Commit a9d6d897 authored by David S. Miller's avatar David S. Miller
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
parents e2c4cf7f 6e0af298

drivers/net/ethernet/cadence/macb_main.c

+22 −5
Original line number Diff line number Diff line
@@ -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);

drivers/net/ethernet/cadence/macb_ptp.c

+2 −0
Original line number Diff line number Diff line
@@ -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 */

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