akpm at linux-foundation.org
2014-Aug-06 20:32 UTC
[Ocfs2-devel] [patch 08/10] ocfs2/dlm: fix race between dispatched_work and dlm_lockres_grab_inflight_worker
From: Joseph Qi <joseph.qi at huawei.com> Subject: ocfs2/dlm: fix race between dispatched_work and dlm_lockres_grab_inflight_worker ac4fef4d23ed ("ocfs2/dlm: do not purge lockres that is queued for assert master") may have the following possible race case: dlm_dispatch_assert_master dlm_wq =======================================================================queue_work(dlm->quedlm_worker, &dlm->dispatched_work); dispatch work, dlm_lockres_drop_inflight_worker *BUG_ON(res->inflight_assert_workers == 0)* dlm_lockres_grab_inflight_worker inflight_assert_workers++ So ensure inflight_assert_workers to be increased first. Signed-off-by: Joseph Qi <joseph.qi at huawei.com> Signed-off-by: Xue jiufei <xuejiufei at huawei.com> Cc: Joel Becker <jlbec at evilplan.org> Cc: Mark Fasheh <mfasheh at suse.com> Signed-off-by: Andrew Morton <akpm at linux-foundation.org> --- fs/ocfs2/dlm/dlmmaster.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff -puN fs/ocfs2/dlm/dlmmaster.c~ocfs2-dlm-fix-race-between-dispatched_work-and-dlm_lockres_grab_inflight_worker fs/ocfs2/dlm/dlmmaster.c --- a/fs/ocfs2/dlm/dlmmaster.c~ocfs2-dlm-fix-race-between-dispatched_work-and-dlm_lockres_grab_inflight_worker +++ a/fs/ocfs2/dlm/dlmmaster.c @@ -684,14 +684,6 @@ void __dlm_lockres_grab_inflight_worker( res->inflight_assert_workers); } -static void dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm, - struct dlm_lock_resource *res) -{ - spin_lock(&res->spinlock); - __dlm_lockres_grab_inflight_worker(dlm, res); - spin_unlock(&res->spinlock); -} - static void __dlm_lockres_drop_inflight_worker(struct dlm_ctxt *dlm, struct dlm_lock_resource *res) { @@ -1625,6 +1617,7 @@ send_response: } mlog(0, "%u is the owner of %.*s, cleaning everyone else\n", dlm->node_num, res->lockname.len, res->lockname.name); + spin_lock(&res->spinlock); ret = dlm_dispatch_assert_master(dlm, res, 0, request->node_idx, DLM_ASSERT_MASTER_MLE_CLEANUP); if (ret < 0) { @@ -1632,7 +1625,8 @@ send_response: response = DLM_MASTER_RESP_ERROR; dlm_lockres_put(res); } else - dlm_lockres_grab_inflight_worker(dlm, res); + __dlm_lockres_grab_inflight_worker(dlm, res); + spin_unlock(&res->spinlock); } else { if (res) dlm_lockres_put(res); _