Gavin Hu 85cffb2ecc ring: enforce reading tail before slots ... In weak memory models, like arm64, reading the prod.tail may get reordered after reading the ring slots, which corrupts the ring and stale data is observed. This issue was reported by NXP on 8-A72 DPAA2 board. The problem is most likely caused by missing the acquire semantics when reading prod.tail (in SC dequeue) which makes it possible to read a stale value from the ring slots. For MP (and MC) case, rte_atomic32_cmpset() already provides the required ordering. For SP case, the control depependency between if-statement (which depends on the read of r->cons.tail) and the later stores to the ring slots make RMB unnecessary. About the control dependency, read more at: https://www.cl.cam.ac.uk/~pes20/ppc-supplemental/test7.pdf This patch is adding the required read barrier to prevent reading the ring slots get reordered before reading prod.tail for SC case. Fixes: c9fb3c6289 ("ring: move code in a new header file") Cc: stable@dpdk.org Signed-off-by: Gavin Hu <gavin.hu@arm.com> Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com> Tested-by: Nipun Gupta <nipun.gupta@nxp.com> Acked-by: Nipun Gupta <nipun.gupta@nxp.com> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>		2019-03-28 01:22:04 +01:00
..
Makefile	ring: relax alignment constraint on ring structure	2018-04-18 00:24:22 +02:00
meson.build	ring: add library version to meson build	2018-10-25 14:30:05 +02:00
rte_ring_c11_mem.h	ring/c11: relax ordering for load and store of the head	2018-11-13 17:00:58 +01:00
rte_ring_generic.h	ring: enforce reading tail before slots	2019-03-28 01:22:04 +01:00
rte_ring_version.map	lib: remove unused map symbols	2018-02-13 14:55:01 +01:00
rte_ring.c	ring: convert license headers to SPDX tags	2018-02-01 01:46:45 +01:00
rte_ring.h	config: rename option for C11 memory model	2018-10-26 18:09:22 +02:00