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seqlock: Use seqcount infrastructure

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No point in having different implementations for the same
thing. Change the macro mess to inline functions where possible.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2011-07-16 18:40:26 +02:00 committed by Ingo Molnar
parent 65c9d1bbc9
commit 6617feca15
1 changed files with 95 additions and 85 deletions
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180
include/linux/seqlock.h
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@ -30,81 +30,12 @@
#include <linux/preempt.h>
#include <asm/processor.h>
typedef struct {
unsigned sequence;
spinlock_t lock;
} seqlock_t;
/*
* These macros triggered gcc-3.x compile-time problems. We think these are
* OK now. Be cautious.
*/
#define __SEQLOCK_UNLOCKED(lockname) \
{ 0, __SPIN_LOCK_UNLOCKED(lockname) }
#define seqlock_init(x) \
do { \
(x)->sequence = 0; \
spin_lock_init(&(x)->lock); \
} while (0)
#define DEFINE_SEQLOCK(x) \
seqlock_t x = __SEQLOCK_UNLOCKED(x)
/* Lock out other writers and update the count.
* Acts like a normal spin_lock/unlock.
* Don't need preempt_disable() because that is in the spin_lock already.
*/
static inline void write_seqlock(seqlock_t *sl)
{
spin_lock(&sl->lock);
++sl->sequence;
smp_wmb();
}
static inline void write_sequnlock(seqlock_t *sl)
{
smp_wmb();
sl->sequence++;
spin_unlock(&sl->lock);
}
/* Start of read calculation -- fetch last complete writer token */
static __always_inline unsigned read_seqbegin(const seqlock_t *sl)
{
unsigned ret;
repeat:
ret = ACCESS_ONCE(sl->sequence);
if (unlikely(ret & 1)) {
cpu_relax();
goto repeat;
}
smp_rmb();
return ret;
}
/*
* Test if reader processed invalid data.
*
* If sequence value changed then writer changed data while in section.
*/
static __always_inline int read_seqretry(const seqlock_t *sl, unsigned start)
{
smp_rmb();
return unlikely(sl->sequence != start);
}
/*
* Version using sequence counter only.
* This can be used when code has its own mutex protecting the
* updating starting before the write_seqcountbeqin() and ending
* after the write_seqcount_end().
*/
typedef struct seqcount {
unsigned sequence;
} seqcount_t;
@ -207,7 +138,6 @@ static inline int __read_seqcount_retry(const seqcount_t *s, unsigned start)
static inline int read_seqcount_retry(const seqcount_t *s, unsigned start)
{
smp_rmb();
return __read_seqcount_retry(s, start);
}
@ -241,21 +171,101 @@ static inline void write_seqcount_barrier(seqcount_t *s)
s->sequence+=2;
}
/*
* Possible sw/hw IRQ protected versions of the interfaces.
*/
#define write_seqlock_irqsave(lock, flags) \
do { local_irq_save(flags); write_seqlock(lock); } while (0)
#define write_seqlock_irq(lock) \
do { local_irq_disable(); write_seqlock(lock); } while (0)
#define write_seqlock_bh(lock) \
do { local_bh_disable(); write_seqlock(lock); } while (0)
typedef struct {
struct seqcount seqcount;
spinlock_t lock;
} seqlock_t;
#define write_sequnlock_irqrestore(lock, flags) \
do { write_sequnlock(lock); local_irq_restore(flags); } while(0)
#define write_sequnlock_irq(lock) \
do { write_sequnlock(lock); local_irq_enable(); } while(0)
#define write_sequnlock_bh(lock) \
do { write_sequnlock(lock); local_bh_enable(); } while(0)
/*
* These macros triggered gcc-3.x compile-time problems. We think these are
* OK now. Be cautious.
*/
#define __SEQLOCK_UNLOCKED(lockname) \
{ \
.seqcount = SEQCNT_ZERO, \
.lock = __SPIN_LOCK_UNLOCKED(lockname) \
}
#define seqlock_init(x) \
do { \
seqcount_init(&(x)->seqcount); \
spin_lock_init(&(x)->lock); \
} while (0)
#define DEFINE_SEQLOCK(x) \
seqlock_t x = __SEQLOCK_UNLOCKED(x)
/*
* Read side functions for starting and finalizing a read side section.
*/
static inline unsigned read_seqbegin(const seqlock_t *sl)
{
return read_seqcount_begin(&sl->seqcount);
}
static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start)
{
return read_seqcount_retry(&sl->seqcount, start);
}
/*
* Lock out other writers and update the count.
* Acts like a normal spin_lock/unlock.
* Don't need preempt_disable() because that is in the spin_lock already.
*/
static inline void write_seqlock(seqlock_t *sl)
{
spin_lock(&sl->lock);
write_seqcount_begin(&sl->seqcount);
}
static inline void write_sequnlock(seqlock_t *sl)
{
write_seqcount_end(&sl->seqcount);
spin_unlock(&sl->lock);
}
static inline void write_seqlock_bh(seqlock_t *sl)
{
spin_lock_bh(&sl->lock);
write_seqcount_begin(&sl->seqcount);
}
static inline void write_sequnlock_bh(seqlock_t *sl)
{
write_seqcount_end(&sl->seqcount);
spin_unlock_bh(&sl->lock);
}
static inline void write_seqlock_irq(seqlock_t *sl)
{
spin_lock_irq(&sl->lock);
write_seqcount_begin(&sl->seqcount);
}
static inline void write_sequnlock_irq(seqlock_t *sl)
{
write_seqcount_end(&sl->seqcount);
spin_unlock_irq(&sl->lock);
}
static inline unsigned long __write_seqlock_irqsave(seqlock_t *sl)
{
unsigned long flags;
spin_lock_irqsave(&sl->lock, flags);
write_seqcount_begin(&sl->seqcount);
return flags;
}
#define write_seqlock_irqsave(lock, flags) \
do { flags = __write_seqlock_irqsave(lock); } while (0)
static inline void
write_sequnlock_irqrestore(seqlock_t *sl, unsigned long flags)
{
write_seqcount_end(&sl->seqcount);
spin_unlock_irqrestore(&sl->lock, flags);
}
#endif /* __LINUX_SEQLOCK_H */