diff options
| author |   Jonathan Neuschäfer <j.neuschaefer@gmx.net> | 2018-06-08 21:16:14 +0200 |
|---|---|---|
| committer |   Thomas Gschwantner <tharre3@gmail.com> | 2018-06-22 14:52:22 +0200 |
| commit | 43dc2f6394e675b12abb8f384dcd8b3a4d468820 (patch) | |
| tree | 3031cf5bf19427a11329c2db4ea69b169348fcbe | |
| parent | messages: Ensure that there are more queue slots than CPUs (diff) | |
| download | wireguard-monolithic-historical-43dc2f6394e675b12abb8f384dcd8b3a4d468820.tar.xz wireguard-monolithic-historical-43dc2f6394e675b12abb8f384dcd8b3a4d468820.zip | |
mpmc_ptr_ring: Switch to smp_[rw]mb()
From https://www.kernel.org/doc/Documentation/memory-barriers.txt:
> SMP memory barriers are reduced to compiler barriers on uniprocessor
> compiled systems because it is assumed that a CPU will appear to be
> self-consistent, and will order overlapping accesses correctly with
> respect to itself.
Since we only order CPU memory accesses with the memory barriers in
mpmc_ptr_ring.h, smp_[rw]mb() should be sufficient.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
| -rw-r--r-- | src/mpmc_ptr_ring.h | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/src/mpmc_ptr_ring.h b/src/mpmc_ptr_ring.h index 267d10d..3a59bf1 100644 --- a/src/mpmc_ptr_ring.h +++ b/src/mpmc_ptr_ring.h @@ -52,7 +52,7 @@ static inline bool mpmc_ptr_ring_empty(struct mpmc_ptr_ring *r) size_t ptail, chead; /* Order the following reads against earlier stuff */ - rmb(); + smp_rmb(); ptail = atomic_read(&r->producer_tail); chead = atomic_read(&r->consumer_head); @@ -68,7 +68,7 @@ static inline int mpmc_ptr_ring_produce(struct mpmc_ptr_ring *r, void *ptr) p = atomic_read(&r->producer_head); for (;;) { - rmb(); /* TODO */ + smp_rmb(); /* TODO */ c = atomic_read(&r->consumer_head); if ((p - c) < mask) { /* fast path */ @@ -77,7 +77,7 @@ static inline int mpmc_ptr_ring_produce(struct mpmc_ptr_ring *r, void *ptr) } else { size_t new_p; - rmb(); + smp_rmb(); new_p = atomic_read(&r->producer_head); if (new_p == p) @@ -97,7 +97,7 @@ static inline int mpmc_ptr_ring_produce(struct mpmc_ptr_ring *r, void *ptr) * Make sure the WRITE_ONCE above becomes visible before producer_tail * is updated. */ - wmb(); + smp_wmb(); atomic_set(&r->producer_tail, p + 1); return 0; @@ -113,7 +113,7 @@ static inline void *mpmc_ptr_ring_consume(struct mpmc_ptr_ring *r) c = atomic_read(&r->consumer_head); /* Fetch consumer_head first. */ - rmb(); + smp_rmb(); p = atomic_read(&r->producer_tail); @@ -124,7 +124,7 @@ static inline void *mpmc_ptr_ring_consume(struct mpmc_ptr_ring *r) element = READ_ONCE(r->queue[c & mask]); /* TODO: Why? */ - rmb(); + smp_rmb(); old_c = atomic_cmpxchg(&r->consumer_head, c, c + 1); if (old_c == c) @@ -180,7 +180,7 @@ static inline void *__mpmc_ptr_ring_peek(struct mpmc_ptr_ring *r) c = atomic_read(&r->consumer_head); /* Fetch consumer_head first */ - rmb(); + smp_rmb(); p = atomic_read(&r->producer_tail); @@ -188,7 +188,7 @@ static inline void *__mpmc_ptr_ring_peek(struct mpmc_ptr_ring *r) return NULL; /* TODO */ - rmb(); + smp_rmb(); element = READ_ONCE(r->queue[c & mask]); |