path: root/drivers/net/ethernet/ezchip/nps_enet.h
diff options
authorElad Kanfi <eladkan@mellanox.com>2016-05-09 20:13:19 +0300
committerDavid S. Miller <davem@davemloft.net>2016-05-10 15:04:49 -0400
commite5df49d564fe993c68f5cff6d96972a6358b4958 (patch)
tree899ce25dfc99e15b7454b845a894dabfd4e3d1dd /drivers/net/ethernet/ezchip/nps_enet.h
parentd99079e2fbd5ac38884f498ca99435d525152a88 (diff)
net: nps_enet: Tx handler synchronization
Below is a description of a possible problematic sequence. CPU-A is sending a frame and CPU-B handles the interrupt that indicates the frame was sent. CPU-B reads an invalid value of tx_packet_sent. CPU-A CPU-B ----- ----- nps_enet_send_frame . . tx_skb = skb tx_packet_sent = true order HW to start tx . . HW complete tx ------> get tx complete interrupt . . if(tx_packet_sent == true) handle tx_skb end memory transaction (tx_packet_sent actually written) Furthermore there is a dependency between tx_skb and tx_packet_sent. There is no assurance that tx_skb contains a valid pointer at CPU B when it sees tx_packet_sent == true. Solution: Initialize tx_skb to NULL and use it to indicate that packet was sent, in this way tx_packet_sent can be removed. Add a write memory barrier after setting tx_skb in order to make sure that it is valid before HW is informed and IRQ is fired. Fixed sequence will be: CPU-A CPU-B ----- ----- tx_skb = skb wmb() . . order HW to start tx . . HW complete tx ------> get tx complete interrupt . . if(tx_skb != NULL) handle tx_skb tx_skb = NULL Signed-off-by: Elad Kanfi <eladkan@mellanox.com> Acked-by: Noam Camus <noamca@mellanox.com> Acked-by: Gilad Ben-Yossef <giladby@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/ezchip/nps_enet.h')
1 files changed, 0 insertions, 2 deletions
diff --git a/drivers/net/ethernet/ezchip/nps_enet.h b/drivers/net/ethernet/ezchip/nps_enet.h
index d0cab600bce8..3939ca20cc9f 100644
--- a/drivers/net/ethernet/ezchip/nps_enet.h
+++ b/drivers/net/ethernet/ezchip/nps_enet.h
@@ -165,14 +165,12 @@
* struct nps_enet_priv - Storage of ENET's private information.
* @regs_base: Base address of ENET memory-mapped control registers.
* @irq: For RX/TX IRQ number.
- * @tx_packet_sent: SW indication if frame is being sent.
* @tx_skb: socket buffer of sent frame.
* @napi: Structure for NAPI.
struct nps_enet_priv {
void __iomem *regs_base;
s32 irq;
- bool tx_packet_sent;
struct sk_buff *tx_skb;
struct napi_struct napi;
u32 ge_mac_cfg_2_value;