From: Dmitriy Vyukov <dvyu...@google.com>
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 <dvyu...@google.com>
Tested-by: Aaron Brown <aaron.f.br...@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirs...@intel.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(-)
diff --git a/drivers/net/ethernet/intel/e1000/e1000.h
b/drivers/net/ethernet/intel/e1000/e1000.h
index 6970710..98fe5a2 100644
--- a/drivers/net/ethernet/intel/e1000/e1000.h
+++ b/drivers/net/ethernet/intel/e1000/e1000.h
@@ -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]))
diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c
b/drivers/net/ethernet/intel/e1000/e1000_main.c
index fd7be86..0680235 100644
--- a/drivers/net/ethernet/intel/e1000/e1000_main.c
+++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
@@ -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);
--
2.5.0
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