drivers: net: cpsw: discard all packets received when interface is down

When the Ethernet interface is brought down during high Ethernet traffic,
then cpsw creates the following warn dump. When cpdma has already processed
the packet then the status will be greater than 0, so the cpsw_rx_handler
considers that the interface is up and try to resubmit one more rx buffer
to cpdma which fails as the DMA is in teardown process. This can be avoided
by checking the interface state and then process the received packet, if the
interface is down just discard and free the skb and return.

[ 2823.104591] WARNING: CPU: 0 PID: 1823 at drivers/net/ethernet/ti/cpsw.c:711 cpsw_rx_handler+0x148/0x164()
[ 2823.114654] Modules linked in:
[ 2823.117872] CPU: 0 PID: 1823 Comm: ifconfig Tainted: G        W     3.14.0-11992-gf34c4a3 #11
[ 2823.126860] [<c0014b5c>] (unwind_backtrace) from [<c00117e4>] (show_stack+0x10/0x14)
[ 2823.135030] [<c00117e4>] (show_stack) from [<c0533a9c>] (dump_stack+0x80/0x9c)
[ 2823.142619] [<c0533a9c>] (dump_stack) from [<c003f0e0>] (warn_slowpath_common+0x6c/0x90)
[ 2823.151141] [<c003f0e0>] (warn_slowpath_common) from [<c003f120>] (warn_slowpath_null+0x1c/0x24)
[ 2823.160336] [<c003f120>] (warn_slowpath_null) from [<c03caeb0>] (cpsw_rx_handler+0x148/0x164)
[ 2823.169314] [<c03caeb0>] (cpsw_rx_handler) from [<c03c730c>] (__cpdma_chan_free+0x90/0xa8)
[ 2823.178028] [<c03c730c>] (__cpdma_chan_free) from [<c03c7418>] (__cpdma_chan_process+0xf4/0x134)
[ 2823.187279] [<c03c7418>] (__cpdma_chan_process) from [<c03c7560>] (cpdma_chan_stop+0xb4/0x17c)
[ 2823.196349] [<c03c7560>] (cpdma_chan_stop) from [<c03c766c>] (cpdma_ctlr_stop+0x44/0x9c)
[ 2823.204872] [<c03c766c>] (cpdma_ctlr_stop) from [<c03cb708>] (cpsw_ndo_stop+0x154/0x188)
[ 2823.213321] [<c03cb708>] (cpsw_ndo_stop) from [<c046f0ec>] (__dev_close_many+0x84/0xc8)
[ 2823.221761] [<c046f0ec>] (__dev_close_many) from [<c046f158>] (__dev_close+0x28/0x3c)
[ 2823.230012] [<c046f158>] (__dev_close) from [<c0474ca8>] (__dev_change_flags+0x88/0x160)
[ 2823.238483] [<c0474ca8>] (__dev_change_flags) from [<c0474da0>] (dev_change_flags+0x18/0x48)
[ 2823.247316] [<c0474da0>] (dev_change_flags) from [<c04d12c4>] (devinet_ioctl+0x61c/0x6e0)
[ 2823.255884] [<c04d12c4>] (devinet_ioctl) from [<c045c660>] (sock_ioctl+0x68/0x2a4)
[ 2823.263789] [<c045c660>] (sock_ioctl) from [<c0125fe4>] (do_vfs_ioctl+0x78/0x61c)
[ 2823.271629] [<c0125fe4>] (do_vfs_ioctl) from [<c01265ec>] (SyS_ioctl+0x64/0x74)
[ 2823.279284] [<c01265ec>] (SyS_ioctl) from [<c000e580>] (ret_fast_syscall+0x0/0x48)

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 16e5c57da61cda26998bee91a327960ebd1562f6)
drivers: net: cpsw: enable interrupts after napi enable and clearing previous interrupts

When the Ethernet interface is put down and up with heavy Ethernet
traffic, then there is prossibility of an interrupt waiting in irq
controller to be processed, so when the interface is brought up again
just after enable interrupt, it goes to ISR due to the previous
unhandled interrutp and in ISR napi is not scheduled as the napi
is not enabled in ndo_open which results in disabled interrupt for
CPSW and no packets are received in cpsw. So this patch moves enabling
of interupts after napi_enable and clearing CPDMA interrupts.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit f63a975e8f07a75dbf0386402788330d0bebd8d8)
net: eth: cpsw: Use net_device_stats from struct net_device

Instead of using an own copy of struct net_device_stats in struct
cpsw_priv, use stats from struct net_device. Also remove the thus
unnecessary .ndo_get_stats function, as it just returns dev->stats,
which is the default.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 8dc43ddc9fe0af3a555af235a69a398c3eba2639)

Conflicts:
	drivers/net/ethernet/ti/cpsw.c