user/sven/linux.git/include/linux/workqueue.h, branch v3.10.44

workqueue: include workqueue info when printing debug dump of a worker task

2013-05-01T00:04:02Z

One of the problems that arise when converting dedicated custom threadpool to workqueue is that the shared worker pool used by workqueue anonimizes each worker making it more difficult to identify what the worker was doing on which target from the output of sysrq-t or debug dump from oops, BUG() and friends. This patch implements set_worker_desc() which can be called from any workqueue work function to set its description. When the worker task is dumped for whatever reason - sysrq-t, WARN, BUG, oops, lockdep assertion and so on - the description will be printed out together with the workqueue name and the worker function pointer. The printing side is implemented by print_worker_info() which is called from functions in task dump paths - sched_show_task() and dump_stack_print_info(). print_worker_info() can be safely called on any task in any state as long as the task struct itself is accessible. It uses probe_*() functions to access worker fields. It may print garbage if something went very wrong, but it wouldn't cause (another) oops. The description is currently limited to 24bytes including the terminating \0. worker->desc_valid and workder->desc[] are added and the 64 bytes marker which was already incorrect before adding the new fields is moved to the correct position. Here's an example dump with writeback updated to set the bdi name as worker desc. Hardware name: Bochs Modules linked in: Pid: 7, comm: kworker/u9:0 Not tainted 3.9.0-rc1-work+ #1 Workqueue: writeback bdi_writeback_workfn (flush-8:0) ffffffff820a3ab0 ffff88000f6e9cb8 ffffffff81c61845 ffff88000f6e9cf8 ffffffff8108f50f 0000000000000000 0000000000000000 ffff88000cde16b0 ffff88000cde1aa8 ffff88001ee19240 ffff88000f6e9fd8 ffff88000f6e9d08 Call Trace: [] dump_stack+0x19/0x1b [] warn_slowpath_common+0x7f/0xc0 [] warn_slowpath_null+0x1a/0x20 [] bdi_writeback_workfn+0x2a0/0x3b0 ... Signed-off-by: Tejun Heo Cc: Peter Zijlstra Cc: Ingo Molnar Acked-by: Jan Kara Cc: Oleg Nesterov Cc: Jens Axboe Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

workqueue: update sysfs interface to reflect NUMA awareness and a kernel param to disable NUMA affinity

2013-04-01T18:23:38Z

Unbound workqueues are now NUMA aware. Let's add some control knobs and update sysfs interface accordingly. * Add kernel param workqueue.numa_disable which disables NUMA affinity globally. * Replace sysfs file "pool_id" with "pool_ids" which contain node:pool_id pairs. This change is userland-visible but "pool_id" hasn't seen a release yet, so this is okay. * Add a new sysf files "numa" which can toggle NUMA affinity on individual workqueues. This is implemented as attrs->no_numa whichn is special in that it isn't part of a pool's attributes. It only affects how apply_workqueue_attrs() picks which pools to use. After "pool_ids" change, first_pwq() doesn't have any user left. Removed. Signed-off-by: Tejun Heo Reviewed-by: Lai Jiangshan

workqueue: inline trivial wrappers

2013-03-13T23:51:36Z

There's no reason to make these trivial wrappers full (exported) functions. Inline the followings. queue_work() queue_delayed_work() mod_delayed_work() schedule_work_on() schedule_work() schedule_delayed_work_on() schedule_delayed_work() keventd_up() Signed-off-by: Tejun Heo

workqueue: implement current_is_workqueue_rescuer()

2013-03-13T00:42:01Z

Implement a function which queries whether it currently is running off a workqueue rescuer. This will be used to convert writeback to workqueue. Signed-off-by: Tejun Heo

workqueue: implement sysfs interface for workqueues

2013-03-12T18:37:07Z

There are cases where workqueue users want to expose control knobs to userland. e.g. Unbound workqueues with custom attributes are scheduled to be used for writeback workers and depending on configuration it can be useful to allow admins to tinker with the priority or allowed CPUs. This patch implements workqueue_sysfs_register(), which makes the workqueue visible under /sys/bus/workqueue/devices/WQ_NAME. There currently are two attributes common to both per-cpu and unbound pools and extra attributes for unbound pools including nice level and cpumask. If alloc_workqueue*() is called with WQ_SYSFS, workqueue_sysfs_register() is called automatically as part of workqueue creation. This is the preferred method unless the workqueue user wants to apply workqueue_attrs before making the workqueue visible to userland. v2: Disallow exposing ordered workqueues as ordered workqueues can't be tuned in any way. Signed-off-by: Tejun Heo

workqueue: reject adjusting max_active or applying attrs to ordered workqueues

2013-03-12T18:30:04Z

Adjusting max_active of or applying new workqueue_attrs to an ordered workqueue breaks its ordering guarantee. The former is obvious. The latter is because applying attrs creates a new pwq (pool_workqueue) and there is no ordering constraint between the old and new pwqs. Make apply_workqueue_attrs() and workqueue_set_max_active() trigger WARN_ON() if those operations are requested on an ordered workqueue and fail / ignore respectively. Signed-off-by: Tejun Heo Reviewed-by: Lai Jiangshan

workqueue: make it clear that WQ_DRAINING is an internal flag

2013-03-12T18:30:04Z

We're gonna add another internal WQ flag. Let's make the distinction clear. Prefix WQ_DRAINING with __ and move it to bit 16. Signed-off-by: Tejun Heo Reviewed-by: Lai Jiangshan

workqueue: implement apply_workqueue_attrs()

2013-03-12T18:30:04Z

Implement apply_workqueue_attrs() which applies workqueue_attrs to the specified unbound workqueue by creating a new pwq (pool_workqueue) linked to worker_pool with the specified attributes. A new pwq is linked at the head of wq->pwqs instead of tail and __queue_work() verifies that the first unbound pwq has positive refcnt before choosing it for the actual queueing. This is to cover the case where creation of a new pwq races with queueing. As base ref on a pwq won't be dropped without making another pwq the first one, __queue_work() is guaranteed to make progress and not add work item to a dead pwq. init_and_link_pwq() is updated to return the last first pwq the new pwq replaced, which is put by apply_workqueue_attrs(). Note that apply_workqueue_attrs() is almost identical to unbound pwq part of alloc_and_link_pwqs(). The only difference is that there is no previous first pwq. apply_workqueue_attrs() is implemented to handle such cases and replaces unbound pwq handling in alloc_and_link_pwqs(). Signed-off-by: Tejun Heo Reviewed-by: Lai Jiangshan

workqueue: drop WQ_RESCUER and test workqueue->rescuer for NULL instead

2013-03-12T18:30:03Z

WQ_RESCUER is superflous. WQ_MEM_RECLAIM indicates that the user wants a rescuer and testing wq->rescuer for NULL can answer whether a given workqueue has a rescuer or not. Drop WQ_RESCUER and test wq->rescuer directly. This will help simplifying __alloc_workqueue_key() failure path by allowing it to use destroy_workqueue() on a partially constructed workqueue, which in turn will help implementing dynamic management of pool_workqueues. While at it, clear wq->rescuer after freeing it in destroy_workqueue(). This is a precaution as scheduled changes will make destruction more complex. This patch doesn't introduce any functional changes. Signed-off-by: Tejun Heo Reviewed-by: Lai Jiangshan

workqueue: introduce workqueue_attrs

2013-03-12T18:30:00Z

Introduce struct workqueue_attrs which carries worker attributes - currently the nice level and allowed cpumask along with helper routines alloc_workqueue_attrs() and free_workqueue_attrs(). Each worker_pool now carries ->attrs describing the attributes of its workers. All functions dealing with cpumask and nice level of workers are updated to follow worker_pool->attrs instead of determining them from other characteristics of the worker_pool, and init_workqueues() is updated to set worker_pool->attrs appropriately for all standard pools. Note that create_worker() is updated to always perform set_user_nice() and use set_cpus_allowed_ptr() combined with manual assertion of PF_THREAD_BOUND instead of kthread_bind(). This simplifies handling random attributes without affecting the outcome. This patch doesn't introduce any behavior changes. v2: Missing cpumask_var_t definition caused build failure on some archs. linux/cpumask.h included. Signed-off-by: Tejun Heo Reported-by: kbuild test robot Reviewed-by: Lai Jiangshan