Commit e57b8bdb4833 ("igb: Add 1588 support to I210/I211.") enables
per-packet Rx timestamping by setting RXPBS.CFG_TS_EN with Rx queues
running. On i210/i211, CFG_TS_EN makes the DMA engine prepend a 16-byte
timestamp header to every Rx packet buffer and sets RXDADV_STAT_TSIP in the
Rx descriptor so igb_clean_rx_irq() strips it.
Setting CFG_TS_EN changes the buffer layout of already-armed descriptors.
Without a pipeline handshake, descriptor status and packet buffer layout
disagree for in-flight packets:
header inserted, no TSIP -> unstripped, frame shifted 16 bytes right
TSIP set, no header -> 16 bytes stripped, buffer tail appended
In both cases the Ethernet header is corrupted, causing protocol demux to
drop the frame silently. Because igb_alloc_mapped_page() allocates pages
without __GFP_ZERO, the second case appends uninitialized memory.
This occurs reliably on i210/i211 under traffic when requesting hardware
timestamps at runtime, yielding corrupt frames on off-to-on transitions.
Fix by bracketing the CFG_TS_EN transition with igb_down() and igb_up()
when the interface is running, ensuring the bit is only toggled with Rx
queues stopped.
Fixes: e57b8bdb4833 ("igb: Add 1588 support to I210/I211.")
Signed-off-by: Pascal Kneuper <[email protected]>
---
drivers/net/ethernet/intel/igb/igb_ptp.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c
b/drivers/net/ethernet/intel/igb/igb_ptp.c
index 638d8242b66bb..4da26e997f92c 100644
--- a/drivers/net/ethernet/intel/igb/igb_ptp.c
+++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
@@ -1283,9 +1283,26 @@ int igb_ptp_hwtstamp_set(struct net_device *netdev,
struct netlink_ext_ack *extack)
{
struct igb_adapter *adapter = netdev_priv(netdev);
+ struct e1000_hw *hw = &adapter->hw;
+ bool quiesce = false;
int err;
+ /* CFG_TS_EN changes the Rx buffer layout, so flipping it on a live
+ * queue leaves the descriptor and the data disagreeing about the
+ * 16 byte timestamp header for one window, mangling a frame.
+ */
+ if ((hw->mac.type == e1000_i210 || hw->mac.type == e1000_i211) &&
+ netif_running(netdev) &&
+ !(rd32(E1000_RXPBS) & E1000_RXPBS_CFG_TS_EN)) {
+ quiesce = true;
+ igb_down(adapter);
+ }
+
err = igb_ptp_set_timestamp_mode(adapter, config);
+
+ if (quiesce)
+ igb_up(adapter);
+
if (err)
return err;
--
2.47.3
