I missed that there are different rules for drivers/net. Apologies. regards, Kyle On Fri, Mar 13, 2015 at 02:16:27PM -0400, Kyle McMartin wrote: > From: Iyappan Subramanian <isubramanian@xxxxxxx> > > This patch fixes the following kernel crash, > > WARNING: CPU: 2 PID: 0 at net/ipv4/tcp_input.c:3079 tcp_clean_rtx_queue+0x658/0x80c() > Call trace: > [<fffffe0000096b7c>] dump_backtrace+0x0/0x184 > [<fffffe0000096d10>] show_stack+0x10/0x1c > [<fffffe0000685ea0>] dump_stack+0x74/0x98 > [<fffffe00000b44e0>] warn_slowpath_common+0x88/0xb0 > [<fffffe00000b461c>] warn_slowpath_null+0x14/0x20 > [<fffffe00005b5c1c>] tcp_clean_rtx_queue+0x654/0x80c > [<fffffe00005b6228>] tcp_ack+0x454/0x688 > [<fffffe00005b6ca8>] tcp_rcv_established+0x4a4/0x62c > [<fffffe00005bf4b4>] tcp_v4_do_rcv+0x16c/0x350 > [<fffffe00005c225c>] tcp_v4_rcv+0x8e8/0x904 > [<fffffe000059d470>] ip_local_deliver_finish+0x100/0x26c > [<fffffe000059dad8>] ip_local_deliver+0xac/0xc4 > [<fffffe000059d6c4>] ip_rcv_finish+0xe8/0x328 > [<fffffe000059dd3c>] ip_rcv+0x24c/0x38c > [<fffffe0000563950>] __netif_receive_skb_core+0x29c/0x7c8 > [<fffffe0000563ea4>] __netif_receive_skb+0x28/0x7c > [<fffffe0000563f54>] netif_receive_skb_internal+0x5c/0xe0 > [<fffffe0000564810>] napi_gro_receive+0xb4/0x110 > [<fffffe0000482a2c>] xgene_enet_process_ring+0x144/0x338 > [<fffffe0000482d18>] xgene_enet_napi+0x1c/0x50 > [<fffffe0000565454>] net_rx_action+0x154/0x228 > [<fffffe00000b804c>] __do_softirq+0x110/0x28c > [<fffffe00000b8424>] irq_exit+0x8c/0xc0 > [<fffffe0000093898>] handle_IRQ+0x44/0xa8 > [<fffffe000009032c>] gic_handle_irq+0x38/0x7c > [...] > > Software writes poison data into the descriptor bytes[15:8] and upon > receiving the interrupt, if those bytes are overwritten by the hardware with > the valid data, software also reads bytes[7:0] and executes receive/tx > completion logic. > > If the CPU executes the above two reads in out of order fashion, then the > bytes[7:0] will have older data and causing the kernel panic. We have to > force the order of the reads and thus this patch introduces read memory > barrier between these reads. > > Signed-off-by: Iyappan Subramanian <isubramanian@xxxxxxx> > Signed-off-by: Keyur Chudgar <kchudgar@xxxxxxx> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> > [kyle: modified to rmb() since dma_rmb() is not in 3.18] > Signed-off-by: Kyle McMartin <kyle@xxxxxxxxxx> > --- > > drivers/net/ethernet/apm/xgene/xgene_enet_main.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c > index 83a5028..793f3b7 100644 > --- a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c > +++ b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c > @@ -369,6 +369,8 @@ static int xgene_enet_process_ring(struct xgene_enet_desc_ring *ring, > if (unlikely(xgene_enet_is_desc_slot_empty(raw_desc))) > break; > > + /* read fpqnum field after dataaddr field */ > + rmb(); > if (is_rx_desc(raw_desc)) > ret = xgene_enet_rx_frame(ring, raw_desc); > else > -- > 2.1.0 > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html