From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH for-next 03/10] IB/iser: Don't register memory for all immediatedata writes Date: Tue, 17 Nov 2015 11:41:39 +0200 Message-ID: <564AF653.6060401@dev.mellanox.co.il> References: <1447691861-3796-1-git-send-email-sagig@mellanox.com> <1447691861-3796-4-git-send-email-sagig@mellanox.com> <564ADB7D.20806@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <564ADB7D.20806-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Or Gerlitz , Sagi Grimberg , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, target-devel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: "Nicholas A. Bellinger" , Steve Wise , Jenny Derzhavetz List-Id: linux-rdma@vger.kernel.org > On 11/16/2015 6:37 PM, Sagi Grimberg wrote: >> --- a/drivers/infiniband/ulp/iser/iser_memory.c >> +++ b/drivers/infiniband/ulp/iser/iser_memory.c >> @@ -250,7 +250,7 @@ iser_reg_dma(struct iser_device *device, struct >> iser_data_buf *mem, >> struct scatterlist *sg = mem->sg; >> reg->sge.lkey = device->pd->local_dma_lkey; >> - reg->rkey = device->mr->rkey; >> + reg->rkey = device->mr ? device->mr->rkey : 0; >> reg->sge.addr = ib_sg_dma_address(device->ib_device, &sg[0]); >> reg->sge.length = ib_sg_dma_len(device->ib_device, &sg[0]); > > what's the role of this hunk? why it belongs here? you are testing > device->mr but this is > something global and has nothing to do specially with specific IOs for > which this patch > aims to act It's because device->mr might not be allocated at all if always_register=Y, however in this case for all-immediatedata writes I don't need memory registration and I can use pd->local_dma_lkey. This hunk prevents a NULL dereference (as I mentioned, device->mr might not be allocated at all). -- 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