/*
* Marks given callback as used by datapath.
*/
static __rte_always_inline void
bpf_eth_cbi_inuse(struct bpf_eth_cbi *cbi)
{
- cbi->use++;
- /* make sure no store/load reordering could happen */
- rte_smp_mb();
+ rte_atomic_store_explicit(&cbi->use,
+ rte_atomic_load_explicit(&cbi->use, rte_memory_order_relaxed) +
1,
+ rte_memory_order_relaxed);
+
+ /* full barrier: count must be visible before cb is read */
+ rte_atomic_thread_fence(rte_memory_order_seq_cst);
This is correct but why use a barrier when the above store itself could
be SEQ_CST that
synchronizes with load in bpf_eth_cbi_wait?
}
/*
@@ -91,9 +106,10 @@ bpf_eth_cbi_inuse(struct bpf_eth_cbi *cbi)
static __rte_always_inline void
bpf_eth_cbi_unuse(struct bpf_eth_cbi *cbi)
{
- /* make sure all previous loads are completed */
- rte_smp_rmb();
- cbi->use++;
+ /* release: pairs with the acquire bpf_eth_cbi_wait() */
+ rte_atomic_store_explicit(&cbi->use,
+ rte_atomic_load_explicit(&cbi->use, rte_memory_order_relaxed) +
1,
+ rte_memory_order_release);
}
/*
@@ -104,15 +120,15 @@ bpf_eth_cbi_wait(const struct bpf_eth_cbi *cbi)
{
uint32_t puse;
- /* make sure all previous loads and stores are completed */
- rte_smp_mb();
+ /* full barrier: cleared cb must be visible before counter is read */
+ rte_atomic_thread_fence(rte_memory_order_seq_cst);
- puse = cbi->use;
+ puse = rte_atomic_load_explicit(&cbi->use, rte_memory_order_acquire);
/* in use, busy wait till current RX/TX iteration is finished */
if ((puse & BPF_ETH_CBI_INUSE) != 0) {
RTE_WAIT_UNTIL_MASKED((__rte_atomic uint32_t
*)(uintptr_t)&cbi->use,
- UINT32_MAX, !=, puse, rte_memory_order_relaxed);
+ UINT32_MAX, !=, puse, rte_memory_order_acquire);
}
}
@@ -439,7 +455,6 @@ bpf_eth_cbi_unload(struct bpf_eth_cbi *bc)
{
/* mark this cbi as empty */
bc->cb = NULL;
- rte_smp_mb();
/* make sure datapath doesn't use bpf anymore, then destroy bpf */
bpf_eth_cbi_wait(bc);
--wathsala
