diff options
| -rw-r--r-- | include/linux/seqlock.h | 55 | ||||
| -rw-r--r-- | include/net/neighbour.h | 2 |
2 files changed, 46 insertions, 11 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 3e1f3f93dd18..a1dbf48d41f4 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -125,18 +125,30 @@ static inline int read_seqcount_retry(const seqcount_t *s, unsigned start) * Sequence counter only version assumes that callers are using their * own mutexing. */ -static inline void write_seqcount_begin(seqcount_t *s) +static inline void __write_seqcount_begin(seqcount_t *s) { s->sequence++; smp_wmb(); } -static inline void write_seqcount_end(seqcount_t *s) +static inline void write_seqcount_begin(seqcount_t *s) +{ + preempt_disable_rt(); + __write_seqcount_begin(s); +} + +static inline void __write_seqcount_end(seqcount_t *s) { smp_wmb(); s->sequence++; } +static inline void write_seqcount_end(seqcount_t *s) +{ + __write_seqcount_end(s); + preempt_enable_rt(); +} + /** * write_seqcount_barrier - invalidate in-progress read-side seq operations * @s: pointer to seqcount_t @@ -177,10 +189,33 @@ typedef struct { /* * Read side functions for starting and finalizing a read side section. */ +#ifndef CONFIG_PREEMPT_RT_FULL static inline unsigned read_seqbegin(const seqlock_t *sl) { return read_seqcount_begin(&sl->seqcount); } +#else +/* + * Starvation safe read side for RT + */ +static inline unsigned read_seqbegin(seqlock_t *sl) +{ + unsigned ret; + +repeat: + ret = sl->seqcount.sequence; + if (unlikely(ret & 1)) { + /* + * Take the lock and let the writer proceed (i.e. evtl + * boost it), otherwise we could loop here forever. + */ + spin_lock(&sl->lock); + spin_unlock(&sl->lock); + goto repeat; + } + return ret; +} +#endif static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start) { @@ -195,36 +230,36 @@ static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start) static inline void write_seqlock(seqlock_t *sl) { spin_lock(&sl->lock); - write_seqcount_begin(&sl->seqcount); + __write_seqcount_begin(&sl->seqcount); } static inline void write_sequnlock(seqlock_t *sl) { - write_seqcount_end(&sl->seqcount); + __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); + __write_seqcount_begin(&sl->seqcount); } static inline void write_sequnlock_bh(seqlock_t *sl) { - write_seqcount_end(&sl->seqcount); + __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); + __write_seqcount_begin(&sl->seqcount); } static inline void write_sequnlock_irq(seqlock_t *sl) { - write_seqcount_end(&sl->seqcount); + __write_seqcount_end(&sl->seqcount); spin_unlock_irq(&sl->lock); } @@ -233,7 +268,7 @@ static inline unsigned long __write_seqlock_irqsave(seqlock_t *sl) unsigned long flags; spin_lock_irqsave(&sl->lock, flags); - write_seqcount_begin(&sl->seqcount); + __write_seqcount_begin(&sl->seqcount); return flags; } @@ -243,7 +278,7 @@ static inline unsigned long __write_seqlock_irqsave(seqlock_t *sl) static inline void write_sequnlock_irqrestore(seqlock_t *sl, unsigned long flags) { - write_seqcount_end(&sl->seqcount); + __write_seqcount_end(&sl->seqcount); spin_unlock_irqrestore(&sl->lock, flags); } diff --git a/include/net/neighbour.h b/include/net/neighbour.h index 34c996f46181..8e626fa6ccde 100644 --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -394,7 +394,7 @@ struct neighbour_cb { #define NEIGH_CB(skb) ((struct neighbour_cb *)(skb)->cb) -static inline void neigh_ha_snapshot(char *dst, const struct neighbour *n, +static inline void neigh_ha_snapshot(char *dst, struct neighbour *n, const struct net_device *dev) { unsigned int seq; |