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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id q61sm3039205pja.2.2020.03.24.13.39.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2020 13:39:55 -0700 (PDT) Date: Tue, 24 Mar 2020 13:39:52 -0700 From: Bjorn Andersson To: Manivannan Sadhasivam Cc: gregkh@linuxfoundation.org, davem@davemloft.net, smohanad@codeaurora.org, jhugo@codeaurora.org, kvalo@codeaurora.org, hemantk@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH v3 6/7] net: qrtr: Add MHI transport layer Message-ID: <20200324203952.GC119913@minitux> References: <20200324061050.14845-1-manivannan.sadhasivam@linaro.org> <20200324061050.14845-7-manivannan.sadhasivam@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200324061050.14845-7-manivannan.sadhasivam@linaro.org> Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Mon 23 Mar 23:10 PDT 2020, Manivannan Sadhasivam wrote: > MHI is the transport layer used for communicating to the external modems. > Hence, this commit adds MHI transport layer support to QRTR for > transferring the QMI messages over IPC Router. > > Cc: "David S. Miller" > Cc: netdev@vger.kernel.org > Signed-off-by: Manivannan Sadhasivam > --- > net/qrtr/Kconfig | 7 ++ > net/qrtr/Makefile | 2 + > net/qrtr/mhi.c | 208 ++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 217 insertions(+) > create mode 100644 net/qrtr/mhi.c > > diff --git a/net/qrtr/Kconfig b/net/qrtr/Kconfig > index 63f89cc6e82c..8eb876471564 100644 > --- a/net/qrtr/Kconfig > +++ b/net/qrtr/Kconfig > @@ -29,4 +29,11 @@ config QRTR_TUN > implement endpoints of QRTR, for purpose of tunneling data to other > hosts or testing purposes. > > +config QRTR_MHI > + tristate "MHI IPC Router channels" > + depends on MHI_BUS > + help > + Say Y here to support MHI based ipcrouter channels. MHI is the > + transport used for communicating to external modems. > + > endif # QRTR > diff --git a/net/qrtr/Makefile b/net/qrtr/Makefile > index 1c6d6c120fb7..3dc0a7c9d455 100644 > --- a/net/qrtr/Makefile > +++ b/net/qrtr/Makefile > @@ -5,3 +5,5 @@ obj-$(CONFIG_QRTR_SMD) += qrtr-smd.o > qrtr-smd-y := smd.o > obj-$(CONFIG_QRTR_TUN) += qrtr-tun.o > qrtr-tun-y := tun.o > +obj-$(CONFIG_QRTR_MHI) += qrtr-mhi.o > +qrtr-mhi-y := mhi.o > diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c > new file mode 100644 > index 000000000000..90af208f34c1 > --- /dev/null > +++ b/net/qrtr/mhi.c > @@ -0,0 +1,208 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved. > + */ > + > +#include > +#include > +#include > +#include > +#include > + > +#include "qrtr.h" > + > +struct qrtr_mhi_dev { > + struct qrtr_endpoint ep; > + struct mhi_device *mhi_dev; > + struct device *dev; > + spinlock_t ul_lock; /* lock to protect ul_pkts */ > + struct list_head ul_pkts; > + atomic_t in_reset; > +}; > + > +struct qrtr_mhi_pkt { > + struct list_head node; > + struct sk_buff *skb; > + struct kref refcount; > + struct completion done; > +}; > + > +static void qrtr_mhi_pkt_release(struct kref *ref) > +{ > + struct qrtr_mhi_pkt *pkt = container_of(ref, struct qrtr_mhi_pkt, > + refcount); > + struct sock *sk = pkt->skb->sk; > + > + consume_skb(pkt->skb); > + if (sk) > + sock_put(sk); > + > + kfree(pkt); > +} > + > +/* From MHI to QRTR */ > +static void qcom_mhi_qrtr_dl_callback(struct mhi_device *mhi_dev, > + struct mhi_result *mhi_res) > +{ > + struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev); > + int rc; > + > + if (!qdev || mhi_res->transaction_status) > + return; > + > + rc = qrtr_endpoint_post(&qdev->ep, mhi_res->buf_addr, > + mhi_res->bytes_xferd); > + if (rc == -EINVAL) > + dev_err(qdev->dev, "invalid ipcrouter packet\n"); Perhaps this should be a debug print, perhaps rate limited. But either way it's relevant for any transport, so I think you should skip it here - and potentially move it into qrtr_endpoint_post() in some form. > +} > + > +/* From QRTR to MHI */ > +static void qcom_mhi_qrtr_ul_callback(struct mhi_device *mhi_dev, > + struct mhi_result *mhi_res) > +{ > + struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev); > + struct qrtr_mhi_pkt *pkt; > + unsigned long flags; > + > + spin_lock_irqsave(&qdev->ul_lock, flags); > + pkt = list_first_entry(&qdev->ul_pkts, struct qrtr_mhi_pkt, node); > + list_del(&pkt->node); > + complete_all(&pkt->done); You should be able to release the lock after popping the item off the list, then complete and refcount it. > + > + kref_put(&pkt->refcount, qrtr_mhi_pkt_release); > + spin_unlock_irqrestore(&qdev->ul_lock, flags); > +} > + > +static void qcom_mhi_qrtr_status_callback(struct mhi_device *mhi_dev, > + enum mhi_callback mhi_cb) > +{ > + struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev); > + struct qrtr_mhi_pkt *pkt; > + unsigned long flags; > + > + if (mhi_cb != MHI_CB_FATAL_ERROR) > + return; > + > + atomic_inc(&qdev->in_reset); You have ul_lock close at hand in both places where you access in_reset, so I think it would be better to just use that, instead of an atomic. > + spin_lock_irqsave(&qdev->ul_lock, flags); > + list_for_each_entry(pkt, &qdev->ul_pkts, node) > + complete_all(&pkt->done); > + spin_unlock_irqrestore(&qdev->ul_lock, flags); > +} > + > +/* Send data over MHI */ > +static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb) > +{ > + struct qrtr_mhi_dev *qdev = container_of(ep, struct qrtr_mhi_dev, ep); > + struct qrtr_mhi_pkt *pkt; > + int rc; > + > + rc = skb_linearize(skb); > + if (rc) { > + kfree_skb(skb); > + return rc; > + } > + > + pkt = kzalloc(sizeof(*pkt), GFP_KERNEL); > + if (!pkt) { > + kfree_skb(skb); > + return -ENOMEM; > + } > + > + init_completion(&pkt->done); > + kref_init(&pkt->refcount); > + kref_get(&pkt->refcount); > + pkt->skb = skb; > + > + spin_lock_bh(&qdev->ul_lock); > + list_add_tail(&pkt->node, &qdev->ul_pkts); > + rc = mhi_queue_skb(qdev->mhi_dev, DMA_TO_DEVICE, skb, skb->len, > + MHI_EOT); Do you want to continue doing this when qdev->in_reset? Wouldn't it be better to bail early if the remote end is dying? > + if (rc) { > + list_del(&pkt->node); > + /* Reference count needs to be dropped 2 times */ > + kref_put(&pkt->refcount, qrtr_mhi_pkt_release); > + kref_put(&pkt->refcount, qrtr_mhi_pkt_release); > + kfree_skb(skb); > + spin_unlock_bh(&qdev->ul_lock); > + return rc; > + } > + > + spin_unlock_bh(&qdev->ul_lock); > + if (skb->sk) > + sock_hold(skb->sk); > + > + rc = wait_for_completion_interruptible_timeout(&pkt->done, HZ * 5); > + if (atomic_read(&qdev->in_reset)) > + rc = -ECONNRESET; > + else if (rc == 0) > + rc = -ETIMEDOUT; Is this recoverable? The message will remain on the list and may be delivered at a later point(?), but qrtr and the app will learn that the message was lost - which is presumably considered fatal. Is it guaranteed that qcom_mhi_qrtr_ul_callback() will happen later and find the head of the list? The reason for my question is that without this you have one of two scenarios; 1) the message is put on the list, decremented in qcom_mhi_qrtr_ul_callback() then we get back here and decrement it again. 2) the message is put on the list, then qcom_mhi_qrtr_status_callback() happens and all messages are released - presumably then qcom_mhi_qrtr_ul_callback() won't happen. So if the third case (where we return here and then later qcom_mhi_qrtr_ul_callback() must find this particular packet at the front of the queue) can't happen, then you can just skip the entire refcounting. Further more, you could carry qrtr_mhi_pkt on the stack. ...or to flip this around, is there a reason to wait here at all? What would happen if you just return immediately after calling mhi_queue_skb()? Wouldn't that provide you better throughput? > + else if (rc > 0) > + rc = 0; > + > + kref_put(&pkt->refcount, qrtr_mhi_pkt_release); > + > + return rc; > +} > + > +static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev, > + const struct mhi_device_id *id) > +{ > + struct qrtr_mhi_dev *qdev; > + u32 net_id; > + int rc; > + > + qdev = devm_kzalloc(&mhi_dev->dev, sizeof(*qdev), GFP_KERNEL); > + if (!qdev) > + return -ENOMEM; > + > + qdev->mhi_dev = mhi_dev; > + qdev->dev = &mhi_dev->dev; > + qdev->ep.xmit = qcom_mhi_qrtr_send; > + atomic_set(&qdev->in_reset, 0); > + > + net_id = QRTR_EP_NID_AUTO; Just pass QRTR_EP_NID_AUTO directly in the function call below. Regards, Bjorn > + > + INIT_LIST_HEAD(&qdev->ul_pkts); > + spin_lock_init(&qdev->ul_lock); > + > + dev_set_drvdata(&mhi_dev->dev, qdev); > + rc = qrtr_endpoint_register(&qdev->ep, net_id); > + if (rc) > + return rc; > + > + dev_dbg(qdev->dev, "Qualcomm MHI QRTR driver probed\n"); > + > + return 0; > +} > + > +static void qcom_mhi_qrtr_remove(struct mhi_device *mhi_dev) > +{ > + struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev); > + > + qrtr_endpoint_unregister(&qdev->ep); > + dev_set_drvdata(&mhi_dev->dev, NULL); > +} > + > +static const struct mhi_device_id qcom_mhi_qrtr_id_table[] = { > + { .chan = "IPCR" }, > + {} > +}; > +MODULE_DEVICE_TABLE(mhi, qcom_mhi_qrtr_id_table); > + > +static struct mhi_driver qcom_mhi_qrtr_driver = { > + .probe = qcom_mhi_qrtr_probe, > + .remove = qcom_mhi_qrtr_remove, > + .dl_xfer_cb = qcom_mhi_qrtr_dl_callback, > + .ul_xfer_cb = qcom_mhi_qrtr_ul_callback, > + .status_cb = qcom_mhi_qrtr_status_callback, > + .id_table = qcom_mhi_qrtr_id_table, > + .driver = { > + .name = "qcom_mhi_qrtr", > + }, > +}; > + > +module_mhi_driver(qcom_mhi_qrtr_driver); > + > +MODULE_DESCRIPTION("Qualcomm IPC-Router MHI interface driver"); > +MODULE_LICENSE("GPL v2"); > -- > 2.17.1 >