From 3347fa0928210d96aaa2bd6cd5a8391d5e630873 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 16 Sep 2016 15:49:32 -0400 Subject: workqueue: make workqueue available early during boot Workqueue is currently initialized in an early init call; however, there are cases where early boot code has to be split and reordered to come after workqueue initialization or the same code path which makes use of workqueues is used both before workqueue initailization and after. The latter cases have to gate workqueue usages with keventd_up() tests, which is nasty and easy to get wrong. Workqueue usages have become widespread and it'd be a lot more convenient if it can be used very early from boot. This patch splits workqueue initialization into two steps. workqueue_init_early() which sets up the basic data structures so that workqueues can be created and work items queued, and workqueue_init() which actually brings up workqueues online and starts executing queued work items. The former step can be done very early during boot once memory allocation, cpumasks and idr are initialized. The latter right after kthreads become available. This allows work item queueing and canceling from very early boot which is what most of these use cases want. * As systemd_wq being initialized doesn't indicate that workqueue is fully online anymore, update keventd_up() to test wq_online instead. The follow-up patches will get rid of all its usages and the function itself. * Flushing doesn't make sense before workqueue is fully initialized. The flush functions trigger WARN and return immediately before fully online. * Work items are never in-flight before fully online. Canceling can always succeed by skipping the flush step. * Some code paths can no longer assume to be called with irq enabled as irq is disabled during early boot. Use irqsave/restore operations instead. v2: Watchdog init, which requires timer to be running, moved from workqueue_init_early() to workqueue_init(). Signed-off-by: Tejun Heo Suggested-by: Linus Torvalds Link: http://lkml.kernel.org/r/CA+55aFx0vPuMuxn00rBSM192n-Du5uxy+4AvKa0SBSOVJeuCGg@mail.gmail.com --- include/linux/workqueue.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'include/linux/workqueue.h') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 26cc1df280d6..91d416f9c0a7 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -358,6 +358,8 @@ extern struct workqueue_struct *system_freezable_wq; extern struct workqueue_struct *system_power_efficient_wq; extern struct workqueue_struct *system_freezable_power_efficient_wq; +extern bool wq_online; + extern struct workqueue_struct * __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active, struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6); @@ -594,7 +596,7 @@ static inline bool schedule_delayed_work(struct delayed_work *dwork, */ static inline bool keventd_up(void) { - return system_wq != NULL; + return wq_online; } #ifndef CONFIG_SMP @@ -631,4 +633,7 @@ int workqueue_online_cpu(unsigned int cpu); int workqueue_offline_cpu(unsigned int cpu); #endif +int __init workqueue_init_early(void); +int __init workqueue_init(void); + #endif -- cgit v1.2.3-71-gd317 From 863b710b664bdcb90c0c682ee24adb368f497a5b Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 16 Sep 2016 15:49:34 -0400 Subject: workqueue: remove keventd_up() keventd_up() no longer has in-kernel users. Remove it and make wq_online static. Signed-off-by: Tejun Heo --- include/linux/workqueue.h | 10 ---------- kernel/workqueue.c | 2 +- 2 files changed, 1 insertion(+), 11 deletions(-) (limited to 'include/linux/workqueue.h') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 91d416f9c0a7..56417133c672 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -358,8 +358,6 @@ extern struct workqueue_struct *system_freezable_wq; extern struct workqueue_struct *system_power_efficient_wq; extern struct workqueue_struct *system_freezable_power_efficient_wq; -extern bool wq_online; - extern struct workqueue_struct * __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active, struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6); @@ -591,14 +589,6 @@ static inline bool schedule_delayed_work(struct delayed_work *dwork, return queue_delayed_work(system_wq, dwork, delay); } -/** - * keventd_up - is workqueue initialized yet? - */ -static inline bool keventd_up(void) -{ - return wq_online; -} - #ifndef CONFIG_SMP static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg) { diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 15d0811c9e91..ad0cd439223b 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -290,7 +290,7 @@ module_param_named(disable_numa, wq_disable_numa, bool, 0444); static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); module_param_named(power_efficient, wq_power_efficient, bool, 0444); -bool wq_online; /* can kworkers be created yet? */ +static bool wq_online; /* can kworkers be created yet? */ static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ -- cgit v1.2.3-71-gd317 From 42412c3aae5d8ea57a46b8ff86bb67bc1a270d9c Mon Sep 17 00:00:00 2001 From: Silvio Fricke Date: Fri, 28 Oct 2016 10:14:09 +0200 Subject: workqueue: kerneldocify workqueue_attrs Only formating changes. Signed-off-by: Silvio Fricke Acked-by: Tejun Heo Signed-off-by: Jonathan Corbet --- include/linux/workqueue.h | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-) (limited to 'include/linux/workqueue.h') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index fc6e22186405..d4f16cf6281c 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -119,18 +119,30 @@ struct delayed_work { int cpu; }; -/* - * A struct for workqueue attributes. This can be used to change - * attributes of an unbound workqueue. +/** + * struct workqueue_attrs - A struct for workqueue attributes. * - * Unlike other fields, ->no_numa isn't a property of a worker_pool. It - * only modifies how apply_workqueue_attrs() select pools and thus doesn't - * participate in pool hash calculations or equality comparisons. + * This can be used to change attributes of an unbound workqueue. */ struct workqueue_attrs { - int nice; /* nice level */ - cpumask_var_t cpumask; /* allowed CPUs */ - bool no_numa; /* disable NUMA affinity */ + /** + * @nice: nice level + */ + int nice; + + /** + * @cpumask: allowed CPUs + */ + cpumask_var_t cpumask; + + /** + * @no_numa: disable NUMA affinity + * + * Unlike other fields, ``no_numa`` isn't a property of a worker_pool. It + * only modifies how :c:func:`apply_workqueue_attrs` select pools and thus + * doesn't participate in pool hash calculations or equality comparisons. + */ + bool no_numa; }; static inline struct delayed_work *to_delayed_work(struct work_struct *work) @@ -272,7 +284,7 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; } /* * Workqueue flags and constants. For details, please refer to - * Documentation/workqueue.txt. + * Documentation/core-api/workqueue.rst. */ enum { WQ_UNBOUND = 1 << 1, /* not bound to any cpu */ @@ -370,7 +382,8 @@ __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active, * @args...: args for @fmt * * Allocate a workqueue with the specified parameters. For detailed - * information on WQ_* flags, please refer to Documentation/workqueue.txt. + * information on WQ_* flags, please refer to + * Documentation/core-api/workqueue.rst. * * The __lock_name macro dance is to guarantee that single lock_class_key * doesn't end up with different namesm, which isn't allowed by lockdep. -- cgit v1.2.3-71-gd317