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distributor: fix handshake synchronization

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rte_distributor_return_pkt function which is run on worker cores
must wait for distributor core to clear handshake on retptr64
before using those buffers. While the handshake is set distributor
core controls buffers and any operations on worker side might overwrite
buffers which are unread yet.
Same situation appears in the legacy single distributor. Function
rte_distributor_return_pkt_single shouldn't modify the bufptr64 until
handshake on it is cleared by distributor lcore.

Fixes: 775003ad2f ("distributor: add new burst-capable library")
Cc: stable@dpdk.org

Signed-off-by: Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>
Acked-by: David Hunt <david.hunt@intel.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
This commit is contained in:
Lukasz Wojciechowski 2020-10-17 05:06:45 +02:00 committed by David Marchand
parent 894080cf8a
commit bea84d5592
2 changed files with 16 additions and 0 deletions
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12
lib/librte_distributor/rte_distributor.c
View File

@ -169,6 +169,18 @@ rte_distributor_return_pkt(struct rte_distributor *d,
return -EINVAL;
}
/* Spin while handshake bits are set (scheduler clears it).
* Sync with worker on GET_BUF flag.
*/
while (unlikely(__atomic_load_n(&(buf->retptr64[0]), __ATOMIC_RELAXED)
& RTE_DISTRIB_GET_BUF)) {
rte_pause();
uint64_t t = rte_rdtsc()+100;
while (rte_rdtsc() < t)
rte_pause();
}
/* Sync with distributor to acquire retptrs */
__atomic_thread_fence(__ATOMIC_ACQUIRE);
for (i = 0; i < RTE_DIST_BURST_SIZE; i++)

4
lib/librte_distributor/rte_distributor_single.c
View File

@ -74,6 +74,10 @@ rte_distributor_return_pkt_single(struct rte_distributor_single *d,
union rte_distributor_buffer_single *buf = &d->bufs[worker_id];
uint64_t req = (((int64_t)(uintptr_t)oldpkt) << RTE_DISTRIB_FLAG_BITS)
| RTE_DISTRIB_RETURN_BUF;
while (unlikely(__atomic_load_n(&buf->bufptr64, __ATOMIC_RELAXED)
& RTE_DISTRIB_FLAGS_MASK))
rte_pause();
/* Sync with distributor on RETURN_BUF flag. */
__atomic_store_n(&(buf->bufptr64), req, __ATOMIC_RELEASE);
return 0;