OpenCloudOS-Kernel/include/linux/workqueue.h

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/*
* workqueue.h --- work queue handling for Linux.
*/
#ifndef _LINUX_WORKQUEUE_H
#define _LINUX_WORKQUEUE_H
#include <linux/timer.h>
#include <linux/linkage.h>
#include <linux/bitops.h>
#include <linux/lockdep.h>
#include <linux/threads.h>
#include <linux/atomic.h>
#include <linux/cpumask.h>
struct workqueue_struct;
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struct work_struct;
typedef void (*work_func_t)(struct work_struct *work);
void delayed_work_timer_fn(unsigned long __data);
/*
* The first word is the work queue pointer and the flags rolled into
* one
*/
#define work_data_bits(work) ((unsigned long *)(&(work)->data))
enum {
WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */
WORK_STRUCT_DELAYED_BIT = 1, /* work item is delayed */
WORK_STRUCT_PWQ_BIT = 2, /* data points to pwq */
WORK_STRUCT_LINKED_BIT = 3, /* next work is linked to this one */
#ifdef CONFIG_DEBUG_OBJECTS_WORK
WORK_STRUCT_STATIC_BIT = 4, /* static initializer (debugobjects) */
WORK_STRUCT_COLOR_SHIFT = 5, /* color for workqueue flushing */
#else
WORK_STRUCT_COLOR_SHIFT = 4, /* color for workqueue flushing */
#endif
workqueue: reimplement workqueue flushing using color coded works Reimplement workqueue flushing using color coded works. wq has the current work color which is painted on the works being issued via cwqs. Flushing a workqueue is achieved by advancing the current work colors of cwqs and waiting for all the works which have any of the previous colors to drain. Currently there are 16 possible colors, one is reserved for no color and 15 colors are useable allowing 14 concurrent flushes. When color space gets full, flush attempts are batched up and processed together when color frees up, so even with many concurrent flushers, the new implementation won't build up huge queue of flushers which has to be processed one after another. Only works which are queued via __queue_work() are colored. Works which are directly put on queue using insert_work() use NO_COLOR and don't participate in workqueue flushing. Currently only works used for work-specific flush fall in this category. This new implementation leaves only cleanup_workqueue_thread() as the user of flush_cpu_workqueue(). Just make its users use flush_workqueue() and kthread_stop() directly and kill cleanup_workqueue_thread(). As workqueue flushing doesn't use barrier request anymore, the comment describing the complex synchronization around it in cleanup_workqueue_thread() is removed together with the function. This new implementation is to allow having and sharing multiple workers per cpu. Please note that one more bit is reserved for a future work flag by this patch. This is to avoid shifting bits and updating comments later. Signed-off-by: Tejun Heo <tj@kernel.org>
2010-06-29 16:07:11 +08:00
WORK_STRUCT_COLOR_BITS = 4,
WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
WORK_STRUCT_DELAYED = 1 << WORK_STRUCT_DELAYED_BIT,
WORK_STRUCT_PWQ = 1 << WORK_STRUCT_PWQ_BIT,
WORK_STRUCT_LINKED = 1 << WORK_STRUCT_LINKED_BIT,
#ifdef CONFIG_DEBUG_OBJECTS_WORK
WORK_STRUCT_STATIC = 1 << WORK_STRUCT_STATIC_BIT,
#else
WORK_STRUCT_STATIC = 0,
#endif
workqueue: reimplement workqueue flushing using color coded works Reimplement workqueue flushing using color coded works. wq has the current work color which is painted on the works being issued via cwqs. Flushing a workqueue is achieved by advancing the current work colors of cwqs and waiting for all the works which have any of the previous colors to drain. Currently there are 16 possible colors, one is reserved for no color and 15 colors are useable allowing 14 concurrent flushes. When color space gets full, flush attempts are batched up and processed together when color frees up, so even with many concurrent flushers, the new implementation won't build up huge queue of flushers which has to be processed one after another. Only works which are queued via __queue_work() are colored. Works which are directly put on queue using insert_work() use NO_COLOR and don't participate in workqueue flushing. Currently only works used for work-specific flush fall in this category. This new implementation leaves only cleanup_workqueue_thread() as the user of flush_cpu_workqueue(). Just make its users use flush_workqueue() and kthread_stop() directly and kill cleanup_workqueue_thread(). As workqueue flushing doesn't use barrier request anymore, the comment describing the complex synchronization around it in cleanup_workqueue_thread() is removed together with the function. This new implementation is to allow having and sharing multiple workers per cpu. Please note that one more bit is reserved for a future work flag by this patch. This is to avoid shifting bits and updating comments later. Signed-off-by: Tejun Heo <tj@kernel.org>
2010-06-29 16:07:11 +08:00
/*
* The last color is no color used for works which don't
* participate in workqueue flushing.
*/
WORK_NR_COLORS = (1 << WORK_STRUCT_COLOR_BITS) - 1,
WORK_NO_COLOR = WORK_NR_COLORS,
/* special cpu IDs */
WORK_CPU_UNBOUND = NR_CPUS,
WORK_CPU_END = NR_CPUS + 1,
workqueue: reimplement workqueue flushing using color coded works Reimplement workqueue flushing using color coded works. wq has the current work color which is painted on the works being issued via cwqs. Flushing a workqueue is achieved by advancing the current work colors of cwqs and waiting for all the works which have any of the previous colors to drain. Currently there are 16 possible colors, one is reserved for no color and 15 colors are useable allowing 14 concurrent flushes. When color space gets full, flush attempts are batched up and processed together when color frees up, so even with many concurrent flushers, the new implementation won't build up huge queue of flushers which has to be processed one after another. Only works which are queued via __queue_work() are colored. Works which are directly put on queue using insert_work() use NO_COLOR and don't participate in workqueue flushing. Currently only works used for work-specific flush fall in this category. This new implementation leaves only cleanup_workqueue_thread() as the user of flush_cpu_workqueue(). Just make its users use flush_workqueue() and kthread_stop() directly and kill cleanup_workqueue_thread(). As workqueue flushing doesn't use barrier request anymore, the comment describing the complex synchronization around it in cleanup_workqueue_thread() is removed together with the function. This new implementation is to allow having and sharing multiple workers per cpu. Please note that one more bit is reserved for a future work flag by this patch. This is to avoid shifting bits and updating comments later. Signed-off-by: Tejun Heo <tj@kernel.org>
2010-06-29 16:07:11 +08:00
/*
* Reserve 7 bits off of pwq pointer w/ debugobjects turned off.
* This makes pwqs aligned to 256 bytes and allows 15 workqueue
* flush colors.
workqueue: reimplement workqueue flushing using color coded works Reimplement workqueue flushing using color coded works. wq has the current work color which is painted on the works being issued via cwqs. Flushing a workqueue is achieved by advancing the current work colors of cwqs and waiting for all the works which have any of the previous colors to drain. Currently there are 16 possible colors, one is reserved for no color and 15 colors are useable allowing 14 concurrent flushes. When color space gets full, flush attempts are batched up and processed together when color frees up, so even with many concurrent flushers, the new implementation won't build up huge queue of flushers which has to be processed one after another. Only works which are queued via __queue_work() are colored. Works which are directly put on queue using insert_work() use NO_COLOR and don't participate in workqueue flushing. Currently only works used for work-specific flush fall in this category. This new implementation leaves only cleanup_workqueue_thread() as the user of flush_cpu_workqueue(). Just make its users use flush_workqueue() and kthread_stop() directly and kill cleanup_workqueue_thread(). As workqueue flushing doesn't use barrier request anymore, the comment describing the complex synchronization around it in cleanup_workqueue_thread() is removed together with the function. This new implementation is to allow having and sharing multiple workers per cpu. Please note that one more bit is reserved for a future work flag by this patch. This is to avoid shifting bits and updating comments later. Signed-off-by: Tejun Heo <tj@kernel.org>
2010-06-29 16:07:11 +08:00
*/
WORK_STRUCT_FLAG_BITS = WORK_STRUCT_COLOR_SHIFT +
WORK_STRUCT_COLOR_BITS,
/* data contains off-queue information when !WORK_STRUCT_PWQ */
WORK_OFFQ_FLAG_BASE = WORK_STRUCT_COLOR_SHIFT,
workqueue: mark a work item being canceled as such There can be two reasons try_to_grab_pending() can fail with -EAGAIN. One is when someone else is queueing or deqeueing the work item. With the previous patches, it is guaranteed that PENDING and queued state will soon agree making it safe to busy-retry in this case. The other is if multiple __cancel_work_timer() invocations are racing one another. __cancel_work_timer() grabs PENDING and then waits for running instances of the target work item on all CPUs while holding PENDING and !queued. try_to_grab_pending() invoked from another task will keep returning -EAGAIN while the current owner is waiting. Not distinguishing the two cases is okay because __cancel_work_timer() is the only user of try_to_grab_pending() and it invokes wait_on_work() whenever grabbing fails. For the first case, busy looping should be fine but wait_on_work() doesn't cause any critical problem. For the latter case, the new contender usually waits for the same condition as the current owner, so no unnecessarily extended busy-looping happens. Combined, these make __cancel_work_timer() technically correct even without irq protection while grabbing PENDING or distinguishing the two different cases. While the current code is technically correct, not distinguishing the two cases makes it difficult to use try_to_grab_pending() for other purposes than canceling because it's impossible to tell whether it's safe to busy-retry grabbing. This patch adds a mechanism to mark a work item being canceled. try_to_grab_pending() now disables irq on success and returns -EAGAIN to indicate that grabbing failed but PENDING and queued states are gonna agree soon and it's safe to busy-loop. It returns -ENOENT if the work item is being canceled and it may stay PENDING && !queued for arbitrary amount of time. __cancel_work_timer() is modified to mark the work canceling with WORK_OFFQ_CANCELING after grabbing PENDING, thus making try_to_grab_pending() fail with -ENOENT instead of -EAGAIN. Also, it invokes wait_on_work() iff grabbing failed with -ENOENT. This isn't necessary for correctness but makes it consistent with other future users of try_to_grab_pending(). v2: try_to_grab_pending() was testing preempt_count() to ensure that the caller has disabled preemption. This triggers spuriously if !CONFIG_PREEMPT_COUNT. Use preemptible() instead. Reported by Fengguang Wu. v3: Updated so that try_to_grab_pending() disables irq on success rather than requiring preemption disabled by the caller. This makes busy-looping easier and will allow try_to_grap_pending() to be used from bh/irq contexts. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Fengguang Wu <fengguang.wu@intel.com>
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WORK_OFFQ_CANCELING = (1 << WORK_OFFQ_FLAG_BASE),
/*
* When a work item is off queue, its high bits point to the last
* pool it was on. Cap at 31 bits and use the highest number to
* indicate that no pool is associated.
*/
workqueue: mark a work item being canceled as such There can be two reasons try_to_grab_pending() can fail with -EAGAIN. One is when someone else is queueing or deqeueing the work item. With the previous patches, it is guaranteed that PENDING and queued state will soon agree making it safe to busy-retry in this case. The other is if multiple __cancel_work_timer() invocations are racing one another. __cancel_work_timer() grabs PENDING and then waits for running instances of the target work item on all CPUs while holding PENDING and !queued. try_to_grab_pending() invoked from another task will keep returning -EAGAIN while the current owner is waiting. Not distinguishing the two cases is okay because __cancel_work_timer() is the only user of try_to_grab_pending() and it invokes wait_on_work() whenever grabbing fails. For the first case, busy looping should be fine but wait_on_work() doesn't cause any critical problem. For the latter case, the new contender usually waits for the same condition as the current owner, so no unnecessarily extended busy-looping happens. Combined, these make __cancel_work_timer() technically correct even without irq protection while grabbing PENDING or distinguishing the two different cases. While the current code is technically correct, not distinguishing the two cases makes it difficult to use try_to_grab_pending() for other purposes than canceling because it's impossible to tell whether it's safe to busy-retry grabbing. This patch adds a mechanism to mark a work item being canceled. try_to_grab_pending() now disables irq on success and returns -EAGAIN to indicate that grabbing failed but PENDING and queued states are gonna agree soon and it's safe to busy-loop. It returns -ENOENT if the work item is being canceled and it may stay PENDING && !queued for arbitrary amount of time. __cancel_work_timer() is modified to mark the work canceling with WORK_OFFQ_CANCELING after grabbing PENDING, thus making try_to_grab_pending() fail with -ENOENT instead of -EAGAIN. Also, it invokes wait_on_work() iff grabbing failed with -ENOENT. This isn't necessary for correctness but makes it consistent with other future users of try_to_grab_pending(). v2: try_to_grab_pending() was testing preempt_count() to ensure that the caller has disabled preemption. This triggers spuriously if !CONFIG_PREEMPT_COUNT. Use preemptible() instead. Reported by Fengguang Wu. v3: Updated so that try_to_grab_pending() disables irq on success rather than requiring preemption disabled by the caller. This makes busy-looping easier and will allow try_to_grap_pending() to be used from bh/irq contexts. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Fengguang Wu <fengguang.wu@intel.com>
2012-08-04 01:30:46 +08:00
WORK_OFFQ_FLAG_BITS = 1,
WORK_OFFQ_POOL_SHIFT = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
WORK_OFFQ_LEFT = BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
WORK_OFFQ_POOL_BITS = WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
WORK_OFFQ_POOL_NONE = (1LU << WORK_OFFQ_POOL_BITS) - 1,
/* convenience constants */
WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
WORK_STRUCT_NO_POOL = (unsigned long)WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT,
/* bit mask for work_busy() return values */
WORK_BUSY_PENDING = 1 << 0,
WORK_BUSY_RUNNING = 1 << 1,
workqueue: include workqueue info when printing debug dump of a worker task 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: [<ffffffff81c61845>] dump_stack+0x19/0x1b [<ffffffff8108f50f>] warn_slowpath_common+0x7f/0xc0 [<ffffffff8108f56a>] warn_slowpath_null+0x1a/0x20 [<ffffffff81200150>] bdi_writeback_workfn+0x2a0/0x3b0 ... Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Acked-by: Jan Kara <jack@suse.cz> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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/* maximum string length for set_worker_desc() */
WORKER_DESC_LEN = 24,
};
struct work_struct {
atomic_long_t data;
struct list_head entry;
work_func_t func;
#ifdef CONFIG_LOCKDEP
struct lockdep_map lockdep_map;
#endif
};
#define WORK_DATA_INIT() ATOMIC_LONG_INIT(WORK_STRUCT_NO_POOL)
#define WORK_DATA_STATIC_INIT() \
ATOMIC_LONG_INIT(WORK_STRUCT_NO_POOL | WORK_STRUCT_STATIC)
struct delayed_work {
struct work_struct work;
struct timer_list timer;
workqueue: add delayed_work->wq to simplify reentrancy handling To avoid executing the same work item from multiple CPUs concurrently, a work_struct records the last pool it was on in its ->data so that, on the next queueing, the pool can be queried to determine whether the work item is still executing or not. A delayed_work goes through timer before actually being queued on the target workqueue and the timer needs to know the target workqueue and CPU. This is currently achieved by modifying delayed_work->work.data such that it points to the cwq which points to the target workqueue and the last CPU the work item was on. __queue_delayed_work() extracts the last CPU from delayed_work->work.data and then combines it with the target workqueue to create new work.data. The only thing this rather ugly hack achieves is encoding the target workqueue into delayed_work->work.data without using a separate field, which could be a trade off one can make; unfortunately, this entangles work->data management between regular workqueue and delayed_work code by setting cwq pointer before the work item is actually queued and becomes a hindrance for further improvements of work->data handling. This can be easily made sane by adding a target workqueue field to delayed_work. While delayed_work is used widely in the kernel and this does make it a bit larger (<5%), I think this is the right trade-off especially given the prospect of much saner handling of work->data which currently involves quite tricky memory barrier dancing, and don't expect to see any measureable effect. Add delayed_work->wq and drop the delayed_work->work.data overloading. tj: Rewrote the description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
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/* target workqueue and CPU ->timer uses to queue ->work */
struct workqueue_struct *wq;
int cpu;
};
/*
* A struct for workqueue attributes. This can be used to change
* attributes of an unbound workqueue.
*
* 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.
*/
struct workqueue_attrs {
int nice; /* nice level */
cpumask_var_t cpumask; /* allowed CPUs */
bool no_numa; /* disable NUMA affinity */
};
static inline struct delayed_work *to_delayed_work(struct work_struct *work)
{
return container_of(work, struct delayed_work, work);
}
struct execute_work {
struct work_struct work;
};
#ifdef CONFIG_LOCKDEP
/*
* NB: because we have to copy the lockdep_map, setting _key
* here is required, otherwise it could get initialised to the
* copy of the lockdep_map!
*/
#define __WORK_INIT_LOCKDEP_MAP(n, k) \
.lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
#else
#define __WORK_INIT_LOCKDEP_MAP(n, k)
#endif
#define __WORK_INITIALIZER(n, f) { \
.data = WORK_DATA_STATIC_INIT(), \
.entry = { &(n).entry, &(n).entry }, \
.func = (f), \
__WORK_INIT_LOCKDEP_MAP(#n, &(n)) \
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}
#define __DELAYED_WORK_INITIALIZER(n, f, tflags) { \
.work = __WORK_INITIALIZER((n).work, (f)), \
.timer = __TIMER_INITIALIZER(delayed_work_timer_fn, \
0, (unsigned long)&(n), \
(tflags) | TIMER_IRQSAFE), \
}
#define DECLARE_WORK(n, f) \
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struct work_struct n = __WORK_INITIALIZER(n, f)
#define DECLARE_DELAYED_WORK(n, f) \
struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
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#define DECLARE_DEFERRABLE_WORK(n, f) \
struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
/*
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* initialize a work item's function pointer
*/
#define PREPARE_WORK(_work, _func) \
do { \
(_work)->func = (_func); \
} while (0)
#define PREPARE_DELAYED_WORK(_work, _func) \
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PREPARE_WORK(&(_work)->work, (_func))
#ifdef CONFIG_DEBUG_OBJECTS_WORK
extern void __init_work(struct work_struct *work, int onstack);
extern void destroy_work_on_stack(struct work_struct *work);
static inline unsigned int work_static(struct work_struct *work)
{
return *work_data_bits(work) & WORK_STRUCT_STATIC;
}
#else
static inline void __init_work(struct work_struct *work, int onstack) { }
static inline void destroy_work_on_stack(struct work_struct *work) { }
static inline unsigned int work_static(struct work_struct *work) { return 0; }
#endif
/*
* initialize all of a work item in one go
*
* NOTE! No point in using "atomic_long_set()": using a direct
* assignment of the work data initializer allows the compiler
* to generate better code.
*/
#ifdef CONFIG_LOCKDEP
#define __INIT_WORK(_work, _func, _onstack) \
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do { \
static struct lock_class_key __key; \
\
__init_work((_work), _onstack); \
(_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0); \
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INIT_LIST_HEAD(&(_work)->entry); \
PREPARE_WORK((_work), (_func)); \
} while (0)
#else
#define __INIT_WORK(_work, _func, _onstack) \
do { \
__init_work((_work), _onstack); \
(_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
INIT_LIST_HEAD(&(_work)->entry); \
PREPARE_WORK((_work), (_func)); \
} while (0)
#endif
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#define INIT_WORK(_work, _func) \
do { \
__INIT_WORK((_work), (_func), 0); \
} while (0)
#define INIT_WORK_ONSTACK(_work, _func) \
do { \
__INIT_WORK((_work), (_func), 1); \
} while (0)
#define __INIT_DELAYED_WORK(_work, _func, _tflags) \
do { \
INIT_WORK(&(_work)->work, (_func)); \
__setup_timer(&(_work)->timer, delayed_work_timer_fn, \
(unsigned long)(_work), \
(_tflags) | TIMER_IRQSAFE); \
} while (0)
#define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags) \
do { \
INIT_WORK_ONSTACK(&(_work)->work, (_func)); \
__setup_timer_on_stack(&(_work)->timer, \
delayed_work_timer_fn, \
(unsigned long)(_work), \
(_tflags) | TIMER_IRQSAFE); \
} while (0)
#define INIT_DELAYED_WORK(_work, _func) \
__INIT_DELAYED_WORK(_work, _func, 0)
#define INIT_DELAYED_WORK_ONSTACK(_work, _func) \
__INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
#define INIT_DEFERRABLE_WORK(_work, _func) \
__INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
#define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func) \
__INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
/**
* work_pending - Find out whether a work item is currently pending
* @work: The work item in question
*/
#define work_pending(work) \
test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
/**
* delayed_work_pending - Find out whether a delayable work item is currently
* pending
* @work: The work item in question
*/
#define delayed_work_pending(w) \
work_pending(&(w)->work)
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/**
* work_clear_pending - for internal use only, mark a work item as not pending
* @work: The work item in question
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*/
#define work_clear_pending(work) \
clear_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
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/*
* Workqueue flags and constants. For details, please refer to
* Documentation/workqueue.txt.
*/
enum {
/*
* All wqs are now non-reentrant making the following flag
* meaningless. Will be removed.
*/
WQ_NON_REENTRANT = 1 << 0, /* DEPRECATED */
WQ_UNBOUND = 1 << 1, /* not bound to any cpu */
WQ_FREEZABLE = 1 << 2, /* freeze during suspend */
WQ_MEM_RECLAIM = 1 << 3, /* may be used for memory reclaim */
WQ_HIGHPRI = 1 << 4, /* high priority */
WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */
WQ_SYSFS = 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
/*
* Per-cpu workqueues are generally preferred because they tend to
* show better performance thanks to cache locality. Per-cpu
* workqueues exclude the scheduler from choosing the CPU to
* execute the worker threads, which has an unfortunate side effect
* of increasing power consumption.
*
* The scheduler considers a CPU idle if it doesn't have any task
* to execute and tries to keep idle cores idle to conserve power;
* however, for example, a per-cpu work item scheduled from an
* interrupt handler on an idle CPU will force the scheduler to
* excute the work item on that CPU breaking the idleness, which in
* turn may lead to more scheduling choices which are sub-optimal
* in terms of power consumption.
*
* Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
* but become unbound if workqueue.power_efficient kernel param is
* specified. Per-cpu workqueues which are identified to
* contribute significantly to power-consumption are identified and
* marked with this flag and enabling the power_efficient mode
* leads to noticeable power saving at the cost of small
* performance disadvantage.
*
* http://thread.gmane.org/gmane.linux.kernel/1480396
*/
WQ_POWER_EFFICIENT = 1 << 7,
__WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */
__WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */
WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */
WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
WQ_DFL_ACTIVE = WQ_MAX_ACTIVE / 2,
};
/* unbound wq's aren't per-cpu, scale max_active according to #cpus */
#define WQ_UNBOUND_MAX_ACTIVE \
max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
2006-11-22 22:55:48 +08:00
/*
* System-wide workqueues which are always present.
*
* system_wq is the one used by schedule[_delayed]_work[_on]().
* Multi-CPU multi-threaded. There are users which expect relatively
* short queue flush time. Don't queue works which can run for too
* long.
*
* system_long_wq is similar to system_wq but may host long running
* works. Queue flushing might take relatively long.
*
* system_unbound_wq is unbound workqueue. Workers are not bound to
* any specific CPU, not concurrency managed, and all queued works are
* executed immediately as long as max_active limit is not reached and
* resources are available.
*
* system_freezable_wq is equivalent to system_wq except that it's
* freezable.
*
* *_power_efficient_wq are inclined towards saving power and converted
* into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
* they are same as their non-power-efficient counterparts - e.g.
* system_power_efficient_wq is identical to system_wq if
* 'wq_power_efficient' is disabled. See WQ_POWER_EFFICIENT for more info.
*/
extern struct workqueue_struct *system_wq;
extern struct workqueue_struct *system_long_wq;
extern struct workqueue_struct *system_unbound_wq;
extern struct workqueue_struct *system_freezable_wq;
extern struct workqueue_struct *system_power_efficient_wq;
extern struct workqueue_struct *system_freezable_power_efficient_wq;
static inline struct workqueue_struct * __deprecated __system_nrt_wq(void)
{
return system_wq;
}
static inline struct workqueue_struct * __deprecated __system_nrt_freezable_wq(void)
{
return system_freezable_wq;
}
/* equivlalent to system_wq and system_freezable_wq, deprecated */
#define system_nrt_wq __system_nrt_wq()
#define system_nrt_freezable_wq __system_nrt_freezable_wq()
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);
/**
* alloc_workqueue - allocate a workqueue
* @fmt: printf format for the name of the workqueue
* @flags: WQ_* flags
* @max_active: max in-flight work items, 0 for default
* @args: args for @fmt
*
* Allocate a workqueue with the specified parameters. For detailed
* information on WQ_* flags, please refer to Documentation/workqueue.txt.
*
* 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.
*
* RETURNS:
* Pointer to the allocated workqueue on success, %NULL on failure.
*/
#ifdef CONFIG_LOCKDEP
#define alloc_workqueue(fmt, flags, max_active, args...) \
({ \
static struct lock_class_key __key; \
const char *__lock_name; \
\
if (__builtin_constant_p(fmt)) \
__lock_name = (fmt); \
else \
__lock_name = #fmt; \
\
__alloc_workqueue_key((fmt), (flags), (max_active), \
&__key, __lock_name, ##args); \
})
#else
#define alloc_workqueue(fmt, flags, max_active, args...) \
__alloc_workqueue_key((fmt), (flags), (max_active), \
NULL, NULL, ##args)
#endif
/**
* alloc_ordered_workqueue - allocate an ordered workqueue
* @fmt: printf format for the name of the workqueue
* @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
* @args: args for @fmt
*
* Allocate an ordered workqueue. An ordered workqueue executes at
* most one work item at any given time in the queued order. They are
* implemented as unbound workqueues with @max_active of one.
*
* RETURNS:
* Pointer to the allocated workqueue on success, %NULL on failure.
*/
#define alloc_ordered_workqueue(fmt, flags, args...) \
alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args)
#define create_workqueue(name) \
alloc_workqueue("%s", WQ_MEM_RECLAIM, 1, (name))
#define create_freezable_workqueue(name) \
alloc_workqueue("%s", WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, \
1, (name))
#define create_singlethread_workqueue(name) \
alloc_workqueue("%s", WQ_UNBOUND | WQ_MEM_RECLAIM, 1, (name))
extern void destroy_workqueue(struct workqueue_struct *wq);
struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
void free_workqueue_attrs(struct workqueue_attrs *attrs);
int apply_workqueue_attrs(struct workqueue_struct *wq,
const struct workqueue_attrs *attrs);
extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
struct work_struct *work);
extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
struct delayed_work *work, unsigned long delay);
extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
struct delayed_work *dwork, unsigned long delay);
extern void flush_workqueue(struct workqueue_struct *wq);
extern void drain_workqueue(struct workqueue_struct *wq);
extern void flush_scheduled_work(void);
2006-11-22 22:55:48 +08:00
extern int schedule_on_each_cpu(work_func_t func);
2006-11-22 22:55:48 +08:00
int execute_in_process_context(work_func_t fn, struct execute_work *);
extern bool flush_work(struct work_struct *work);
extern bool cancel_work_sync(struct work_struct *work);
extern bool flush_delayed_work(struct delayed_work *dwork);
extern bool cancel_delayed_work(struct delayed_work *dwork);
extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
extern void workqueue_set_max_active(struct workqueue_struct *wq,
int max_active);
extern bool current_is_workqueue_rescuer(void);
extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
extern unsigned int work_busy(struct work_struct *work);
workqueue: include workqueue info when printing debug dump of a worker task 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: [<ffffffff81c61845>] dump_stack+0x19/0x1b [<ffffffff8108f50f>] warn_slowpath_common+0x7f/0xc0 [<ffffffff8108f56a>] warn_slowpath_null+0x1a/0x20 [<ffffffff81200150>] bdi_writeback_workfn+0x2a0/0x3b0 ... Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Acked-by: Jan Kara <jack@suse.cz> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 06:27:22 +08:00
extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
extern void print_worker_info(const char *log_lvl, struct task_struct *task);
/**
* queue_work - queue work on a workqueue
* @wq: workqueue to use
* @work: work to queue
*
* Returns %false if @work was already on a queue, %true otherwise.
*
* We queue the work to the CPU on which it was submitted, but if the CPU dies
* it can be processed by another CPU.
*/
static inline bool queue_work(struct workqueue_struct *wq,
struct work_struct *work)
{
return queue_work_on(WORK_CPU_UNBOUND, wq, work);
}
/**
* queue_delayed_work - queue work on a workqueue after delay
* @wq: workqueue to use
* @dwork: delayable work to queue
* @delay: number of jiffies to wait before queueing
*
* Equivalent to queue_delayed_work_on() but tries to use the local CPU.
*/
static inline bool queue_delayed_work(struct workqueue_struct *wq,
struct delayed_work *dwork,
unsigned long delay)
{
return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
}
/**
* mod_delayed_work - modify delay of or queue a delayed work
* @wq: workqueue to use
* @dwork: work to queue
* @delay: number of jiffies to wait before queueing
*
* mod_delayed_work_on() on local CPU.
*/
static inline bool mod_delayed_work(struct workqueue_struct *wq,
struct delayed_work *dwork,
unsigned long delay)
{
return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
}
/**
* schedule_work_on - put work task on a specific cpu
* @cpu: cpu to put the work task on
* @work: job to be done
*
* This puts a job on a specific cpu
*/
static inline bool schedule_work_on(int cpu, struct work_struct *work)
{
return queue_work_on(cpu, system_wq, work);
}
/**
* schedule_work - put work task in global workqueue
* @work: job to be done
*
* Returns %false if @work was already on the kernel-global workqueue and
* %true otherwise.
*
* This puts a job in the kernel-global workqueue if it was not already
* queued and leaves it in the same position on the kernel-global
* workqueue otherwise.
*/
static inline bool schedule_work(struct work_struct *work)
{
return queue_work(system_wq, work);
}
/**
* schedule_delayed_work_on - queue work in global workqueue on CPU after delay
* @cpu: cpu to use
* @dwork: job to be done
* @delay: number of jiffies to wait
*
* After waiting for a given time this puts a job in the kernel-global
* workqueue on the specified CPU.
*/
static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
unsigned long delay)
{
return queue_delayed_work_on(cpu, system_wq, dwork, delay);
}
/**
* schedule_delayed_work - put work task in global workqueue after delay
* @dwork: job to be done
* @delay: number of jiffies to wait or 0 for immediate execution
*
* After waiting for a given time this puts a job in the kernel-global
* workqueue.
*/
static inline bool schedule_delayed_work(struct delayed_work *dwork,
unsigned long delay)
{
return queue_delayed_work(system_wq, dwork, delay);
}
/**
* keventd_up - is workqueue initialized yet?
*/
static inline bool keventd_up(void)
{
return system_wq != NULL;
}
/*
* Like above, but uses del_timer() instead of del_timer_sync(). This means,
* if it returns 0 the timer function may be running and the queueing is in
* progress.
*/
static inline bool __deprecated __cancel_delayed_work(struct delayed_work *work)
{
bool ret;
ret = del_timer(&work->timer);
if (ret)
work_clear_pending(&work->work);
return ret;
}
/* used to be different but now identical to flush_work(), deprecated */
workqueue: deprecate flush[_delayed]_work_sync() flush[_delayed]_work_sync() are now spurious. Mark them deprecated and convert all users to flush[_delayed]_work(). If you're cc'd and wondering what's going on: Now all workqueues are non-reentrant and the regular flushes guarantee that the work item is not pending or running on any CPU on return, so there's no reason to use the sync flushes at all and they're going away. This patch doesn't make any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Russell King <linux@arm.linux.org.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Ian Campbell <ian.campbell@citrix.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mattia Dongili <malattia@linux.it> Cc: Kent Yoder <key@linux.vnet.ibm.com> Cc: David Airlie <airlied@linux.ie> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Karsten Keil <isdn@linux-pingi.de> Cc: Bryan Wu <bryan.wu@canonical.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Alasdair Kergon <agk@redhat.com> Cc: Mauro Carvalho Chehab <mchehab@infradead.org> Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de> Cc: David Woodhouse <dwmw2@infradead.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: linux-wireless@vger.kernel.org Cc: Anton Vorontsov <cbou@mail.ru> Cc: Sangbeom Kim <sbkim73@samsung.com> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Eric Van Hensbergen <ericvh@gmail.com> Cc: Takashi Iwai <tiwai@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Petr Vandrovec <petr@vandrovec.name> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Avi Kivity <avi@redhat.com>
2012-08-21 05:51:24 +08:00
static inline bool __deprecated flush_work_sync(struct work_struct *work)
{
return flush_work(work);
}
/* used to be different but now identical to flush_delayed_work(), deprecated */
workqueue: deprecate flush[_delayed]_work_sync() flush[_delayed]_work_sync() are now spurious. Mark them deprecated and convert all users to flush[_delayed]_work(). If you're cc'd and wondering what's going on: Now all workqueues are non-reentrant and the regular flushes guarantee that the work item is not pending or running on any CPU on return, so there's no reason to use the sync flushes at all and they're going away. This patch doesn't make any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Russell King <linux@arm.linux.org.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Ian Campbell <ian.campbell@citrix.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mattia Dongili <malattia@linux.it> Cc: Kent Yoder <key@linux.vnet.ibm.com> Cc: David Airlie <airlied@linux.ie> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Karsten Keil <isdn@linux-pingi.de> Cc: Bryan Wu <bryan.wu@canonical.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Alasdair Kergon <agk@redhat.com> Cc: Mauro Carvalho Chehab <mchehab@infradead.org> Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de> Cc: David Woodhouse <dwmw2@infradead.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: linux-wireless@vger.kernel.org Cc: Anton Vorontsov <cbou@mail.ru> Cc: Sangbeom Kim <sbkim73@samsung.com> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Eric Van Hensbergen <ericvh@gmail.com> Cc: Takashi Iwai <tiwai@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Petr Vandrovec <petr@vandrovec.name> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Avi Kivity <avi@redhat.com>
2012-08-21 05:51:24 +08:00
static inline bool __deprecated flush_delayed_work_sync(struct delayed_work *dwork)
{
return flush_delayed_work(dwork);
}
#ifndef CONFIG_SMP
static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
{
return fn(arg);
}
#else
long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
#endif /* CONFIG_SMP */
#ifdef CONFIG_FREEZER
extern void freeze_workqueues_begin(void);
extern bool freeze_workqueues_busy(void);
extern void thaw_workqueues(void);
#endif /* CONFIG_FREEZER */
#ifdef CONFIG_SYSFS
int workqueue_sysfs_register(struct workqueue_struct *wq);
#else /* CONFIG_SYSFS */
static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
{ return 0; }
#endif /* CONFIG_SYSFS */
#endif