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Commit 9eab46b7 authored Sep 08, 2015 by Dmitriy Vyukov Committed by Jeff Kirsher Dec 12, 2015

e1000: fix data race between tx_ring->next_to_clean



e1000_clean_tx_irq cleans buffers and sets tx_ring->next_to_clean,
then e1000_xmit_frame reuses the cleaned buffers. But there are no
memory barriers when buffers gets recycled, so the recycled buffers
can be corrupted.

Use smp_store_release to update tx_ring->next_to_clean and
smp_load_acquire to read tx_ring->next_to_clean to properly
hand off buffers from e1000_clean_tx_irq to e1000_xmit_frame.

The data race was found with KernelThreadSanitizer (KTSAN).

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

parent 18f7ce54

drivers/net/ethernet/intel/e1000/e1000.h

+5 −2

Original line number	Diff line number	Diff line
		@@ -213,8 +213,11 @@ struct e1000_rx_ring {
		};

		#define E1000_DESC_UNUSED(R) \
		((((R)->next_to_clean > (R)->next_to_use) \
		? 0 : (R)->count) + (R)->next_to_clean - (R)->next_to_use - 1)
		({ \
		unsigned int clean = smp_load_acquire(&(R)->next_to_clean); \
		unsigned int use = READ_ONCE((R)->next_to_use); \
		(clean > use ? 0 : (R)->count) + clean - use - 1; \
		})

		#define E1000_RX_DESC_EXT(R, i) \
		(&(((union e1000_rx_desc_extended *)((R).desc))[i]))

drivers/net/ethernet/intel/e1000/e1000_main.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -3876,7 +3876,10 @@ static bool e1000_clean_tx_irq(struct e1000_adapter *adapter,
		eop_desc = E1000_TX_DESC(*tx_ring, eop);
		}

		tx_ring->next_to_clean = i;
		/* Synchronize with E1000_DESC_UNUSED called from e1000_xmit_frame,
		* which will reuse the cleaned buffers.
		*/
		smp_store_release(&tx_ring->next_to_clean, i);

		netdev_completed_queue(netdev, pkts_compl, bytes_compl);