Hello Peng Tao,
The patch d7e09d0397e8: "staging: add Lustre file system client
support" from May 2, 2013, leads to the following static checker
warning:
drivers/staging/lustre/lustre/obdecho/echo_client.c:1040 cl_echo_enqueue0()
error: 'lck' dereferencing possible ERR_PTR()
drivers/staging/lustre/lustre/obdecho/echo_client.c
1034
1035 lck = cl_lock_request(env, io, descr, "ec enqueue", eco);
^^^^^^^^^^^^^^^
This can return either an ERR_PTR or NULL. It's not clear from the
documentation what that means. There is actually some documentation
for this function though so that's good.
1036 if (lck) {
^^^
Ugh. Success handling.
1037 struct echo_client_obd *ec = eco->eo_dev->ed_ec;
1038 struct echo_lock *el;
1039
1040 rc = cl_wait(env, lck);
1041 if (rc == 0) {
^^^^^^^
More success handling and nested indents. If we flip these around to
test for failure instead the code becomes much clearer.
1042 el = cl2echo_lock(cl_lock_at(lck, &echo_device_type));
1043 spin_lock(&ec->ec_lock);
1044 if (list_empty(&el->el_chain)) {
1045 list_add(&el->el_chain, &ec->ec_locks);
1046 el->el_cookie = ++ec->ec_unique;
1047 }
1048 atomic_inc(&el->el_refcount);
1049 *cookie = el->el_cookie;
1050 spin_unlock(&ec->ec_lock);
1051 } else {
1052 cl_lock_release(env, lck, "ec enqueue", current);
1053 }
1054 }
1055 return rc;
1056 }
regards,
dan carpenter
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