From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5292C2D0E2 for ; Tue, 22 Sep 2020 11:04:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EAEB20739 for ; Tue, 22 Sep 2020 11:04:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="m8+pDRT1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726588AbgIVLE5 (ORCPT ); Tue, 22 Sep 2020 07:04:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726340AbgIVLE4 (ORCPT ); Tue, 22 Sep 2020 07:04:56 -0400 Received: from mail-ed1-x542.google.com (mail-ed1-x542.google.com [IPv6:2a00:1450:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61776C061755 for ; Tue, 22 Sep 2020 04:04:56 -0700 (PDT) Received: by mail-ed1-x542.google.com with SMTP id j2so15723524eds.9 for ; Tue, 22 Sep 2020 04:04:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Iljx3hlznfUOlzZFRWHMoIF312p8EqGvnsICc6+uq4s=; b=m8+pDRT1UYR17DvhL1oirMw7xuK2AaE3Duy8o3mYCTGXGo+hWktKxaNFygKcib58xt lM6e184mT5WjUic8yOwR/kh8kaQva0jFZEx1K9phgU9Qfcc6yAEeHtIrYSCpE+TJrQ7X A5mE/rsenA4m2mPQgGUU+ykitXKFlMl9/y7N9/bHiNe6ZLKu581Ev/rFN+mTPU1vU5Ed m8BuOXol0MX2UGJiUUAAqcOkdoEqTrJhO0XyEBa/H8J4e8669gmgd4n2cUhvjCKUbBhq IoB/hkmVATWCfze6SLEOm4KlNwSKCGsv2tF/S+v7cO8CWQGDUgk1k4i/34OCA7fGObNN DlVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Iljx3hlznfUOlzZFRWHMoIF312p8EqGvnsICc6+uq4s=; b=KIQX8fd4JFQmGpUQaHi9+XEkKRkRe81YgVHv04GJ+c1FDdYorMasJRvJerK+ozuBFJ k/EBCS2J/nIQR+83SZ2xn/Mv7GnWZXpFt12lld4+xfSW81xOzIIxriC+aUzJqJwiMEva VNJHa4zf9dSViIifgG64Y7+BRJrhdJCVip5Gs7ewGZcbHJNfE6tfVdBqHWjjbj9nfiGu FPRMRg93btHdKGN/sM5l0vteVwqitfBnEA+Jxl+lJ/OQR+nGoY7MgyzyCDNCQjlmb9Zp BI0qz8CWbD0Lz1jPcenq08Qs+MnZG8dwWXh+cE0Rn28v7jerKCr1TsR2EirP57YumHqL eQlQ== X-Gm-Message-State: AOAM531OVlwOX+4ps30+mz7AdTAv0mTys0Y24Tr9GNSBmF9Xn+0zteSv 8EtiRudPKMEZCautJU27CVnAFJ7u4A9+qdgP33pF9Q== X-Google-Smtp-Source: ABdhPJyoZ4shyg8YdvTRpdsw/qs9lya3crCPGnKu9PlTtwPsmdvsPOUphYbLFewzZICDSB9Bh6xuKNXVYdh3v30qi5o= X-Received: by 2002:aa7:c6cf:: with SMTP id b15mr3372034eds.134.1600772694574; Tue, 22 Sep 2020 04:04:54 -0700 (PDT) MIME-Version: 1.0 References: <1600286167-4432-1-git-send-email-hemantk@codeaurora.org> <1600286167-4432-5-git-send-email-hemantk@codeaurora.org> In-Reply-To: <1600286167-4432-5-git-send-email-hemantk@codeaurora.org> From: Loic Poulain Date: Tue, 22 Sep 2020 13:10:07 +0200 Message-ID: Subject: Re: [PATCH v6 4/4] bus: mhi: Add userspace client interface driver To: Hemant Kumar Cc: Manivannan Sadhasivam , Greg Kroah-Hartman , linux-arm-msm , open list , jhugo@codeaurora.org, bbhatt@codeaurora.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Hemant, See comments inline, but globally, the locking and ref counting is more complicated than it should be. On Wed, 16 Sep 2020 at 21:57, Hemant Kumar wrote: > > This MHI client driver allows userspace clients to transfer > raw data between MHI device and host using standard file operations. > Device file node is created with format > > /dev/mhi__ > > Currently it supports LOOPBACK channel. > > Signed-off-by: Hemant Kumar > --- > drivers/bus/mhi/Kconfig | 13 + > drivers/bus/mhi/Makefile | 4 + > drivers/bus/mhi/uci.c | 657 +++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 674 insertions(+) > create mode 100644 drivers/bus/mhi/uci.c > > diff --git a/drivers/bus/mhi/Kconfig b/drivers/bus/mhi/Kconfig > index 6a217ff..8aebe8b 100644 > --- a/drivers/bus/mhi/Kconfig > +++ b/drivers/bus/mhi/Kconfig > @@ -20,3 +20,16 @@ config MHI_BUS_DEBUG > Enable debugfs support for use with the MHI transport. Allows > reading and/or modifying some values within the MHI controller > for debug and test purposes. > + > +config MHI_UCI > + tristate "MHI UCI" > + depends on MHI_BUS > + help > + MHI based userspace client interface driver is used for transferring > + raw data between host and device using standard file operations from > + userspace. Open, read, write, and close operations are supported > + by this driver. Please check mhi_uci_match_table for all supported > + channels that are exposed to userspace. > + > + To compile this driver as a module, choose M here: the module will be > + called mhi_uci. > diff --git a/drivers/bus/mhi/Makefile b/drivers/bus/mhi/Makefile > index 19e6443..80feefb 100644 > --- a/drivers/bus/mhi/Makefile > +++ b/drivers/bus/mhi/Makefile > @@ -1,2 +1,6 @@ > # core layer > obj-y += core/ > + > +# MHI client > +mhi_uci-y := uci.o > +obj-$(CONFIG_MHI_UCI) += mhi_uci.o > diff --git a/drivers/bus/mhi/uci.c b/drivers/bus/mhi/uci.c > new file mode 100644 > index 0000000..d6758f2 > --- /dev/null > +++ b/drivers/bus/mhi/uci.c > @@ -0,0 +1,657 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.*/ > + > +#include > +#include > +#include > +#include > +#include > + > +#define DEVICE_NAME "mhi" > +#define MHI_UCI_DRIVER_NAME "mhi_uci" > +#define MAX_UCI_MINORS (128) > + > +static DEFINE_IDR(uci_idr); > +static DEFINE_MUTEX(uci_idr_mutex); > +static struct class *uci_dev_class; > +static int uci_dev_major; > + > +/** > + * struct uci_chan - MHI channel for a uci device > + * @wq: wait queue for reader/writer > + * @lock: spin lock > + * @pending: list of rx buffers userspace is waiting to read > + * @cur_buf: current buffer userspace is reading > + * @rx_size: size of the current rx buffer userspace is reading > + */ > +struct uci_chan { > + wait_queue_head_t wq; > + > + /* protects pending and cur_buf members in bh context */ > + spinlock_t lock; > + > + struct list_head pending; > + struct uci_buf *cur_buf; > + size_t rx_size; > +}; > + > +/** > + * struct uci_buf - uci buffer > + * @data: data buffer > + * @len: length of data buffer > + * @node: list node of the uci buffer > + */ > +struct uci_buf { > + void *data; > + size_t len; > + struct list_head node; > +}; > + > +/** > + * struct uci_dev - MHI uci device > + * @minor: uci device node minor number > + * @mhi_dev: associated mhi device object > + * @chan: MHI channel name > + * @lock: mutex lock > + * @ul_chan: uplink uci channel object > + * @dl_chan: downlink uci channel object > + * @mtu: max tx buffer length > + * @actual_mtu: maximum size of incoming buffer > + * @open: open called for device node > + * @enabled: uci device probed > + * @ref_count: uci_dev reference count > + */ > +struct uci_dev { > + unsigned int minor; > + struct mhi_device *mhi_dev; > + const char *chan; > + > + /* protects uci_dev struct members */ > + struct mutex lock; > + > + struct uci_chan ul_chan; > + struct uci_chan dl_chan; > + size_t mtu; > + size_t actual_mtu; > + bool enabled; > + struct kref ref_count; > +}; > + > +static int mhi_queue_inbound(struct uci_dev *udev) > +{ > + struct mhi_device *mhi_dev = udev->mhi_dev; > + struct device *dev = &mhi_dev->dev; > + size_t mtu = udev->mtu; > + size_t actual_mtu = udev->actual_mtu; > + int nr_trbs, i, ret = -EIO; > + void *buf; > + struct uci_buf *uci_buf; > + > + nr_trbs = mhi_get_no_free_descriptors(mhi_dev, DMA_FROM_DEVICE); > + > + for (i = 0; i < nr_trbs; i++) { > + buf = kmalloc(mtu, GFP_KERNEL); > + if (!buf) > + return -ENOMEM; > + > + uci_buf = buf + actual_mtu; > + uci_buf->data = buf; > + > + dev_dbg(dev, "Allocated buf %d of %d size %ld\n", i, nr_trbs, > + actual_mtu); > + > + ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, buf, actual_mtu, > + MHI_EOT); > + if (ret) { > + kfree(buf); > + dev_err(dev, "Failed to queue buffer %d\n", i); > + return ret; > + } > + } > + > + return ret; > +} > + > +static void mhi_uci_dev_release(struct kref *ref) > +{ > + struct uci_dev *udev = > + container_of(ref, struct uci_dev, ref_count); > + > + mutex_destroy(&udev->lock); > + > + dev_set_drvdata(&udev->mhi_dev->dev, NULL); > + > + kfree(udev); > +} > + > +static int mhi_uci_release(struct inode *inode, struct file *file) > +{ > + struct uci_dev *udev = file->private_data; > + struct uci_buf *itr, *tmp; > + struct uci_chan *uchan; > + > + if (kref_read(&udev->ref_count) > 2) > + goto exit_uci_release; > + > + if (udev->enabled) > + mhi_unprepare_from_transfer(udev->mhi_dev); > + > + /* clean inbound channel */ > + uchan = &udev->dl_chan; > + > + spin_lock_bh(&uchan->lock); > + list_for_each_entry_safe(itr, tmp, &uchan->pending, node) { > + list_del(&itr->node); > + kfree(itr->data); > + } > + > + if (uchan->cur_buf) > + kfree(uchan->cur_buf->data); > + > + uchan->cur_buf = NULL; > + spin_unlock_bh(&uchan->lock); > + > +exit_uci_release: > + kref_put(&udev->ref_count, mhi_uci_dev_release); > + > + return 0; > +} > + > +static __poll_t mhi_uci_poll(struct file *file, poll_table *wait) > +{ > + struct uci_dev *udev = file->private_data; > + struct mhi_device *mhi_dev = udev->mhi_dev; > + struct device *dev = &mhi_dev->dev; > + struct uci_chan *uchan; > + __poll_t mask = 0; > + > + poll_wait(file, &udev->dl_chan.wq, wait); > + poll_wait(file, &udev->ul_chan.wq, wait); > + > + if (!udev->enabled) { > + mask = EPOLLERR; > + } else { > + uchan = &udev->dl_chan; > + spin_lock_bh(&uchan->lock); > + if (!list_empty(&uchan->pending) || uchan->cur_buf) { > + dev_dbg(dev, "Client can read from node\n"); > + mask |= EPOLLIN | EPOLLRDNORM; > + } > + spin_unlock_bh(&uchan->lock); > + } > + > + if (!udev->enabled) { > + mask |= EPOLLERR; > + } else if (mhi_get_no_free_descriptors(mhi_dev, DMA_TO_DEVICE) > 0) { > + dev_dbg(dev, "Client can write to node\n"); > + mask |= EPOLLOUT | EPOLLWRNORM; > + } > + > + dev_dbg(dev, "Client attempted to poll, returning mask 0x%x\n", mask); > + > + return mask; > +} > + > +static ssize_t mhi_uci_write(struct file *file, > + const char __user *buf, > + size_t count, > + loff_t *offp) > +{ > + struct uci_dev *udev = file->private_data; > + struct mhi_device *mhi_dev = udev->mhi_dev; > + struct device *dev = &mhi_dev->dev; > + struct uci_chan *uchan = &udev->ul_chan; > + size_t bytes_xfered = 0; > + int ret, nr_avail = 0; > + > + if (!buf || !count) > + return -EINVAL; > + > + /* confirm channel is active */ > + mutex_lock(&udev->lock); > + if (!udev->enabled) { > + ret = -ENODEV; > + goto err_mtx_unlock; > + } > + > + dev_dbg(dev, "%s: to xfer: %lu bytes\n", __func__, count); > + > + while (count) { > + size_t xfer_size; > + void *kbuf; > + enum mhi_flags flags; > + > + mutex_unlock(&udev->lock); > + /* wait for free descriptors */ > + ret = wait_event_interruptible(uchan->wq, > + (!udev->enabled) || > + (nr_avail = mhi_get_no_free_descriptors(mhi_dev, > + DMA_TO_DEVICE)) > 0); > + > + mutex_lock(&udev->lock); All this locking unlocking is odd: - why do you need locking for testing wait_event return code? - why do you need this udev->enabled? - The MHI core should be thread safe + mhi_queue_buf should simply fail if removing is ongoing. > + if (ret == -ERESTARTSYS) { > + dev_dbg(dev, "Exit signal caught for node\n"); > + goto err_mtx_unlock; > + } > + > + if (!udev->enabled) { > + ret = -ENODEV; > + goto err_mtx_unlock; > + } > + > + xfer_size = min_t(size_t, count, udev->mtu); > + kbuf = kmalloc(xfer_size, GFP_KERNEL); > + if (!kbuf) { > + ret = -ENOMEM; > + goto err_mtx_unlock; > + } > + > + ret = copy_from_user(kbuf, buf, xfer_size); > + if (ret) { > + kfree(kbuf); > + ret = -EFAULT; > + goto err_mtx_unlock; > + } > + > + /* if ring is full after this force EOT */ > + if (nr_avail > 1 && (count - xfer_size)) > + flags = MHI_CHAIN; > + else > + flags = MHI_EOT; > + > + if (udev->enabled) > + ret = mhi_queue_buf(mhi_dev, DMA_TO_DEVICE, kbuf, > + xfer_size, flags); > + else > + ret = -ENODEV; > + > + if (ret) { > + kfree(kbuf); > + goto err_mtx_unlock; > + } > + > + bytes_xfered += xfer_size; > + count -= xfer_size; > + buf += xfer_size; > + } > + > + mutex_unlock(&udev->lock); > + dev_dbg(dev, "%s: bytes xferred: %lu\n", __func__, bytes_xfered); > + > + return bytes_xfered; > + > +err_mtx_unlock: > + mutex_unlock(&udev->lock); > + > + return ret; > +} > + > +static ssize_t mhi_uci_read(struct file *file, > + char __user *buf, > + size_t count, > + loff_t *ppos) > +{ > + struct uci_dev *udev = file->private_data; > + struct mhi_device *mhi_dev = udev->mhi_dev; > + struct uci_chan *uchan = &udev->dl_chan; > + struct device *dev = &mhi_dev->dev; > + struct uci_buf *ubuf; > + char *ptr; > + size_t to_copy; > + int ret = 0; > + > + if (!buf) > + return -EINVAL; > + > + mutex_lock(&udev->lock); > + /* confirm channel is active */ > + if (!udev->enabled) { > + ret = -ENODEV; > + goto err_mtx_unlock; > + } > + > + spin_lock_bh(&uchan->lock); > + /* No data available to read, wait */ > + if (!uchan->cur_buf && list_empty(&uchan->pending)) { > + dev_dbg(dev, "No data available to read waiting\n"); > + > + spin_unlock_bh(&uchan->lock); > + mutex_unlock(&udev->lock); > + ret = wait_event_interruptible(uchan->wq, > + (!udev->enabled || > + !list_empty(&uchan->pending))); > + > + mutex_lock(&udev->lock); > + if (ret == -ERESTARTSYS) { > + dev_dbg(dev, "Exit signal caught for node\n"); > + goto err_mtx_unlock; > + } > + > + if (!udev->enabled) { > + ret = -ENODEV; > + goto err_mtx_unlock; > + } > + spin_lock_bh(&uchan->lock); > + } > + > + /* new read, get the next descriptor from the list */ > + if (!uchan->cur_buf) { > + ubuf = list_first_entry_or_null(&uchan->pending, > + struct uci_buf, node); > + if (!ubuf) { > + ret = -EIO; > + goto err_spin_unlock; > + } > + > + list_del(&ubuf->node); > + uchan->cur_buf = ubuf; > + uchan->rx_size = ubuf->len; > + dev_dbg(dev, "Got pkt of size: %zu\n", uchan->rx_size); > + } > + > + ubuf = uchan->cur_buf; > + > + /* Copy the buffer to user space */ > + to_copy = min_t(size_t, count, uchan->rx_size); > + ptr = ubuf->data + (ubuf->len - uchan->rx_size); > + spin_unlock_bh(&uchan->lock); > + > + ret = copy_to_user(buf, ptr, to_copy); > + if (ret) { > + ret = -EFAULT; > + goto err_mtx_unlock; > + } > + > + spin_lock_bh(&uchan->lock); > + > + dev_dbg(dev, "Copied %lu of %lu bytes\n", to_copy, uchan->rx_size); > + uchan->rx_size -= to_copy; > + > + /* we finished with this buffer, queue it back to hardware */ > + if (!uchan->rx_size) { > + uchan->cur_buf = NULL; > + > + if (udev->enabled) > + ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, > + ubuf->data, > + udev->actual_mtu, MHI_EOT); > + else > + ret = -ENODEV; > + > + if (ret) { > + dev_err(dev, "Failed to recycle element: %d\n", ret); > + kfree(ubuf->data); > + goto err_spin_unlock; > + } > + } > + spin_unlock_bh(&uchan->lock); > + mutex_unlock(&udev->lock); > + > + dev_dbg(dev, "%s: Returning %lu bytes\n", __func__, to_copy); > + > + return to_copy; > + > +err_spin_unlock: > + spin_unlock_bh(&uchan->lock); > +err_mtx_unlock: > + mutex_unlock(&udev->lock); > + return ret; > +} > + > +static int mhi_uci_open(struct inode *inode, struct file *filp) > +{ > + struct uci_dev *udev = NULL; > + unsigned int minor = iminor(inode); > + int ret = -EIO; > + struct uci_buf *buf_itr, *tmp; > + struct uci_chan *dl_chan; > + struct mhi_device *mhi_dev; > + struct device *dev; > + > + mutex_lock(&uci_idr_mutex); > + udev = idr_find(&uci_idr, minor); > + mutex_unlock(&uci_idr_mutex); > + if (!udev) { > + pr_err("uci dev: minor %d not found\n", minor); > + ret = -ENODEV; > + goto error_no_dev; > + } > + > + kref_get(&udev->ref_count); > + > + mhi_dev = udev->mhi_dev; > + dev = &mhi_dev->dev; > + > + mutex_lock(&udev->lock); > + if (kref_read(&udev->ref_count) > 2) { > + dev_dbg(dev, "Node already opened\n"); > + goto exit_uci_open; > + } > + > + if (!udev->enabled) { > + dev_info(dev, "Node exists, but is not in active state!\n"); > + goto error_open_chan; > + } > + > + dev_dbg(dev, "Starting channel\n"); > + ret = mhi_prepare_for_transfer(udev->mhi_dev); > + if (ret) { > + dev_err(dev, "Error starting transfer channels\n"); > + goto error_open_chan; > + } > + > + ret = mhi_queue_inbound(udev); > + if (ret) > + goto error_rx_queue; > + > +exit_uci_open: > + filp->private_data = udev; > + mutex_unlock(&udev->lock); > + > + return 0; > + > +error_rx_queue: > + dl_chan = &udev->dl_chan; > + mhi_unprepare_from_transfer(udev->mhi_dev); > + list_for_each_entry_safe(buf_itr, tmp, &dl_chan->pending, node) { > + list_del(&buf_itr->node); > + kfree(buf_itr->data); > + } > +error_open_chan: > + mutex_unlock(&udev->lock); > + kref_put(&udev->ref_count, mhi_uci_dev_release); > +error_no_dev: > + return ret; > +} > + > +static const struct file_operations mhidev_fops = { > + .owner = THIS_MODULE, > + .open = mhi_uci_open, > + .release = mhi_uci_release, > + .read = mhi_uci_read, > + .write = mhi_uci_write, > + .poll = mhi_uci_poll, > +}; > + > +static void mhi_ul_xfer_cb(struct mhi_device *mhi_dev, > + struct mhi_result *mhi_result) > +{ > + struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev); > + struct uci_chan *uchan = &udev->ul_chan; > + struct device *dev = &mhi_dev->dev; > + > + dev_dbg(dev, "status: %d xfer_len: %zu\n", > + mhi_result->transaction_status, mhi_result->bytes_xferd); > + > + kfree(mhi_result->buf_addr); > + > + if (!mhi_result->transaction_status) > + wake_up(&uchan->wq); > +} > + > +static void mhi_dl_xfer_cb(struct mhi_device *mhi_dev, > + struct mhi_result *mhi_result) > +{ > + struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev); > + struct uci_chan *uchan = &udev->dl_chan; > + struct device *dev = &mhi_dev->dev; > + struct uci_buf *buf; > + > + dev_dbg(dev, "status: %d receive_len: %zu\n", > + mhi_result->transaction_status, mhi_result->bytes_xferd); > + > + if (mhi_result->transaction_status == -ENOTCONN) { > + kfree(mhi_result->buf_addr); > + return; > + } > + > + spin_lock_bh(&uchan->lock); > + buf = mhi_result->buf_addr + udev->actual_mtu; > + buf->data = mhi_result->buf_addr; > + buf->len = mhi_result->bytes_xferd; You don't need to protect buf here, only uchan pending list, right? so move lock here. > + list_add_tail(&buf->node, &uchan->pending); > + spin_unlock_bh(&uchan->lock); > + > + wake_up(&uchan->wq); > +} > + > +static int mhi_uci_probe(struct mhi_device *mhi_dev, > + const struct mhi_device_id *id) > +{ > + struct uci_dev *udev; > + struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl; > + struct device *dev; > + int index, dir; > + > + udev = kzalloc(sizeof(*udev), GFP_KERNEL); > + if (!udev) > + return -ENOMEM; > + > + kref_init(&udev->ref_count); > + mutex_init(&udev->lock); > + udev->mhi_dev = mhi_dev; > + > + mutex_lock(&udev->lock); Why locking here? udev has just been created, it cannot be used concurrently. > + > + mutex_lock(&uci_idr_mutex); > + index = idr_alloc(&uci_idr, udev, 0, MAX_UCI_MINORS, GFP_KERNEL); > + mutex_unlock(&uci_idr_mutex); > + if (index < 0) { > + mutex_unlock(&udev->lock); > + kfree(udev); > + return index; > + } > + > + udev->minor = index; > + > + /* create device file node /dev/mhi__ */ > + dev = device_create(uci_dev_class, &mhi_dev->dev, > + MKDEV(uci_dev_major, index), udev, > + DEVICE_NAME "_%s_%s", > + dev_name(mhi_cntrl->cntrl_dev), mhi_dev->name); > + if (IS_ERR(dev)) { > + mutex_lock(&uci_idr_mutex); > + idr_remove(&uci_idr, udev->minor); > + mutex_unlock(&uci_idr_mutex); > + mutex_unlock(&udev->lock); > + kfree(udev); > + return PTR_ERR(dev); > + } I would suggest adding the device at the very end of the probe, when everything has been initialized. Regards, Loic > + > + for (dir = 0; dir < 2; dir++) { > + struct uci_chan *uchan = (dir) ? > + &udev->ul_chan : &udev->dl_chan; > + spin_lock_init(&uchan->lock); > + init_waitqueue_head(&uchan->wq); > + INIT_LIST_HEAD(&uchan->pending); > + } > + > + udev->mtu = min_t(size_t, id->driver_data, MHI_MAX_MTU); > + udev->actual_mtu = udev->mtu - sizeof(struct uci_buf); > + dev_set_drvdata(&mhi_dev->dev, udev); > + udev->enabled = true; > + > + mutex_unlock(&udev->lock); > + > + dev_info(&mhi_dev->dev, "probed uci dev: minor %d\n", index); > + > + return 0; > +}; > + > +static void mhi_uci_remove(struct mhi_device *mhi_dev) > +{ > + struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev); > + > + mutex_lock(&udev->lock); > + > + /* disable the node */ > + udev->enabled = false; > + > + wake_up(&udev->dl_chan.wq); > + wake_up(&udev->ul_chan.wq); > + > + /* delete the node to prevent new opens */ > + device_destroy(uci_dev_class, MKDEV(uci_dev_major, udev->minor)); > + > + mutex_lock(&uci_idr_mutex); > + idr_remove(&uci_idr, udev->minor); > + mutex_unlock(&uci_idr_mutex); > + > + mutex_unlock(&udev->lock); > + > + kref_put(&udev->ref_count, mhi_uci_dev_release); > +} > + > +/* .driver_data stores max mtu */ > +static const struct mhi_device_id mhi_uci_match_table[] = { > + { .chan = "LOOPBACK", .driver_data = 0x1000}, > + {}, > +}; > +MODULE_DEVICE_TABLE(mhi, mhi_uci_match_table); > + > +static struct mhi_driver mhi_uci_driver = { > + .id_table = mhi_uci_match_table, > + .remove = mhi_uci_remove, > + .probe = mhi_uci_probe, > + .ul_xfer_cb = mhi_ul_xfer_cb, > + .dl_xfer_cb = mhi_dl_xfer_cb, > + .driver = { > + .name = MHI_UCI_DRIVER_NAME, > + }, > +}; > + > +static int mhi_uci_init(void) > +{ > + int ret; > + > + ret = register_chrdev(0, MHI_UCI_DRIVER_NAME, &mhidev_fops); > + if (ret < 0) > + return ret; > + > + uci_dev_major = ret; > + uci_dev_class = class_create(THIS_MODULE, MHI_UCI_DRIVER_NAME); > + if (IS_ERR(uci_dev_class)) { > + unregister_chrdev(uci_dev_major, MHI_UCI_DRIVER_NAME); > + return -ENODEV; > + } > + > + ret = mhi_driver_register(&mhi_uci_driver); > + if (ret) { > + class_destroy(uci_dev_class); > + unregister_chrdev(uci_dev_major, MHI_UCI_DRIVER_NAME); > + } > + > + return ret; > +} > + > +static void __exit mhi_uci_exit(void) > +{ > + mhi_driver_unregister(&mhi_uci_driver); > + class_destroy(uci_dev_class); > + unregister_chrdev(uci_dev_major, MHI_UCI_DRIVER_NAME); > +} > + > +module_init(mhi_uci_init); > +module_exit(mhi_uci_exit); > +MODULE_LICENSE("GPL v2"); > +MODULE_DESCRIPTION("MHI UCI Driver"); > -- > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project >