* [PATCH net] net: ethernet: mvneta: fix MVNETA_SKB_HEADROOM alignment
@ 2020-06-05 12:53 Alexander Lobakin
2020-06-05 20:13 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Alexander Lobakin @ 2020-06-05 12:53 UTC (permalink / raw)
To: David S. Miller, Jakub Kicinski
Cc: Thomas Petazzoni, Alexei Starovoitov, Daniel Borkmann,
Jesper Dangaard Brouer, John Fastabend, Sven Auhagen,
Alexander Lobakin, netdev, linux-kernel, bpf
Commit ca23cb0bc50f ("mvneta: MVNETA_SKB_HEADROOM set last 3 bits to zero")
added headroom alignment check against 8.
Hovewer (if we imagine that NET_SKB_PAD or XDP_PACKET_HEADROOM is not
aligned to cacheline size), it actually aligns headroom down, while
skb/xdp_buff headroom should be *at least* equal to one of the values
(depending on XDP prog presence).
So, fix the check to align the value up. This satisfies both
hardware/driver and network stack requirements.
Fixes: ca23cb0bc50f ("mvneta: MVNETA_SKB_HEADROOM set last 3 bits to zero")
Signed-off-by: Alexander Lobakin <bloodyreaper@yandex.ru>
---
drivers/net/ethernet/marvell/mvneta.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 011cd26953d9..4cc9abd61c43 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -325,7 +325,7 @@
cache_line_size())
/* Driver assumes that the last 3 bits are 0 */
-#define MVNETA_SKB_HEADROOM (max(XDP_PACKET_HEADROOM, NET_SKB_PAD) & ~0x7)
+#define MVNETA_SKB_HEADROOM ALIGN(max(NET_SKB_PAD, XDP_PACKET_HEADROOM), 8)
#define MVNETA_SKB_PAD (SKB_DATA_ALIGN(sizeof(struct skb_shared_info) + \
MVNETA_SKB_HEADROOM))
#define MVNETA_SKB_SIZE(len) (SKB_DATA_ALIGN(len) + MVNETA_SKB_PAD)
--
2.27.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] net: ethernet: mvneta: fix MVNETA_SKB_HEADROOM alignment
2020-06-05 12:53 [PATCH net] net: ethernet: mvneta: fix MVNETA_SKB_HEADROOM alignment Alexander Lobakin
@ 2020-06-05 20:13 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2020-06-05 20:13 UTC (permalink / raw)
To: bloodyreaper
Cc: kuba, thomas.petazzoni, ast, daniel, hawk, john.fastabend,
sven.auhagen, netdev, linux-kernel, bpf
From: Alexander Lobakin <bloodyreaper@yandex.ru>
Date: Fri, 5 Jun 2020 15:53:24 +0300
> Commit ca23cb0bc50f ("mvneta: MVNETA_SKB_HEADROOM set last 3 bits to zero")
> added headroom alignment check against 8.
> Hovewer (if we imagine that NET_SKB_PAD or XDP_PACKET_HEADROOM is not
> aligned to cacheline size), it actually aligns headroom down, while
> skb/xdp_buff headroom should be *at least* equal to one of the values
> (depending on XDP prog presence).
> So, fix the check to align the value up. This satisfies both
> hardware/driver and network stack requirements.
>
> Fixes: ca23cb0bc50f ("mvneta: MVNETA_SKB_HEADROOM set last 3 bits to zero")
> Signed-off-by: Alexander Lobakin <bloodyreaper@yandex.ru>
Applied, thank you.
^ permalink raw reply [flat|nested] 2+ messages in thread
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