From 91151228065354a050fd0d190aefdd662a0580aa Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Thu, 14 Nov 2013 12:56:18 +0100 Subject: workqueue: swap set_cpus_allowed_ptr() and PF_NO_SETAFFINITY Move the setting of PF_NO_SETAFFINITY up before set_cpus_allowed() in create_worker(). Otherwise userland can change ->cpus_allowed in between. Signed-off-by: Oleg Nesterov Signed-off-by: Tejun Heo diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 987293d..f894242 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1736,16 +1736,17 @@ static struct worker *create_worker(struct worker_pool *pool) if (IS_ERR(worker->task)) goto fail; + set_user_nice(worker->task, pool->attrs->nice); + + /* prevent userland from meddling with cpumask of workqueue workers */ + worker->task->flags |= PF_NO_SETAFFINITY; + /* * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any * online CPUs. It'll be re-applied when any of the CPUs come up. */ - set_user_nice(worker->task, pool->attrs->nice); set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); - /* prevent userland from meddling with cpumask of workqueue workers */ - worker->task->flags |= PF_NO_SETAFFINITY; - /* * The caller is responsible for ensuring %POOL_DISASSOCIATED * remains stable across this function. See the comments above the -- cgit v0.10.2 From 8a2b75384444488fc4f2cbb9f0921b6a0794838f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Sep 2013 12:30:04 -0400 Subject: workqueue: fix ordered workqueues in NUMA setups An ordered workqueue implements execution ordering by using single pool_workqueue with max_active == 1. On a given pool_workqueue, work items are processed in FIFO order and limiting max_active to 1 enforces the queued work items to be processed one by one. Unfortunately, 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues") accidentally broke this guarantee by applying NUMA affinity to ordered workqueues too. On NUMA setups, an ordered workqueue would end up with separate pool_workqueues for different nodes. Each pool_workqueue still limits max_active to 1 but multiple work items may be executed concurrently and out of order depending on which node they are queued to. Fix it by using dedicated ordered_wq_attrs[] when creating ordered workqueues. The new attrs match the unbound ones except that no_numa is always set thus forcing all NUMA nodes to share the default pool_workqueue. While at it, add sanity check in workqueue creation path which verifies that an ordered workqueues has only the default pool_workqueue. Signed-off-by: Tejun Heo Reported-by: Libin Cc: stable@vger.kernel.org Cc: Lai Jiangshan diff --git a/kernel/workqueue.c b/kernel/workqueue.c index f894242..bbb5e98 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -305,6 +305,9 @@ static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); /* I: attributes used when instantiating standard unbound pools on demand */ static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; +/* I: attributes used when instantiating ordered pools on demand */ +static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; + struct workqueue_struct *system_wq __read_mostly; EXPORT_SYMBOL(system_wq); struct workqueue_struct *system_highpri_wq __read_mostly; @@ -4107,7 +4110,7 @@ out_unlock: static int alloc_and_link_pwqs(struct workqueue_struct *wq) { bool highpri = wq->flags & WQ_HIGHPRI; - int cpu; + int cpu, ret; if (!(wq->flags & WQ_UNBOUND)) { wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); @@ -4127,6 +4130,13 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq) mutex_unlock(&wq->mutex); } return 0; + } else if (wq->flags & __WQ_ORDERED) { + ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]); + /* there should only be single pwq for ordering guarantee */ + WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || + wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), + "ordering guarantee broken for workqueue %s\n", wq->name); + return ret; } else { return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); } @@ -5052,13 +5062,23 @@ static int __init init_workqueues(void) } } - /* create default unbound wq attrs */ + /* create default unbound and ordered wq attrs */ for (i = 0; i < NR_STD_WORKER_POOLS; i++) { struct workqueue_attrs *attrs; BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL))); attrs->nice = std_nice[i]; unbound_std_wq_attrs[i] = attrs; + + /* + * An ordered wq should have only one pwq as ordering is + * guaranteed by max_active which is enforced by pwqs. + * Turn off NUMA so that dfl_pwq is used for all nodes. + */ + BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL))); + attrs->nice = std_nice[i]; + attrs->no_numa = true; + ordered_wq_attrs[i] = attrs; } system_wq = alloc_workqueue("events", 0, 0); -- cgit v0.10.2 From 9ef28a73ff6a1598d6f915973c282fe28291f800 Mon Sep 17 00:00:00 2001 From: Li Bin Date: Mon, 9 Sep 2013 13:13:58 +0800 Subject: workqueue: fix comment typo for __queue_work() It seems the "dying" should be "draining" here. Signed-off-by: Li Bin Signed-off-by: Tejun Heo diff --git a/kernel/workqueue.c b/kernel/workqueue.c index bbb5e98..73bdf3c 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1323,7 +1323,7 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, debug_work_activate(work); - /* if dying, only works from the same workqueue are allowed */ + /* if draining, only works from the same workqueue are allowed */ if (unlikely(wq->flags & __WQ_DRAINING) && WARN_ON_ONCE(!is_chained_work(wq))) return; -- cgit v0.10.2 From 4e8b22bd1a37447712f1b1d96352fc53b463c6b3 Mon Sep 17 00:00:00 2001 From: Li Bin Date: Tue, 10 Sep 2013 09:52:35 +0800 Subject: workqueue: fix pool ID allocation leakage and remove BUILD_BUG_ON() in init_workqueues When one work starts execution, the high bits of work's data contain pool ID. It can represent a maximum of WORK_OFFQ_POOL_NONE. Pool ID is assigned WORK_OFFQ_POOL_NONE when the work being initialized indicating that no pool is associated and get_work_pool() uses it to check the associated pool. So if worker_pool_assign_id() assigns a ID greater than or equal WORK_OFFQ_POOL_NONE to a pool, it triggers leakage, and it may break the non-reentrance guarantee. This patch fix this issue by modifying the worker_pool_assign_id() function calling idr_alloc() by setting @end param WORK_OFFQ_POOL_NONE. Furthermore, in the current implementation, the BUILD_BUG_ON() in init_workqueues makes no sense. The number of worker pools needed cannot be determined at compile time, because the number of backing pools for UNBOUND workqueues is dynamic based on the assigned custom attributes. So remove it. tj: Minor comment and indentation updates. Signed-off-by: Li Bin Signed-off-by: Tejun Heo diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 73bdf3c..c66912be 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -521,14 +521,21 @@ static inline void debug_work_activate(struct work_struct *work) { } static inline void debug_work_deactivate(struct work_struct *work) { } #endif -/* allocate ID and assign it to @pool */ +/** + * worker_pool_assign_id - allocate ID and assing it to @pool + * @pool: the pool pointer of interest + * + * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned + * successfully, -errno on failure. + */ static int worker_pool_assign_id(struct worker_pool *pool) { int ret; lockdep_assert_held(&wq_pool_mutex); - ret = idr_alloc(&worker_pool_idr, pool, 0, 0, GFP_KERNEL); + ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, + GFP_KERNEL); if (ret >= 0) { pool->id = ret; return 0; @@ -5020,10 +5027,6 @@ static int __init init_workqueues(void) int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; int i, cpu; - /* make sure we have enough bits for OFFQ pool ID */ - BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) < - WORK_CPU_END * NR_STD_WORKER_POOLS); - WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); -- cgit v0.10.2