When enqueueing/dequeueing to/from the ring we try to optimize by manual
loop unrolling. The check for this optimization looks like:
if (likely(idx + n < size)) {
where 'idx' points to the first usable element (empty slot for enqueue,
data for dequeue). The correct comparison here should be '<=' instead
of '<'.
This is not a functional error since we fall back to the loop with
correct checks on indexes. Just a minor suboptimal behaviour for the
case when we want to enqueue/dequeue exactly the number of elements that
we have in the ring before wrapping to its beginning.
Fixes: cc4b218790f6 ("ring: support configurable element size")
Fixes: 286bd05bf70d ("ring: optimisations")
Signed-off-by: Andrzej Ostruszka <a...@semihalf.com>
Reviewed-by: Olivier Matz <olivier.m...@6wind.com>
Acked-by: Konstantin Ananyev <konstantin.anan...@intel.com>
---
lib/ring/rte_ring_elem_pvt.h | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/lib/ring/rte_ring_elem_pvt.h b/lib/ring/rte_ring_elem_pvt.h
index 275ec55393..83788c56e6 100644
--- a/lib/ring/rte_ring_elem_pvt.h
+++ b/lib/ring/rte_ring_elem_pvt.h
@@ -17,7 +17,7 @@ __rte_ring_enqueue_elems_32(struct rte_ring *r, const
uint32_t size,
unsigned int i;
uint32_t *ring = (uint32_t *)&r[1];
const uint32_t *obj = (const uint32_t *)obj_table;
- if (likely(idx + n < size)) {
+ if (likely(idx + n <= size)) {
for (i = 0; i < (n & ~0x7); i += 8, idx += 8) {
ring[idx] = obj[i];
ring[idx + 1] = obj[i + 1];
@@ -62,7 +62,7 @@ __rte_ring_enqueue_elems_64(struct rte_ring *r, uint32_t
prod_head,
uint32_t idx = prod_head & r->mask;
uint64_t *ring = (uint64_t *)&r[1];
const unaligned_uint64_t *obj = (const unaligned_uint64_t *)obj_table;
- if (likely(idx + n < size)) {
+ if (likely(idx + n <= size)) {
for (i = 0; i < (n & ~0x3); i += 4, idx += 4) {
ring[idx] = obj[i];
ring[idx + 1] = obj[i + 1];
@@ -95,7 +95,7 @@ __rte_ring_enqueue_elems_128(struct rte_ring *r, uint32_t
prod_head,
uint32_t idx = prod_head & r->mask;
rte_int128_t *ring = (rte_int128_t *)&r[1];
const rte_int128_t *obj = (const rte_int128_t *)obj_table;
- if (likely(idx + n < size)) {
+ if (likely(idx + n <= size)) {
for (i = 0; i < (n & ~0x1); i += 2, idx += 2)
memcpy((void *)(ring + idx),
(const void *)(obj + i), 32);
@@ -151,7 +151,7 @@ __rte_ring_dequeue_elems_32(struct rte_ring *r, const
uint32_t size,
unsigned int i;
uint32_t *ring = (uint32_t *)&r[1];
uint32_t *obj = (uint32_t *)obj_table;
- if (likely(idx + n < size)) {
+ if (likely(idx + n <= size)) {
for (i = 0; i < (n & ~0x7); i += 8, idx += 8) {
obj[i] = ring[idx];
obj[i + 1] = ring[idx + 1];
@@ -196,7 +196,7 @@ __rte_ring_dequeue_elems_64(struct rte_ring *r, uint32_t
prod_head,
uint32_t idx = prod_head & r->mask;
uint64_t *ring = (uint64_t *)&r[1];
unaligned_uint64_t *obj = (unaligned_uint64_t *)obj_table;
- if (likely(idx + n < size)) {
+ if (likely(idx + n <= size)) {
for (i = 0; i < (n & ~0x3); i += 4, idx += 4) {
obj[i] = ring[idx];
obj[i + 1] = ring[idx + 1];
@@ -229,7 +229,7 @@ __rte_ring_dequeue_elems_128(struct rte_ring *r, uint32_t
prod_head,
uint32_t idx = prod_head & r->mask;
rte_int128_t *ring = (rte_int128_t *)&r[1];
rte_int128_t *obj = (rte_int128_t *)obj_table;
- if (likely(idx + n < size)) {
+ if (likely(idx + n <= size)) {
for (i = 0; i < (n & ~0x1); i += 2, idx += 2)
memcpy((void *)(obj + i), (void *)(ring + idx), 32);
switch (n & 0x1) {
--
2.34.1.575.g55b058a8bb-goog
