Hello Yan, Zheng,
This is a semi-automatic email about new static checker warnings.
The patch ed9b430c9ba9: "ceph: cleanup ceph_flush_snaps()" from Jul
5, 2016, leads to the following Smatch complaint:
fs/ceph/caps.c:1387 ceph_flush_snaps()
warn: variable dereferenced before check 'psession' (see line 1350)
fs/ceph/caps.c
1349 struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
1350 struct ceph_mds_session *session = *psession;
^^^^^^^^^
New code assume psession can't be NULL.
1351 int mds;
1352 dout("ceph_flush_snaps %p\n", inode);
1353 retry:
1354 spin_lock(&ci->i_ceph_lock);
1355 if (!(ci->i_ceph_flags & CEPH_I_FLUSH_SNAPS)) {
1356 dout(" no capsnap needs flush, doing nothing\n");
1357 goto out;
1358 }
1359 if (!ci->i_auth_cap) {
1360 dout(" no auth cap (migrating?), doing nothing\n");
1361 goto out;
1362 }
1363
1364 mds = ci->i_auth_cap->session->s_mds;
1365 if (session && session->s_mds != mds) {
1366 dout(" oops, wrong session %p mutex\n", session);
1367 mutex_unlock(&session->s_mutex);
1368 ceph_put_mds_session(session);
1369 session = NULL;
1370 }
1371 if (!session) {
1372 spin_unlock(&ci->i_ceph_lock);
1373 mutex_lock(&mdsc->mutex);
1374 session = __ceph_lookup_mds_session(mdsc, mds);
1375 mutex_unlock(&mdsc->mutex);
1376 if (session) {
1377 dout(" inverting session/ino locks on %p\n", session);
1378 mutex_lock(&session->s_mutex);
1379 }
1380 goto retry;
1381 }
1382
1383 __ceph_flush_snaps(ci, session);
1384 out:
1385 spin_unlock(&ci->i_ceph_lock);
1386
1387 if (psession) {
^^^^^^^^
Old code assumed it could be.
1388 *psession = session;
1389 } else {
regards,
dan carpenter
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