diff options
| author | Jinshan Xiong <jinshan.xiong@intel.com> | 2014-04-27 13:07:03 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-04-27 10:31:00 -0700 |
| commit | 8d67c821d96c8cfaa2ae05f346f1b2a07f0c15ec (patch) | |
| tree | 487786c68fe411be1ed3a88d68911cce06adc963 | |
| parent | 4de665c1b308c256c0c32f950afe350b8c153583 (diff) | |
staging/lustre/clio: Solve a race in cl_lock_put
It's not atomic to check the last reference and state of cl_lock
in cl_lock_put(). This can cause a problem that an using lock is
freed, if the process is preempted between atomic_dec_and_test()
and (lock->cll_state == CLS_FREEING).
This problem can be solved by holding a refcount by coh_locks. In
this case, it can be sure that if the lock refcount reaches zero,
nobody else can have any chance to use it again.
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-on: http://review.whamcloud.com/9881
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4558
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/lustre/lustre/obdclass/cl_lock.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_lock.c b/drivers/staging/lustre/lustre/obdclass/cl_lock.c index 918f433b22d9..f8040a8923b2 100644 --- a/drivers/staging/lustre/lustre/obdclass/cl_lock.c +++ b/drivers/staging/lustre/lustre/obdclass/cl_lock.c @@ -533,6 +533,7 @@ static struct cl_lock *cl_lock_find(const struct lu_env *env, spin_lock(&head->coh_lock_guard); ghost = cl_lock_lookup(env, obj, io, need); if (ghost == NULL) { + cl_lock_get_trust(lock); list_add_tail(&lock->cll_linkage, &head->coh_locks); spin_unlock(&head->coh_lock_guard); @@ -791,15 +792,22 @@ static void cl_lock_delete0(const struct lu_env *env, struct cl_lock *lock) LINVRNT(cl_lock_invariant(env, lock)); if (lock->cll_state < CLS_FREEING) { + bool in_cache; + LASSERT(lock->cll_state != CLS_INTRANSIT); cl_lock_state_set(env, lock, CLS_FREEING); head = cl_object_header(lock->cll_descr.cld_obj); spin_lock(&head->coh_lock_guard); - list_del_init(&lock->cll_linkage); + in_cache = !list_empty(&lock->cll_linkage); + if (in_cache) + list_del_init(&lock->cll_linkage); spin_unlock(&head->coh_lock_guard); + if (in_cache) /* coh_locks cache holds a refcount. */ + cl_lock_put(env, lock); + /* * From now on, no new references to this lock can be acquired * by cl_lock_lookup(). |