__ptr_ring_will_invalidate is useful if the caller would like to act before entries of the ptr_ring get invalidated by __ptr_ring_discard_one.
__ptr_ring_consume calls the new method and passes the result to __ptr_ring_discard_one, preserving the pre-patch logic. Co-developed-by: Tim Gebauer <[email protected]> Signed-off-by: Tim Gebauer <[email protected]> Signed-off-by: Simon Schippers <[email protected]> --- include/linux/ptr_ring.h | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h index c45e95071d7e..78fb3efedc7a 100644 --- a/include/linux/ptr_ring.h +++ b/include/linux/ptr_ring.h @@ -266,7 +266,22 @@ static inline bool ptr_ring_empty_bh(struct ptr_ring *r) } /* Must only be called after __ptr_ring_peek returned !NULL */ -static inline void __ptr_ring_discard_one(struct ptr_ring *r) +static inline bool __ptr_ring_will_invalidate(struct ptr_ring *r) +{ + /* Once we have processed enough entries invalidate them in + * the ring all at once so producer can reuse their space in the ring. + * We also do this when we reach end of the ring - not mandatory + * but helps keep the implementation simple. + */ + int consumer_head = r->consumer_head + 1; + + return consumer_head - r->consumer_tail >= r->batch || + consumer_head >= r->size; +} + +/* Must only be called after __ptr_ring_peek returned !NULL */ +static inline void __ptr_ring_discard_one(struct ptr_ring *r, + bool invalidate) { /* Fundamentally, what we want to do is update consumer * index and zero out the entry so producer can reuse it. @@ -286,13 +301,7 @@ static inline void __ptr_ring_discard_one(struct ptr_ring *r) int consumer_head = r->consumer_head; int head = consumer_head++; - /* Once we have processed enough entries invalidate them in - * the ring all at once so producer can reuse their space in the ring. - * We also do this when we reach end of the ring - not mandatory - * but helps keep the implementation simple. - */ - if (unlikely(consumer_head - r->consumer_tail >= r->batch || - consumer_head >= r->size)) { + if (unlikely(invalidate)) { /* Zero out entries in the reverse order: this way we touch the * cache line that producer might currently be reading the last; * producer won't make progress and touch other cache lines @@ -312,6 +321,7 @@ static inline void __ptr_ring_discard_one(struct ptr_ring *r) static inline void *__ptr_ring_consume(struct ptr_ring *r) { + bool invalidate; void *ptr; /* The READ_ONCE in __ptr_ring_peek guarantees that anyone @@ -319,8 +329,10 @@ static inline void *__ptr_ring_consume(struct ptr_ring *r) * with smp_wmb in __ptr_ring_produce. */ ptr = __ptr_ring_peek(r); - if (ptr) - __ptr_ring_discard_one(r); + if (ptr) { + invalidate = __ptr_ring_will_invalidate(r); + __ptr_ring_discard_one(r, invalidate); + } return ptr; } -- 2.43.0
