timer: Permit statically-declared work with deferrable timers
Currently, you have to just define a delayed_work uninitialised, and then
initialise it before first use. That's a tad clumsy. At risk of playing
mind-games with the compiler, fooling it into doing pointer arithmetic
with compile-time-constants, this lets clients properly initialise delayed
work with deferrable timers statically.
This patch was inspired by the issues which lead Artem Bityutskiy to
commit 8eab945c56
("sunrpc: make the cache cleaner workqueue
deferrable").
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Acked-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
parent
2bf1c05e3c
commit
dd6414b50f
3 changed files with 34 additions and 14 deletions
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@ -48,6 +48,18 @@ extern struct tvec_base boot_tvec_bases;
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#define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn)
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#endif
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/*
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* Note that all tvec_bases are 2 byte aligned and lower bit of
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* base in timer_list is guaranteed to be zero. Use the LSB to
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* indicate whether the timer is deferrable.
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*
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* A deferrable timer will work normally when the system is busy, but
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* will not cause a CPU to come out of idle just to service it; instead,
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* the timer will be serviced when the CPU eventually wakes up with a
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* subsequent non-deferrable timer.
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*/
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#define TBASE_DEFERRABLE_FLAG (0x1)
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#define TIMER_INITIALIZER(_function, _expires, _data) { \
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.entry = { .prev = TIMER_ENTRY_STATIC }, \
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.function = (_function), \
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@ -59,6 +71,19 @@ extern struct tvec_base boot_tvec_bases;
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__FILE__ ":" __stringify(__LINE__)) \
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}
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#define TBASE_MAKE_DEFERRED(ptr) ((struct tvec_base *) \
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((unsigned char *)(ptr) + TBASE_DEFERRABLE_FLAG))
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#define TIMER_DEFERRED_INITIALIZER(_function, _expires, _data) {\
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.entry = { .prev = TIMER_ENTRY_STATIC }, \
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.function = (_function), \
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.expires = (_expires), \
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.data = (_data), \
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.base = TBASE_MAKE_DEFERRED(&boot_tvec_bases), \
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__TIMER_LOCKDEP_MAP_INITIALIZER( \
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__FILE__ ":" __stringify(__LINE__)) \
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}
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#define DEFINE_TIMER(_name, _function, _expires, _data) \
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struct timer_list _name = \
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TIMER_INITIALIZER(_function, _expires, _data)
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@ -127,12 +127,20 @@ struct execute_work {
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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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@ -88,18 +88,6 @@ struct tvec_base boot_tvec_bases;
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EXPORT_SYMBOL(boot_tvec_bases);
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static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
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/*
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* Note that all tvec_bases are 2 byte aligned and lower bit of
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* base in timer_list is guaranteed to be zero. Use the LSB to
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* indicate whether the timer is deferrable.
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*
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* A deferrable timer will work normally when the system is busy, but
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* will not cause a CPU to come out of idle just to service it; instead,
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* the timer will be serviced when the CPU eventually wakes up with a
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* subsequent non-deferrable timer.
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*/
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#define TBASE_DEFERRABLE_FLAG (0x1)
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/* Functions below help us manage 'deferrable' flag */
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static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
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{
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@ -113,8 +101,7 @@ static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
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static inline void timer_set_deferrable(struct timer_list *timer)
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{
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timer->base = ((struct tvec_base *)((unsigned long)(timer->base) |
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TBASE_DEFERRABLE_FLAG));
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timer->base = TBASE_MAKE_DEFERRED(timer->base);
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}
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static inline void
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