Re: [PATCH V2 2/2] bnx2x: Fix kernel crash and data miscompare after EEH recovery

Quoting Dmitry Kravkov [off-list ref]:

quoted

-----Original Message-----
From: netdev-owner@vger.kernel.org [mailto:netdev-
owner@vger.kernel.org] On Behalf Of wenxiong@linux.vnet.ibm.com
Sent: Wednesday, May 28, 2014 6:57 PM
To: David Miller
Cc: Ariel Elior; netdev; Milton Miller; Wen Xiong
Subject: [PATCH V2 2/2] bnx2x: Fix kernel crash and data miscompare after
EEH recovery

A rmb() is required to ensure that the CQE is not read before it is  
written by
the adapter DMA.  PCI ordering rules will make sure the other fields are
written before the marker at the end of struct eth_fast_path_rx_cqe but
without rmb() a weakly ordered processor can process stale data.

Without the barrier we have observed various crashes including
bnx2x_tpa_start being called on queues not stopped (resulting in message
start of bin not in stop) and NULL pointer exceptions from bnx2x_rx_int.

Signed-off-by: Milton Miller <redacted>
Signed-off-by: Wen Xiong <redacted>
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

Index: b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
===================================================================

--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c 2014-05-23

10:34:21.000000000 -0500

+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c 2014-05-28

10:54:26.627766086 -0500

@@ -906,6 +906,18 @@ static int bnx2x_rx_int(struct bnx2x_fas
              bd_prod = RX_BD(bd_prod);
              bd_cons = RX_BD(bd_cons);

+             /* A rmb() is required to ensure that the CQE is not read
+              * before it is written by the adapter DMA.  PCI ordering
+              * rules will make sure the other fields are written before
+              * the marker at the end of struct eth_fast_path_rx_cqe
+              * but without rmb() a weakly ordered processor can process
+              * stale data.  Without the barrier TPA state-machine might
+              * enter inconsistent state and kernel stack might be
+              * provided with incorrect packet description - these lead
+              * to various kernel crashed.
+             */
+             rmb();
+
              cqe_fp_flags = cqe_fp->type_error_flags;
              cqe_fp_type = cqe_fp_flags &

ETH_FAST_PATH_RX_CQE_TYPE;

The subject states 'EEH recovery', but looks like this is not the  
only case. Other than that:

Acked-by: Dmitry Kravkov <redacted>

Hi Dmitry,

Can you check if you have any comments for 1/2 patch in this series?  
If you don't, can you ack the 1/2 patch as well?

Thanks,
Wendy

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