raw_seqlock_t will be used to annotate seqlocks (e.g. xtime_lock) which can not be converted to sleeping locks in preempt-rt. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- include/linux/seqlock.h | 81 ++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 79 insertions(+), 2 deletions(-) Index: linux-2.6-tip/include/linux/seqlock.h =================================================================== --- linux-2.6-tip.orig/include/linux/seqlock.h +++ linux-2.6-tip/include/linux/seqlock.h @@ -31,9 +31,29 @@ typedef struct { unsigned sequence; + raw_spinlock_t lock; +} raw_seqlock_t; + +typedef struct { + unsigned sequence; spinlock_t lock; } seqlock_t; +#define __RAW_SEQLOCK_UNLOCKED(lockname) \ + { 0, __RAW_SPIN_LOCK_UNLOCKED(lockname) } + +#define raw_seqlock_init(x) \ + do { \ + (x)->sequence = 0; \ + raw_spin_lock_init(&(x)->lock); \ + } while (0) + +#define DEFINE_RAW_SEQLOCK(x) \ + raw_seqlock_t x = __RAW_SEQLOCK_UNLOCKED(x) + +#define __SEQLOCK_UNLOCKED(lockname) \ + { 0, __SPIN_LOCK_UNLOCKED(lockname) } + /* * These macros triggered gcc-3.x compile-time problems. We think these are * OK now. Be cautious. @@ -48,12 +68,19 @@ typedef struct { } while (0) #define DEFINE_SEQLOCK(x) \ - seqlock_t x = __SEQLOCK_UNLOCKED(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_raw_seqlock(raw_seqlock_t *sl) +{ + raw_spin_lock(&sl->lock); + ++sl->sequence; + smp_wmb(); +} + static inline void write_seqlock(seqlock_t *sl) { spin_lock(&sl->lock); @@ -61,6 +88,13 @@ static inline void write_seqlock(seqlock smp_wmb(); } +static inline void write_raw_sequnlock(raw_seqlock_t *sl) +{ + smp_wmb(); + sl->sequence++; + raw_spin_unlock(&sl->lock); +} + static inline void write_sequnlock(seqlock_t *sl) { smp_wmb(); @@ -80,6 +114,21 @@ static inline int write_tryseqlock(seqlo } /* Start of read calculation -- fetch last complete writer token */ +static __always_inline unsigned read_raw_seqbegin(const raw_seqlock_t *sl) +{ + unsigned ret; + +repeat: + ret = sl->sequence; + smp_rmb(); + if (unlikely(ret & 1)) { + cpu_relax(); + goto repeat; + } + + return ret; +} + static __always_inline unsigned read_seqbegin(const seqlock_t *sl) { unsigned ret; @@ -100,6 +149,14 @@ repeat: * * If sequence value changed then writer changed data while in section. */ +static __always_inline int +read_raw_seqretry(const raw_seqlock_t *sl, unsigned start) +{ + smp_rmb(); + + return (sl->sequence != start); +} + static __always_inline int read_seqretry(const seqlock_t *sl, unsigned start) { smp_rmb(); @@ -167,12 +224,32 @@ static inline void write_seqcount_end(se /* * Possible sw/hw IRQ protected versions of the interfaces. */ +#define write_raw_seqlock_irqsave(lock, flags) \ + do { local_irq_save(flags); write_raw_seqlock(lock); } while (0) +#define write_raw_seqlock_irq(lock) \ + do { local_irq_disable(); write_raw_seqlock(lock); } while (0) + +#define write_raw_sequnlock_irqrestore(lock, flags) \ + do { write_raw_sequnlock(lock); local_irq_restore(flags); } while(0) +#define write_raw_sequnlock_irq(lock) \ + do { write_raw_sequnlock(lock); local_irq_enable(); } while(0) + +#define read_raw_seqbegin_irqsave(lock, flags) \ + ({ local_irq_save(flags); read_raw_seqbegin(lock); }) + +#define read_raw_seqretry_irqrestore(lock, iv, flags) \ + ({ \ + int ret = read_raw_seqretry(lock, iv); \ + local_irq_restore(flags); \ + ret; \ + }) + #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) + do { local_bh_disable(); write_seqlock(lock); } while (0) #define write_sequnlock_irqrestore(lock, flags) \ do { write_sequnlock(lock); local_irq_restore(flags); } while(0) -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html