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authorClaudiu Manoil <claudiu.manoil@nxp.com>2020-10-20 20:36:05 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-11-10 12:37:25 +0100
commit6ef3bcc25a3e85c1325398c3f605123715814b98 (patch)
tree1ec755c4f5c49aca6dba2469d616d343de3ded35 /drivers
parent5b66a5b6a9e239d1d1f84b74539f745d72d00f16 (diff)
gianfar: Account for Tx PTP timestamp in the skb headroom
[ Upstream commit d6a076d68c6b5d6a5800f3990a513facb7016dea ] When PTP timestamping is enabled on Tx, the controller inserts the Tx timestamp at the beginning of the frame buffer, between SFD and the L2 frame header. This means that the skb provided by the stack is required to have enough headroom otherwise a new skb needs to be created by the driver to accommodate the timestamp inserted by h/w. Up until now the driver was relying on the second option, using skb_realloc_headroom() to create a new skb to accommodate PTP frames. Turns out that this method is not reliable, as reallocation of skbs for PTP frames along with the required overhead (skb_set_owner_w, consume_skb) is causing random crashes in subsequent skb_*() calls, when multiple concurrent TCP streams are run at the same time on the same device (as seen in James' report). Note that these crashes don't occur with a single TCP stream, nor with multiple concurrent UDP streams, but only when multiple TCP streams are run concurrently with the PTP packet flow (doing skb reallocation). This patch enforces the first method, by requesting enough headroom from the stack to accommodate PTP frames, and so avoiding skb_realloc_headroom() & co, and the crashes no longer occur. There's no reason not to set needed_headroom to a large enough value to accommodate PTP frames, so in this regard this patch is a fix. Reported-by: James Jurack <james.jurack@ametek.com> Fixes: bee9e58c9e98 ("gianfar:don't add FCB length to hard_header_len") Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com> Link: https://lore.kernel.org/r/20201020173605.1173-1-claudiu.manoil@nxp.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/ethernet/freescale/gianfar.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index d1bcabeda049..5cb58ab1eec9 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -3369,7 +3369,7 @@ static int gfar_probe(struct platform_device *ofdev)
if (dev->features & NETIF_F_IP_CSUM ||
priv->device_flags & FSL_GIANFAR_DEV_HAS_TIMER)
- dev->needed_headroom = GMAC_FCB_LEN;
+ dev->needed_headroom = GMAC_FCB_LEN + GMAC_TXPAL_LEN;
/* Initializing some of the rx/tx queue level parameters */
for (i = 0; i < priv->num_tx_queues; i++) {