From: Valeriy Vdovin <valeriy.vdo...@virtuozzo.com> Per-ve workqueue is started at ve cgroup start before ve->is_running is set to true, it is stopped at ve cgroup stop after ve->is_running is set to false and is guarded via synchronize_rcu, stop also implies waiting for all queued and yet unfinished works to finish.
So the user of ve->wq should take rcu_read_lock, under the lock check ve->is_running, if ve->is_running is true user can safely queue_work on the workqueue and release the lock. We need per-ve workqueue for per-ve release-agent implementation. Release-agent code (in next patches) would use call_usermodehelper_ve from per-ve workqueue worker to run the release-agent binary in actual ve-context, so that workqueue is started after umh started and stopped before umh kthread stopped. Short history of the patch: https://jira.sw.ru/browse/PSBM-83887 Signed-off-by: Valeriy Vdovin <valeriy.vdo...@virtuozzo.com> Reviewed-by: Kirill Tkhai <ktk...@virtuozzo.com> (cherry picked from vz7 commit 0293870666c4f96bd56f612d94f560626c76e2fd) https://jira.sw.ru/browse/PSBM-108270 (cherry picked from vz8 commit 58b7b3bb335b2bafca9caccfee8c435242baa664) +++ cgroup/ve: Do not run release_agent on non-running ve +++ cgroup/ve: Move ve workqueue stop to ve_stop_ns() (cherry picked from vz8 commit 1481d130afa32eecffe28b34fd00b57e11d2666f) vz9 changes: - merge per-ve workqueue fixes from 1481d130afa3 - add comment to wq field about syncronization using rcu and is_running https://jira.sw.ru/browse/PSBM-134002 Signed-off-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com> --- include/linux/ve.h | 3 +++ kernel/ve/ve.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+) diff --git a/include/linux/ve.h b/include/linux/ve.h index d3499853e6dd..474863746a48 100644 --- a/include/linux/ve.h +++ b/include/linux/ve.h @@ -104,6 +104,9 @@ struct ve_struct { unsigned long aio_nr; unsigned long aio_max_nr; #endif + /* Should take rcu_read_lock and check ve->is_running before queue */ + struct workqueue_struct *wq; + struct vfsmount *devtmpfs_mnt; }; diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c index 827c6089a4c3..30ace4a07568 100644 --- a/kernel/ve/ve.c +++ b/kernel/ve/ve.c @@ -460,6 +460,22 @@ static int ve_start_kthreadd(struct ve_struct *ve) return err; } +static int ve_workqueue_start(struct ve_struct *ve) +{ + ve->wq = alloc_workqueue("ve_wq_%s", WQ_SYSFS|WQ_FREEZABLE|WQ_UNBOUND, + 8, ve->ve_name); + + if (!ve->wq) + return -ENOMEM; + return 0; +} + +static void ve_workqueue_stop(struct ve_struct *ve) +{ + destroy_workqueue(ve->wq); + ve->wq = NULL; +} + /* under ve->op_sem write-lock */ static int ve_start_container(struct ve_struct *ve) { @@ -504,6 +520,10 @@ static int ve_start_container(struct ve_struct *ve) if (err) goto err_umh; + err = ve_workqueue_start(ve); + if (err) + goto err_workqueue; + err = ve_hook_iterate_init(VE_SS_CHAIN, ve); if (err < 0) goto err_iterate; @@ -523,6 +543,8 @@ static int ve_start_container(struct ve_struct *ve) err_mark_ve: ve_hook_iterate_fini(VE_SS_CHAIN, ve); err_iterate: + ve_workqueue_stop(ve); +err_workqueue: ve_stop_umh(ve); err_umh: ve_stop_kthreadd(ve); @@ -552,6 +574,14 @@ void ve_stop_ns(struct pid_namespace *pid_ns) * ve_mutex works as barrier for ve_can_attach(). */ ve->is_running = 0; + synchronize_rcu(); + + /* + * release_agent works on top of umh_worker, so we must make sure, that + * ve workqueue is stopped first. + */ + ve_workqueue_stop(ve); + /* * Neither it can be in pseudosuper state * anymore, setup it again if needed. @@ -1531,6 +1561,8 @@ static int __init ve_subsys_init(void) { ve_cachep = KMEM_CACHE_USERCOPY(ve_struct, SLAB_PANIC, core_pattern); list_add(&ve0.ve_list, &ve_list_head); + ve0.wq = alloc_workqueue("ve0_wq", WQ_FREEZABLE|WQ_UNBOUND, 8); + BUG_ON(!ve0.wq); return 0; } late_initcall(ve_subsys_init); -- 2.31.1 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
