From: Eric Dumazet <eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> To: "jianchao.wang" <jianchao.w.wang-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>, Tariq Toukan <tariqt-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, Jason Gunthorpe <jgg-uk2M96/98Pc@public.gmane.org> Cc: junxiao.bi-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Saeed Mahameed <saeedm-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> Subject: Re: [PATCH] net/mlx4_en: ensure rx_desc updating reaches HW before prod db updating Date: Fri, 19 Jan 2018 07:49:59 -0800 [thread overview] Message-ID: <1516376999.3606.39.camel@gmail.com> (raw) In-Reply-To: <53b1ac4d-a294-eb98-149e-65d7954243da-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> On Fri, 2018-01-19 at 23:16 +0800, jianchao.wang wrote: > Hi Tariq > > Very sad that the crash was reproduced again after applied the patch. > > --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c > +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c > @@ -252,6 +252,7 @@ static inline bool mlx4_en_is_ring_empty(struct mlx4_en_rx_ring *ring) > > static inline void mlx4_en_update_rx_prod_db(struct mlx4_en_rx_ring *ring) > { > + dma_wmb(); So... is wmb() here fixing the issue ? > *ring->wqres.db.db = cpu_to_be32(ring->prod & 0xffff); > } > > I analyzed the kdump, it should be a memory corruption. > > Thanks > Jianchao > On 01/15/2018 01:50 PM, jianchao.wang wrote: > > Hi Tariq > > > > Thanks for your kindly response. > > > > On 01/14/2018 05:47 PM, Tariq Toukan wrote: > > > Thanks Jianchao for your patch. > > > > > > And Thank you guys for your reviews, much appreciated. > > > I was off-work on Friday and Saturday. > > > > > > On 14/01/2018 4:40 AM, jianchao.wang wrote: > > > > Dear all > > > > > > > > Thanks for the kindly response and reviewing. That's really appreciated. > > > > > > > > On 01/13/2018 12:46 AM, Eric Dumazet wrote: > > > > > > Does this need to be dma_wmb(), and should it be in > > > > > > mlx4_en_update_rx_prod_db ? > > > > > > > > > > > > > > > > +1 on dma_wmb() > > > > > > > > > > On what architecture bug was observed ? > > > > > > > > This issue was observed on x86-64. > > > > And I will send a new patch, in which replace wmb() with dma_wmb(), to customer > > > > to confirm. > > > > > > +1 on dma_wmb, let us know once customer confirms. > > > Please place it within mlx4_en_update_rx_prod_db as suggested. > > > > Yes, I have recommended it to customer. > > Once I get the result, I will share it here. > > > All other calls to mlx4_en_update_rx_prod_db are in control/slow path so I prefer being on the safe side, and care less about bulking the barrier. > > > > > > Thanks, > > > Tariq > > > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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From: Eric Dumazet <eric.dumazet@gmail.com> To: "jianchao.wang" <jianchao.w.wang@oracle.com>, Tariq Toukan <tariqt@mellanox.com>, Jason Gunthorpe <jgg@ziepe.ca> Cc: junxiao.bi@oracle.com, netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, Saeed Mahameed <saeedm@mellanox.com> Subject: Re: [PATCH] net/mlx4_en: ensure rx_desc updating reaches HW before prod db updating Date: Fri, 19 Jan 2018 07:49:59 -0800 [thread overview] Message-ID: <1516376999.3606.39.camel@gmail.com> (raw) In-Reply-To: <53b1ac4d-a294-eb98-149e-65d7954243da@oracle.com> On Fri, 2018-01-19 at 23:16 +0800, jianchao.wang wrote: > Hi Tariq > > Very sad that the crash was reproduced again after applied the patch. > > --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c > +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c > @@ -252,6 +252,7 @@ static inline bool mlx4_en_is_ring_empty(struct mlx4_en_rx_ring *ring) > > static inline void mlx4_en_update_rx_prod_db(struct mlx4_en_rx_ring *ring) > { > + dma_wmb(); So... is wmb() here fixing the issue ? > *ring->wqres.db.db = cpu_to_be32(ring->prod & 0xffff); > } > > I analyzed the kdump, it should be a memory corruption. > > Thanks > Jianchao > On 01/15/2018 01:50 PM, jianchao.wang wrote: > > Hi Tariq > > > > Thanks for your kindly response. > > > > On 01/14/2018 05:47 PM, Tariq Toukan wrote: > > > Thanks Jianchao for your patch. > > > > > > And Thank you guys for your reviews, much appreciated. > > > I was off-work on Friday and Saturday. > > > > > > On 14/01/2018 4:40 AM, jianchao.wang wrote: > > > > Dear all > > > > > > > > Thanks for the kindly response and reviewing. That's really appreciated. > > > > > > > > On 01/13/2018 12:46 AM, Eric Dumazet wrote: > > > > > > Does this need to be dma_wmb(), and should it be in > > > > > > mlx4_en_update_rx_prod_db ? > > > > > > > > > > > > > > > > +1 on dma_wmb() > > > > > > > > > > On what architecture bug was observed ? > > > > > > > > This issue was observed on x86-64. > > > > And I will send a new patch, in which replace wmb() with dma_wmb(), to customer > > > > to confirm. > > > > > > +1 on dma_wmb, let us know once customer confirms. > > > Please place it within mlx4_en_update_rx_prod_db as suggested. > > > > Yes, I have recommended it to customer. > > Once I get the result, I will share it here. > > > All other calls to mlx4_en_update_rx_prod_db are in control/slow path so I prefer being on the safe side, and care less about bulking the barrier. > > > > > > Thanks, > > > Tariq > > >
next prev parent reply other threads:[~2018-01-19 15:49 UTC|newest] Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-01-12 3:42 [PATCH] net/mlx4_en: ensure rx_desc updating reaches HW before prod db updating Jianchao Wang 2018-01-12 3:42 ` Jianchao Wang 2018-01-12 16:32 ` Jason Gunthorpe [not found] ` <20180112163247.GB15974-uk2M96/98Pc@public.gmane.org> 2018-01-12 16:46 ` Eric Dumazet 2018-01-12 16:46 ` Eric Dumazet 2018-01-12 19:53 ` Saeed Mahameed [not found] ` <85116e56-52b1-944d-6ee2-916ccfc3a7a6-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> 2018-01-12 20:16 ` Eric Dumazet 2018-01-12 20:16 ` Eric Dumazet 2018-01-12 21:01 ` Saeed Mahameed 2018-01-12 21:21 ` Eric Dumazet [not found] ` <e902138a-3508-3504-51e5-46152cc2fb31-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> 2018-01-13 19:15 ` Jason Gunthorpe 2018-01-13 19:15 ` Jason Gunthorpe 2018-01-14 2:40 ` jianchao.wang [not found] ` <a40e44f4-106b-1075-8f92-f7741508372c-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> 2018-01-14 9:47 ` Tariq Toukan 2018-01-14 9:47 ` Tariq Toukan 2018-01-15 5:50 ` jianchao.wang [not found] ` <fea0aa1c-b68e-9485-3826-2dfad7824911-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> 2018-01-19 15:16 ` jianchao.wang 2018-01-19 15:16 ` jianchao.wang [not found] ` <53b1ac4d-a294-eb98-149e-65d7954243da-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> 2018-01-19 15:49 ` Eric Dumazet [this message] 2018-01-19 15:49 ` Eric Dumazet 2018-01-21 9:31 ` Tariq Toukan [not found] ` <dfc02a48-7d2a-56da-dc4e-d90a9fcc559c-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> 2018-01-21 16:24 ` Tariq Toukan 2018-01-21 16:24 ` Tariq Toukan 2018-01-21 16:43 ` Eric Dumazet [not found] ` <1516552998.3478.5.camel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2018-01-22 2:40 ` jianchao.wang 2018-01-22 2:40 ` jianchao.wang 2018-01-22 15:47 ` Jason Gunthorpe 2018-01-23 3:25 ` jianchao.wang 2018-01-22 2:12 ` jianchao.wang [not found] ` <c8b0955b-a3fc-afe2-2c67-e655ca2ee6f6-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> 2018-01-25 3:27 ` jianchao.wang 2018-01-25 3:27 ` jianchao.wang [not found] ` <532b4d71-e2eb-35f3-894e-1c3288e7bc3f-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> 2018-01-25 3:55 ` Eric Dumazet 2018-01-25 3:55 ` Eric Dumazet [not found] ` <1516852543.3715.43.camel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2018-01-25 6:25 ` jianchao.wang 2018-01-25 6:25 ` jianchao.wang [not found] ` <89066a75-43db-0f62-f171-70b0abaa8ea0-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> 2018-01-25 9:54 ` Tariq Toukan 2018-01-25 9:54 ` Tariq Toukan [not found] ` <918db4ec-8c3c-aafa-4be6-0e00a99632e2-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> 2018-01-27 12:41 ` jianchao.wang 2018-01-27 12:41 ` jianchao.wang [not found] ` <d9883261-e93e-400a-757c-3a81d8b6aca1@mellanox.com> 2019-01-02 1:43 ` jianchao.wang 2018-01-21 20:40 ` Jason Gunthorpe
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