Merge branch 'macb-DMA-race-fixes'
Anssi Hannula says:
====================
net: macb: DMA race condition fixes
Here are a couple of race condition fixes for the macb driver. The first
two are for issues observed at runtime on real HW.
v2:
- added received Tested-bys and Acked-bys to the first two patches
- in patch 3/3, moved the timestamp protection barrier closer to the
timestamp reads
- in patch 3/3, removed unnecessary move of the addr assignment in
gem_rx() to keep the patch minimal for maximum clarity
- in patch 3/3, clarified commit message and comments
The 3/3 is the same one I improperly sent last week as a standalone
patch.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index dfaefe9..4c816e5 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -681,6 +681,11 @@ static void macb_set_addr(struct macb *bp, struct macb_dma_desc *desc, dma_addr_
if (bp->hw_dma_cap & HW_DMA_CAP_64B) {
desc_64 = macb_64b_desc(bp, desc);
desc_64->addrh = upper_32_bits(addr);
+ /* The low bits of RX address contain the RX_USED bit, clearing
+ * of which allows packet RX. Make sure the high bits are also
+ * visible to HW at that point.
+ */
+ dma_wmb();
}
#endif
desc->addr = lower_32_bits(addr);
@@ -929,14 +934,19 @@ static void gem_rx_refill(struct macb_queue *queue)
if (entry == bp->rx_ring_size - 1)
paddr |= MACB_BIT(RX_WRAP);
- macb_set_addr(bp, desc, paddr);
desc->ctrl = 0;
+ /* Setting addr clears RX_USED and allows reception,
+ * make sure ctrl is cleared first to avoid a race.
+ */
+ dma_wmb();
+ macb_set_addr(bp, desc, paddr);
/* properly align Ethernet header */
skb_reserve(skb, NET_IP_ALIGN);
} else {
- desc->addr &= ~MACB_BIT(RX_USED);
desc->ctrl = 0;
+ dma_wmb();
+ desc->addr &= ~MACB_BIT(RX_USED);
}
}
@@ -990,11 +1000,15 @@ static int gem_rx(struct macb_queue *queue, int budget)
rxused = (desc->addr & MACB_BIT(RX_USED)) ? true : false;
addr = macb_get_addr(bp, desc);
- ctrl = desc->ctrl;
if (!rxused)
break;
+ /* Ensure ctrl is at least as up-to-date as rxused */
+ dma_rmb();
+
+ ctrl = desc->ctrl;
+
queue->rx_tail++;
count++;
@@ -1169,11 +1183,14 @@ static int macb_rx(struct macb_queue *queue, int budget)
/* Make hw descriptor updates visible to CPU */
rmb();
- ctrl = desc->ctrl;
-
if (!(desc->addr & MACB_BIT(RX_USED)))
break;
+ /* Ensure ctrl is at least as up-to-date as addr */
+ dma_rmb();
+
+ ctrl = desc->ctrl;
+
if (ctrl & MACB_BIT(RX_SOF)) {
if (first_frag != -1)
discard_partial_frame(queue, first_frag, tail);
diff --git a/drivers/net/ethernet/cadence/macb_ptp.c b/drivers/net/ethernet/cadence/macb_ptp.c
index cd5296b8..a6dc47e 100644
--- a/drivers/net/ethernet/cadence/macb_ptp.c
+++ b/drivers/net/ethernet/cadence/macb_ptp.c
@@ -319,6 +319,8 @@ int gem_ptp_txstamp(struct macb_queue *queue, struct sk_buff *skb,
desc_ptp = macb_ptp_desc(queue->bp, desc);
tx_timestamp = &queue->tx_timestamps[head];
tx_timestamp->skb = skb;
+ /* ensure ts_1/ts_2 is loaded after ctrl (TX_USED check) */
+ dma_rmb();
tx_timestamp->desc_ptp.ts_1 = desc_ptp->ts_1;
tx_timestamp->desc_ptp.ts_2 = desc_ptp->ts_2;
/* move head */