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timer: Generalize timer->base flags handling 

To prepare for addition of another flag, generalize timer->base flags
handling.

* Rename from TBASE_*_FLAG to TIMER_* and make them LU constants.

* Define and use TIMER_FLAG_MASK for flags masking so that multiple
  flags can be handled correctly.

* Don't dereference timer->base directly even if
  !tbase_get_deferrable().  All two such places are already passed in
  @base, so use it instead.

* Make sure tvec_base's alignment is large enough for timer->base
  flags using BUILD_BUG_ON().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: torvalds@linux-foundation.org
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/1344449428-24962-2-git-send-email-tj@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Tejun Heo 2012-08-08 11:10:25 -07:00 committed by Thomas Gleixner
parent eec19d1a0d
commit e52b1db37b
2 changed files with 17 additions and 10 deletions
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6
include/linux/timer.h
View File

@ -58,7 +58,9 @@ extern struct tvec_base boot_tvec_bases;
* the timer will be serviced when the CPU eventually wakes up with a * the timer will be serviced when the CPU eventually wakes up with a
* subsequent non-deferrable timer. * subsequent non-deferrable timer.
*/ */
#define TBASE_DEFERRABLE_FLAG (0x1) #define TIMER_DEFERRABLE 0x1LU
#define TIMER_FLAG_MASK 0x1LU
#define TIMER_INITIALIZER(_function, _expires, _data) { \ #define TIMER_INITIALIZER(_function, _expires, _data) { \
.entry = { .prev = TIMER_ENTRY_STATIC }, \ .entry = { .prev = TIMER_ENTRY_STATIC }, \
@ -72,7 +74,7 @@ extern struct tvec_base boot_tvec_bases;
} }
#define TBASE_MAKE_DEFERRED(ptr) ((struct tvec_base *) \ #define TBASE_MAKE_DEFERRED(ptr) ((struct tvec_base *) \
((unsigned char *)(ptr) + TBASE_DEFERRABLE_FLAG)) ((unsigned char *)(ptr) + TIMER_DEFERRABLE))
#define TIMER_DEFERRED_INITIALIZER(_function, _expires, _data) {\ #define TIMER_DEFERRED_INITIALIZER(_function, _expires, _data) {\
.entry = { .prev = TIMER_ENTRY_STATIC }, \ .entry = { .prev = TIMER_ENTRY_STATIC }, \

21
kernel/timer.c
View File

@ -92,12 +92,12 @@ static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
/* Functions below help us manage 'deferrable' flag */ /* Functions below help us manage 'deferrable' flag */
static inline unsigned int tbase_get_deferrable(struct tvec_base *base) static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
{ {
return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG); return ((unsigned int)(unsigned long)base & TIMER_DEFERRABLE);
} }
static inline struct tvec_base *tbase_get_base(struct tvec_base *base) static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
{ {
return ((struct tvec_base *)((unsigned long)base & ~TBASE_DEFERRABLE_FLAG)); return ((struct tvec_base *)((unsigned long)base & ~TIMER_FLAG_MASK));
} }
static inline void timer_set_deferrable(struct timer_list *timer) static inline void timer_set_deferrable(struct timer_list *timer)
@ -108,8 +108,9 @@ static inline void timer_set_deferrable(struct timer_list *timer)
static inline void static inline void
timer_set_base(struct timer_list *timer, struct tvec_base *new_base) timer_set_base(struct timer_list *timer, struct tvec_base *new_base)
{ {
timer->base = (struct tvec_base *)((unsigned long)(new_base) | unsigned long flags = (unsigned long)timer->base & TIMER_FLAG_MASK;
tbase_get_deferrable(timer->base));
timer->base = (struct tvec_base *)((unsigned long)(new_base) | flags);
} }
static unsigned long round_jiffies_common(unsigned long j, int cpu, static unsigned long round_jiffies_common(unsigned long j, int cpu,
@ -686,7 +687,7 @@ detach_expired_timer(struct timer_list *timer, struct tvec_base *base)
{ {
detach_timer(timer, true); detach_timer(timer, true);
if (!tbase_get_deferrable(timer->base)) if (!tbase_get_deferrable(timer->base))
timer->base->active_timers--; base->active_timers--;
} }
static int detach_if_pending(struct timer_list *timer, struct tvec_base *base, static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
@ -697,7 +698,7 @@ static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
detach_timer(timer, clear_pending); detach_timer(timer, clear_pending);
if (!tbase_get_deferrable(timer->base)) { if (!tbase_get_deferrable(timer->base)) {
timer->base->active_timers--; base->active_timers--;
if (timer->expires == base->next_timer) if (timer->expires == base->next_timer)
base->next_timer = base->timer_jiffies; base->next_timer = base->timer_jiffies;
} }
@ -1800,9 +1801,13 @@ static struct notifier_block __cpuinitdata timers_nb = {
void __init init_timers(void) void __init init_timers(void)
{ {
int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE, int err;
(void *)(long)smp_processor_id());
/* ensure there are enough low bits for flags in timer->base pointer */
BUILD_BUG_ON(__alignof__(struct tvec_base) & TIMER_FLAG_MASK);
err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
(void *)(long)smp_processor_id());
init_timer_stats(); init_timer_stats();
BUG_ON(err != NOTIFY_OK); BUG_ON(err != NOTIFY_OK);