From: Claudiu Manoil claudiu.manoil@nxp.com
[ 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 --- drivers/net/ethernet/freescale/gianfar.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/ethernet/freescale/gianfar.c +++ b/drivers/net/ethernet/freescale/gianfar.c @@ -1388,7 +1388,7 @@ static int gfar_probe(struct platform_de
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++) {