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authorJonathan Neuschäfer <j.neuschaefer@gmx.net>2018-06-08 21:16:14 +0200
committerJonathan Neuschäfer <j.neuschaefer@gmx.net>2018-06-08 21:41:21 +0200
commitd142a02a5f5ceafb5a5fc637e13ac1de8eef1ddf (patch)
treef577757e2321c2d323d089947b1943016a58faab /src
parentmessages: Ensure that there are more queue slots than CPUs (diff)
downloadwireguard-monolithic-historical-d142a02a5f5ceafb5a5fc637e13ac1de8eef1ddf.tar.xz
wireguard-monolithic-historical-d142a02a5f5ceafb5a5fc637e13ac1de8eef1ddf.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>
Diffstat (limited to 'src')
-rw-r--r--src/mpmc_ptr_ring.h16
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]);