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![Alan Stern](/assets/img/avatar_default.png)
This patch (as1519) fixes a bug in the block layer's disk-events polling. The polling is done by a work routine queued on the system_nrt_wq workqueue. Since that workqueue isn't freezable, the polling continues even in the middle of a system sleep transition. Obviously, polling a suspended drive for media changes and such isn't a good thing to do; in the case of USB mass-storage devices it can lead to real problems requiring device resets and even re-enumeration. The patch fixes things by creating a new system-wide, non-reentrant, freezable workqueue and using it for disk-events polling. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: <stable@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Jens Axboe <axboe@kernel.dk>
450 lines
14 KiB
C
450 lines
14 KiB
C
/*
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* workqueue.h --- work queue handling for Linux.
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*/
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#ifndef _LINUX_WORKQUEUE_H
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#define _LINUX_WORKQUEUE_H
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#include <linux/timer.h>
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#include <linux/linkage.h>
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#include <linux/bitops.h>
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#include <linux/lockdep.h>
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#include <linux/threads.h>
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#include <linux/atomic.h>
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struct workqueue_struct;
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struct work_struct;
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typedef void (*work_func_t)(struct work_struct *work);
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/*
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* The first word is the work queue pointer and the flags rolled into
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* one
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*/
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#define work_data_bits(work) ((unsigned long *)(&(work)->data))
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enum {
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WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */
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WORK_STRUCT_DELAYED_BIT = 1, /* work item is delayed */
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WORK_STRUCT_CWQ_BIT = 2, /* data points to cwq */
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WORK_STRUCT_LINKED_BIT = 3, /* next work is linked to this one */
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#ifdef CONFIG_DEBUG_OBJECTS_WORK
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WORK_STRUCT_STATIC_BIT = 4, /* static initializer (debugobjects) */
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WORK_STRUCT_COLOR_SHIFT = 5, /* color for workqueue flushing */
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#else
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WORK_STRUCT_COLOR_SHIFT = 4, /* color for workqueue flushing */
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#endif
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WORK_STRUCT_COLOR_BITS = 4,
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WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
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WORK_STRUCT_DELAYED = 1 << WORK_STRUCT_DELAYED_BIT,
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WORK_STRUCT_CWQ = 1 << WORK_STRUCT_CWQ_BIT,
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WORK_STRUCT_LINKED = 1 << WORK_STRUCT_LINKED_BIT,
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#ifdef CONFIG_DEBUG_OBJECTS_WORK
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WORK_STRUCT_STATIC = 1 << WORK_STRUCT_STATIC_BIT,
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#else
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WORK_STRUCT_STATIC = 0,
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#endif
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/*
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* The last color is no color used for works which don't
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* participate in workqueue flushing.
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*/
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WORK_NR_COLORS = (1 << WORK_STRUCT_COLOR_BITS) - 1,
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WORK_NO_COLOR = WORK_NR_COLORS,
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/* special cpu IDs */
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WORK_CPU_UNBOUND = NR_CPUS,
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WORK_CPU_NONE = NR_CPUS + 1,
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WORK_CPU_LAST = WORK_CPU_NONE,
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/*
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* Reserve 7 bits off of cwq pointer w/ debugobjects turned
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* off. This makes cwqs aligned to 256 bytes and allows 15
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* workqueue flush colors.
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*/
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WORK_STRUCT_FLAG_BITS = WORK_STRUCT_COLOR_SHIFT +
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WORK_STRUCT_COLOR_BITS,
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WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
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WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
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WORK_STRUCT_NO_CPU = WORK_CPU_NONE << WORK_STRUCT_FLAG_BITS,
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/* bit mask for work_busy() return values */
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WORK_BUSY_PENDING = 1 << 0,
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WORK_BUSY_RUNNING = 1 << 1,
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};
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struct work_struct {
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atomic_long_t data;
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struct list_head entry;
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work_func_t func;
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#ifdef CONFIG_LOCKDEP
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struct lockdep_map lockdep_map;
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#endif
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};
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#define WORK_DATA_INIT() ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU)
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#define WORK_DATA_STATIC_INIT() \
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ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU | WORK_STRUCT_STATIC)
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struct delayed_work {
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struct work_struct work;
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struct timer_list timer;
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};
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static inline struct delayed_work *to_delayed_work(struct work_struct *work)
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{
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return container_of(work, struct delayed_work, work);
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}
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struct execute_work {
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struct work_struct work;
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};
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#ifdef CONFIG_LOCKDEP
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/*
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* NB: because we have to copy the lockdep_map, setting _key
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* here is required, otherwise it could get initialised to the
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* copy of the lockdep_map!
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*/
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#define __WORK_INIT_LOCKDEP_MAP(n, k) \
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.lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
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#else
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#define __WORK_INIT_LOCKDEP_MAP(n, k)
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#endif
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#define __WORK_INITIALIZER(n, f) { \
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.data = WORK_DATA_STATIC_INIT(), \
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.entry = { &(n).entry, &(n).entry }, \
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.func = (f), \
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__WORK_INIT_LOCKDEP_MAP(#n, &(n)) \
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}
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#define __DELAYED_WORK_INITIALIZER(n, f) { \
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.work = __WORK_INITIALIZER((n).work, (f)), \
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.timer = TIMER_INITIALIZER(NULL, 0, 0), \
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}
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#define __DEFERRED_WORK_INITIALIZER(n, f) { \
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.work = __WORK_INITIALIZER((n).work, (f)), \
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.timer = TIMER_DEFERRED_INITIALIZER(NULL, 0, 0), \
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}
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#define DECLARE_WORK(n, f) \
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struct work_struct n = __WORK_INITIALIZER(n, f)
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#define DECLARE_DELAYED_WORK(n, f) \
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struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f)
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#define DECLARE_DEFERRED_WORK(n, f) \
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struct delayed_work n = __DEFERRED_WORK_INITIALIZER(n, f)
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/*
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* initialize a work item's function pointer
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*/
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#define PREPARE_WORK(_work, _func) \
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do { \
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(_work)->func = (_func); \
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} while (0)
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#define PREPARE_DELAYED_WORK(_work, _func) \
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PREPARE_WORK(&(_work)->work, (_func))
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#ifdef CONFIG_DEBUG_OBJECTS_WORK
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extern void __init_work(struct work_struct *work, int onstack);
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extern void destroy_work_on_stack(struct work_struct *work);
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static inline unsigned int work_static(struct work_struct *work)
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{
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return *work_data_bits(work) & WORK_STRUCT_STATIC;
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}
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#else
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static inline void __init_work(struct work_struct *work, int onstack) { }
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static inline void destroy_work_on_stack(struct work_struct *work) { }
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static inline unsigned int work_static(struct work_struct *work) { return 0; }
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#endif
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/*
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* initialize all of a work item in one go
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*
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* NOTE! No point in using "atomic_long_set()": using a direct
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* assignment of the work data initializer allows the compiler
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* to generate better code.
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*/
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#ifdef CONFIG_LOCKDEP
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#define __INIT_WORK(_work, _func, _onstack) \
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do { \
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static struct lock_class_key __key; \
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\
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__init_work((_work), _onstack); \
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(_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
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lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0);\
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INIT_LIST_HEAD(&(_work)->entry); \
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PREPARE_WORK((_work), (_func)); \
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} while (0)
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#else
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#define __INIT_WORK(_work, _func, _onstack) \
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do { \
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__init_work((_work), _onstack); \
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(_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
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INIT_LIST_HEAD(&(_work)->entry); \
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PREPARE_WORK((_work), (_func)); \
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} while (0)
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#endif
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#define INIT_WORK(_work, _func) \
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do { \
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__INIT_WORK((_work), (_func), 0); \
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} while (0)
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#define INIT_WORK_ONSTACK(_work, _func) \
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do { \
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__INIT_WORK((_work), (_func), 1); \
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} while (0)
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#define INIT_DELAYED_WORK(_work, _func) \
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do { \
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INIT_WORK(&(_work)->work, (_func)); \
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init_timer(&(_work)->timer); \
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} while (0)
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#define INIT_DELAYED_WORK_ONSTACK(_work, _func) \
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do { \
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INIT_WORK_ONSTACK(&(_work)->work, (_func)); \
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init_timer_on_stack(&(_work)->timer); \
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} while (0)
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#define INIT_DELAYED_WORK_DEFERRABLE(_work, _func) \
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do { \
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INIT_WORK(&(_work)->work, (_func)); \
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init_timer_deferrable(&(_work)->timer); \
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} while (0)
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/**
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* work_pending - Find out whether a work item is currently pending
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* @work: The work item in question
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*/
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#define work_pending(work) \
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test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
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/**
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* delayed_work_pending - Find out whether a delayable work item is currently
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* pending
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* @work: The work item in question
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*/
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#define delayed_work_pending(w) \
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work_pending(&(w)->work)
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/**
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* work_clear_pending - for internal use only, mark a work item as not pending
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* @work: The work item in question
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*/
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#define work_clear_pending(work) \
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clear_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
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/*
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* Workqueue flags and constants. For details, please refer to
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* Documentation/workqueue.txt.
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*/
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enum {
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WQ_NON_REENTRANT = 1 << 0, /* guarantee non-reentrance */
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WQ_UNBOUND = 1 << 1, /* not bound to any cpu */
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WQ_FREEZABLE = 1 << 2, /* freeze during suspend */
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WQ_MEM_RECLAIM = 1 << 3, /* may be used for memory reclaim */
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WQ_HIGHPRI = 1 << 4, /* high priority */
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WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */
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WQ_DRAINING = 1 << 6, /* internal: workqueue is draining */
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WQ_RESCUER = 1 << 7, /* internal: workqueue has rescuer */
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WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */
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WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
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WQ_DFL_ACTIVE = WQ_MAX_ACTIVE / 2,
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};
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/* unbound wq's aren't per-cpu, scale max_active according to #cpus */
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#define WQ_UNBOUND_MAX_ACTIVE \
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max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
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/*
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* System-wide workqueues which are always present.
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*
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* system_wq is the one used by schedule[_delayed]_work[_on]().
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* Multi-CPU multi-threaded. There are users which expect relatively
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* short queue flush time. Don't queue works which can run for too
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* long.
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*
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* system_long_wq is similar to system_wq but may host long running
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* works. Queue flushing might take relatively long.
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*
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* system_nrt_wq is non-reentrant and guarantees that any given work
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* item is never executed in parallel by multiple CPUs. Queue
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* flushing might take relatively long.
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*
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* system_unbound_wq is unbound workqueue. Workers are not bound to
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* any specific CPU, not concurrency managed, and all queued works are
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* executed immediately as long as max_active limit is not reached and
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* resources are available.
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*
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* system_freezable_wq is equivalent to system_wq except that it's
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* freezable.
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*
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* system_nrt_freezable_wq is equivalent to system_nrt_wq except that
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* it's freezable.
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*/
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extern struct workqueue_struct *system_wq;
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extern struct workqueue_struct *system_long_wq;
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extern struct workqueue_struct *system_nrt_wq;
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extern struct workqueue_struct *system_unbound_wq;
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extern struct workqueue_struct *system_freezable_wq;
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extern struct workqueue_struct *system_nrt_freezable_wq;
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extern struct workqueue_struct *
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__alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
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struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
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/**
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* alloc_workqueue - allocate a workqueue
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* @fmt: printf format for the name of the workqueue
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* @flags: WQ_* flags
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* @max_active: max in-flight work items, 0 for default
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* @args: args for @fmt
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*
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* Allocate a workqueue with the specified parameters. For detailed
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* information on WQ_* flags, please refer to Documentation/workqueue.txt.
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*
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* The __lock_name macro dance is to guarantee that single lock_class_key
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* doesn't end up with different namesm, which isn't allowed by lockdep.
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*
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* RETURNS:
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* Pointer to the allocated workqueue on success, %NULL on failure.
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*/
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#ifdef CONFIG_LOCKDEP
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#define alloc_workqueue(fmt, flags, max_active, args...) \
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({ \
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static struct lock_class_key __key; \
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const char *__lock_name; \
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\
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if (__builtin_constant_p(fmt)) \
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__lock_name = (fmt); \
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else \
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__lock_name = #fmt; \
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\
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__alloc_workqueue_key((fmt), (flags), (max_active), \
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&__key, __lock_name, ##args); \
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})
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#else
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#define alloc_workqueue(fmt, flags, max_active, args...) \
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__alloc_workqueue_key((fmt), (flags), (max_active), \
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NULL, NULL, ##args)
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#endif
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/**
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* alloc_ordered_workqueue - allocate an ordered workqueue
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* @fmt: printf format for the name of the workqueue
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* @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
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* @args: args for @fmt
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*
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* Allocate an ordered workqueue. An ordered workqueue executes at
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* most one work item at any given time in the queued order. They are
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* implemented as unbound workqueues with @max_active of one.
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*
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* RETURNS:
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* Pointer to the allocated workqueue on success, %NULL on failure.
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*/
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#define alloc_ordered_workqueue(fmt, flags, args...) \
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alloc_workqueue(fmt, WQ_UNBOUND | (flags), 1, ##args)
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#define create_workqueue(name) \
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alloc_workqueue((name), WQ_MEM_RECLAIM, 1)
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#define create_freezable_workqueue(name) \
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alloc_workqueue((name), WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
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#define create_singlethread_workqueue(name) \
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alloc_workqueue((name), WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
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extern void destroy_workqueue(struct workqueue_struct *wq);
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extern int queue_work(struct workqueue_struct *wq, struct work_struct *work);
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extern int queue_work_on(int cpu, struct workqueue_struct *wq,
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struct work_struct *work);
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extern int queue_delayed_work(struct workqueue_struct *wq,
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struct delayed_work *work, unsigned long delay);
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extern int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
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struct delayed_work *work, unsigned long delay);
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extern void flush_workqueue(struct workqueue_struct *wq);
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extern void drain_workqueue(struct workqueue_struct *wq);
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extern void flush_scheduled_work(void);
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extern int schedule_work(struct work_struct *work);
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extern int schedule_work_on(int cpu, struct work_struct *work);
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extern int schedule_delayed_work(struct delayed_work *work, unsigned long delay);
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extern int schedule_delayed_work_on(int cpu, struct delayed_work *work,
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unsigned long delay);
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extern int schedule_on_each_cpu(work_func_t func);
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extern int keventd_up(void);
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int execute_in_process_context(work_func_t fn, struct execute_work *);
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extern bool flush_work(struct work_struct *work);
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extern bool flush_work_sync(struct work_struct *work);
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extern bool cancel_work_sync(struct work_struct *work);
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extern bool flush_delayed_work(struct delayed_work *dwork);
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extern bool flush_delayed_work_sync(struct delayed_work *work);
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extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
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extern void workqueue_set_max_active(struct workqueue_struct *wq,
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int max_active);
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extern bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq);
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extern unsigned int work_cpu(struct work_struct *work);
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extern unsigned int work_busy(struct work_struct *work);
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/*
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* Kill off a pending schedule_delayed_work(). Note that the work callback
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* function may still be running on return from cancel_delayed_work(), unless
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* it returns 1 and the work doesn't re-arm itself. Run flush_workqueue() or
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* cancel_work_sync() to wait on it.
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*/
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static inline bool cancel_delayed_work(struct delayed_work *work)
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{
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bool ret;
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ret = del_timer_sync(&work->timer);
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if (ret)
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work_clear_pending(&work->work);
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return ret;
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}
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/*
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* Like above, but uses del_timer() instead of del_timer_sync(). This means,
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* if it returns 0 the timer function may be running and the queueing is in
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* progress.
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*/
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static inline bool __cancel_delayed_work(struct delayed_work *work)
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{
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bool ret;
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ret = del_timer(&work->timer);
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if (ret)
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work_clear_pending(&work->work);
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return ret;
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}
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#ifndef CONFIG_SMP
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static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
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{
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return fn(arg);
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}
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#else
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long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg);
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#endif /* CONFIG_SMP */
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#ifdef CONFIG_FREEZER
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extern void freeze_workqueues_begin(void);
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extern bool freeze_workqueues_busy(void);
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extern void thaw_workqueues(void);
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#endif /* CONFIG_FREEZER */
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#endif
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