@@ -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]))
@@ -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);
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> --- drivers/net/ethernet/intel/e1000/e1000.h | 7 +++++-- drivers/net/ethernet/intel/e1000/e1000_main.c | 5 ++++- 2 files changed, 9 insertions(+), 3 deletions(-)