pbrezina commented:
"""
> I. `test_files_provider.py`
>
> > `poll_canary` has no meaning as we currently block when refreshing the
> > cache. We can either remove it or report a bug against sssd that it behaves
> > incorrectly. @jhrozek When files provider is updating cache in inotify
> > callback (i.e. domain is inconsistent) should nss responder A) return not
> > found and let client look in files database, or B) block until the cache is
> > updated? Currently B is true but tests says A should be done.
>
> Actually... Are you sure "B is true"?
> I just tested with a patch of `providers/files/files_ops.c:sf_passwd_cb()`:
> `+ while (1) { usleep(100000); }`
> right before `sf_enum_files()` and `id` works fine (according to your
> statement this should block).
I'm sure. See:
*
https://github.com/SSSD/sssd/blob/master/src/responder/common/responder_dp.c#L44
* https://github.com/SSSD/sssd/blob/master/src/providers/files/files_id.c#L132
* https://github.com/SSSD/sssd/blob/master/src/providers/files/files_ops.c#L841
> I checked with `strace`:
>
> ```
> openat(AT_FDCWD, "/lib64/libnss_sss.so.2", O_RDONLY|O_CLOEXEC) = 3
> openat(AT_FDCWD, "/var/lib/sss/mc/passwd", O_RDONLY|O_CLOEXEC) = 3
> connect(4, {sa_family=AF_UNIX, sun_path="/var/lib/sss/pipes/nss"}, 110) = 0
> openat(AT_FDCWD, "/lib64/libnss_files.so.2", O_RDONLY|O_CLOEXEC) = 5
> ```
Because you used `usleep` at wrong place. See, D-Bus communication is
asynchronous so once you put a sleep somewhere, the process can not receive nor
send any message. In this case, even though `dp_sbus_domain_inconsistent` was
called, the message was not send because you immediately go to sleep.
Therefore, the nss responder will answer with what it has in cache. You will
see this in logs.
I'm not sure why it continues with nss_files, I am not this much familiar with
nss internals.
To reproduce it correctly, use rather this diff:
```diff
--- a/src/providers/files/files_ops.c
+++ b/src/providers/files/files_ops.c
@@ -836,9 +836,9 @@ static int sf_passwd_cb(const char *filename, uint32_t
flags, void *pvt)
ret = EOK;
done:
- id_ctx->updating_passwd = false;
+ // id_ctx->updating_passwd = false;
sf_cb_done(id_ctx);
- files_account_info_finished(id_ctx, BE_REQ_USER, ret);
+ // files_account_info_finished(id_ctx, BE_REQ_USER, ret);
return ret;
}
```
```
[root /dev/shm/sssd]# id pbrezina@files
uid=1000(pbrezina) gid=1000(pbrezina) groups=1000(pbrezina),10(wheel)
[root /dev/shm/sssd]# touch /etc/passwd
[root /dev/shm/sssd]# sss_cache -E
[root /dev/shm/sssd]# id pbrezina@files
... after a long timeout
id: ‘pbrezina@files’: no such user
[root /dev/shm/sssd]# id pbrezina
uid=1000(pbrezina) gid=1000(pbrezina) groups=1000(pbrezina),10(wheel)
[root /dev/shm/sssd]# touch /etc/passwd
[root /dev/shm/sssd]# sss_cache -E
[root /dev/shm/sssd]# id pbrezina
... after a long timeout
uid=1000(pbrezina) gid=1000(pbrezina) groups=1000(pbrezina),10(wheel)
```
"""
See the full comment at
https://github.com/SSSD/sssd/pull/947#issuecomment-562093538
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