From: Jinshan Xiong <jinshan.xi...@intel.com> 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.xi...@intel.com> Reviewed-on: http://review.whamcloud.com/9881 Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4558 Reviewed-by: Bobi Jam <bobi...@gmail.com> Reviewed-by: Lai Siyao <lai.si...@intel.com> Signed-off-by: Oleg Drokin <oleg.dro...@intel.com> --- drivers/staging/lustre/lustre/obdclass/cl_lock.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/staging/lustre/lustre/obdclass/cl_lock.c b/drivers/staging/lustre/lustre/obdclass/cl_lock.c index 918f433..f8040a8 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(). -- 1.8.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
