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![André Almeida](/assets/img/avatar_default.png)
Currently, the table that stores information about the connected hidraw devices has a mutex to prevent concurrent hidraw users to manipulate the hidraw table (e.g. delete an entry) while someone is trying to use the table (e.g. issuing an ioctl to the device), preventing the kernel to referencing a NULL pointer. However, since that every user that wants to access the table for both manipulating it and reading it content, this prevents concurrent access to the table for read-only operations for different or the same device (e.g. two hidraw ioctls can't happen at the same time, even if they are completely unrelated). This proves to be a bottleneck and gives performance issues when using multiple HID devices at same time, like VR kits where one can have two controllers, the headset and some tracking sensors. To improve the performance, replace the table mutex with a read-write semaphore, enabling multiple threads to issue parallel syscalls to multiple devices at the same time while protecting the table for concurrent modifications. Signed-off-by: André Almeida <andrealmeid@collabora.com> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> Link: https://lore.kernel.org/r/20211130132957.8480-2-andrealmeid@collabora.com
649 lines
14 KiB
C
649 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* HID raw devices, giving access to raw HID events.
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*
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* In comparison to hiddev, this device does not process the
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* hid events at all (no parsing, no lookups). This lets applications
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* to work on raw hid events as they want to, and avoids a need to
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* use a transport-specific userspace libhid/libusb libraries.
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*
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* Copyright (c) 2007-2014 Jiri Kosina
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/cdev.h>
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#include <linux/poll.h>
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#include <linux/device.h>
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#include <linux/major.h>
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#include <linux/slab.h>
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#include <linux/hid.h>
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#include <linux/mutex.h>
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#include <linux/sched/signal.h>
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#include <linux/string.h>
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#include <linux/hidraw.h>
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static int hidraw_major;
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static struct cdev hidraw_cdev;
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static struct class *hidraw_class;
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static struct hidraw *hidraw_table[HIDRAW_MAX_DEVICES];
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static DECLARE_RWSEM(minors_rwsem);
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static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
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{
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struct hidraw_list *list = file->private_data;
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int ret = 0, len;
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DECLARE_WAITQUEUE(wait, current);
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mutex_lock(&list->read_mutex);
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while (ret == 0) {
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if (list->head == list->tail) {
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add_wait_queue(&list->hidraw->wait, &wait);
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set_current_state(TASK_INTERRUPTIBLE);
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while (list->head == list->tail) {
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if (signal_pending(current)) {
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ret = -ERESTARTSYS;
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break;
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}
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if (!list->hidraw->exist) {
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ret = -EIO;
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break;
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}
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if (file->f_flags & O_NONBLOCK) {
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ret = -EAGAIN;
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break;
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}
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/* allow O_NONBLOCK to work well from other threads */
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mutex_unlock(&list->read_mutex);
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schedule();
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mutex_lock(&list->read_mutex);
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set_current_state(TASK_INTERRUPTIBLE);
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}
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set_current_state(TASK_RUNNING);
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remove_wait_queue(&list->hidraw->wait, &wait);
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}
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if (ret)
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goto out;
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len = list->buffer[list->tail].len > count ?
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count : list->buffer[list->tail].len;
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if (list->buffer[list->tail].value) {
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if (copy_to_user(buffer, list->buffer[list->tail].value, len)) {
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ret = -EFAULT;
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goto out;
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}
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ret = len;
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}
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kfree(list->buffer[list->tail].value);
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list->buffer[list->tail].value = NULL;
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list->tail = (list->tail + 1) & (HIDRAW_BUFFER_SIZE - 1);
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}
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out:
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mutex_unlock(&list->read_mutex);
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return ret;
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}
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/*
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* The first byte of the report buffer is expected to be a report number.
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*/
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static ssize_t hidraw_send_report(struct file *file, const char __user *buffer, size_t count, unsigned char report_type)
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{
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unsigned int minor = iminor(file_inode(file));
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struct hid_device *dev;
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__u8 *buf;
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int ret = 0;
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lockdep_assert_held(&minors_rwsem);
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if (!hidraw_table[minor] || !hidraw_table[minor]->exist) {
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ret = -ENODEV;
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goto out;
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}
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dev = hidraw_table[minor]->hid;
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if (count > HID_MAX_BUFFER_SIZE) {
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hid_warn(dev, "pid %d passed too large report\n",
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task_pid_nr(current));
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ret = -EINVAL;
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goto out;
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}
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if (count < 2) {
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hid_warn(dev, "pid %d passed too short report\n",
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task_pid_nr(current));
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ret = -EINVAL;
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goto out;
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}
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buf = memdup_user(buffer, count);
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if (IS_ERR(buf)) {
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ret = PTR_ERR(buf);
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goto out;
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}
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if ((report_type == HID_OUTPUT_REPORT) &&
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!(dev->quirks & HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP)) {
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ret = hid_hw_output_report(dev, buf, count);
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/*
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* compatibility with old implementation of USB-HID and I2C-HID:
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* if the device does not support receiving output reports,
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* on an interrupt endpoint, fallback to SET_REPORT HID command.
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*/
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if (ret != -ENOSYS)
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goto out_free;
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}
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ret = hid_hw_raw_request(dev, buf[0], buf, count, report_type,
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HID_REQ_SET_REPORT);
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out_free:
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kfree(buf);
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out:
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return ret;
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}
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static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
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{
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ssize_t ret;
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down_read(&minors_rwsem);
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ret = hidraw_send_report(file, buffer, count, HID_OUTPUT_REPORT);
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up_read(&minors_rwsem);
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return ret;
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}
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/*
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* This function performs a Get_Report transfer over the control endpoint
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* per section 7.2.1 of the HID specification, version 1.1. The first byte
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* of buffer is the report number to request, or 0x0 if the device does not
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* use numbered reports. The report_type parameter can be HID_FEATURE_REPORT
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* or HID_INPUT_REPORT.
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*/
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static ssize_t hidraw_get_report(struct file *file, char __user *buffer, size_t count, unsigned char report_type)
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{
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unsigned int minor = iminor(file_inode(file));
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struct hid_device *dev;
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__u8 *buf;
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int ret = 0, len;
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unsigned char report_number;
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lockdep_assert_held(&minors_rwsem);
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if (!hidraw_table[minor] || !hidraw_table[minor]->exist) {
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ret = -ENODEV;
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goto out;
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}
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dev = hidraw_table[minor]->hid;
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if (!dev->ll_driver->raw_request) {
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ret = -ENODEV;
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goto out;
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}
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if (count > HID_MAX_BUFFER_SIZE) {
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hid_warn(dev, "pid %d passed too large report\n",
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task_pid_nr(current));
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ret = -EINVAL;
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goto out;
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}
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if (count < 2) {
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hid_warn(dev, "pid %d passed too short report\n",
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task_pid_nr(current));
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ret = -EINVAL;
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goto out;
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}
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buf = kmalloc(count, GFP_KERNEL);
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if (!buf) {
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ret = -ENOMEM;
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goto out;
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}
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/*
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* Read the first byte from the user. This is the report number,
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* which is passed to hid_hw_raw_request().
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*/
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if (copy_from_user(&report_number, buffer, 1)) {
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ret = -EFAULT;
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goto out_free;
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}
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ret = hid_hw_raw_request(dev, report_number, buf, count, report_type,
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HID_REQ_GET_REPORT);
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if (ret < 0)
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goto out_free;
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len = (ret < count) ? ret : count;
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if (copy_to_user(buffer, buf, len)) {
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ret = -EFAULT;
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goto out_free;
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}
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ret = len;
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out_free:
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kfree(buf);
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out:
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return ret;
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}
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static __poll_t hidraw_poll(struct file *file, poll_table *wait)
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{
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struct hidraw_list *list = file->private_data;
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__poll_t mask = EPOLLOUT | EPOLLWRNORM; /* hidraw is always writable */
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poll_wait(file, &list->hidraw->wait, wait);
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if (list->head != list->tail)
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mask |= EPOLLIN | EPOLLRDNORM;
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if (!list->hidraw->exist)
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mask |= EPOLLERR | EPOLLHUP;
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return mask;
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}
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static int hidraw_open(struct inode *inode, struct file *file)
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{
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unsigned int minor = iminor(inode);
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struct hidraw *dev;
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struct hidraw_list *list;
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unsigned long flags;
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int err = 0;
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if (!(list = kzalloc(sizeof(struct hidraw_list), GFP_KERNEL))) {
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err = -ENOMEM;
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goto out;
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}
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down_read(&minors_rwsem);
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if (!hidraw_table[minor] || !hidraw_table[minor]->exist) {
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err = -ENODEV;
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goto out_unlock;
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}
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dev = hidraw_table[minor];
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if (!dev->open++) {
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err = hid_hw_power(dev->hid, PM_HINT_FULLON);
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if (err < 0) {
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dev->open--;
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goto out_unlock;
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}
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err = hid_hw_open(dev->hid);
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if (err < 0) {
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hid_hw_power(dev->hid, PM_HINT_NORMAL);
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dev->open--;
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goto out_unlock;
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}
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}
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list->hidraw = hidraw_table[minor];
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mutex_init(&list->read_mutex);
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spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags);
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list_add_tail(&list->node, &hidraw_table[minor]->list);
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spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags);
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file->private_data = list;
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out_unlock:
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up_read(&minors_rwsem);
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out:
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if (err < 0)
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kfree(list);
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return err;
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}
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static int hidraw_fasync(int fd, struct file *file, int on)
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{
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struct hidraw_list *list = file->private_data;
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return fasync_helper(fd, file, on, &list->fasync);
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}
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static void drop_ref(struct hidraw *hidraw, int exists_bit)
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{
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if (exists_bit) {
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hidraw->exist = 0;
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if (hidraw->open) {
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hid_hw_close(hidraw->hid);
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wake_up_interruptible(&hidraw->wait);
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}
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device_destroy(hidraw_class,
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MKDEV(hidraw_major, hidraw->minor));
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} else {
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--hidraw->open;
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}
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if (!hidraw->open) {
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if (!hidraw->exist) {
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hidraw_table[hidraw->minor] = NULL;
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kfree(hidraw);
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} else {
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/* close device for last reader */
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hid_hw_close(hidraw->hid);
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hid_hw_power(hidraw->hid, PM_HINT_NORMAL);
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}
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}
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}
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static int hidraw_release(struct inode * inode, struct file * file)
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{
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unsigned int minor = iminor(inode);
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struct hidraw_list *list = file->private_data;
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unsigned long flags;
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down_write(&minors_rwsem);
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spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags);
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list_del(&list->node);
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spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags);
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kfree(list);
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drop_ref(hidraw_table[minor], 0);
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up_write(&minors_rwsem);
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return 0;
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}
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static long hidraw_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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struct inode *inode = file_inode(file);
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unsigned int minor = iminor(inode);
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long ret = 0;
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struct hidraw *dev;
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void __user *user_arg = (void __user*) arg;
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down_read(&minors_rwsem);
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dev = hidraw_table[minor];
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if (!dev || !dev->exist) {
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ret = -ENODEV;
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goto out;
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}
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switch (cmd) {
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case HIDIOCGRDESCSIZE:
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if (put_user(dev->hid->rsize, (int __user *)arg))
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ret = -EFAULT;
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break;
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case HIDIOCGRDESC:
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{
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__u32 len;
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if (get_user(len, (int __user *)arg))
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ret = -EFAULT;
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else if (len > HID_MAX_DESCRIPTOR_SIZE - 1)
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ret = -EINVAL;
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else if (copy_to_user(user_arg + offsetof(
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struct hidraw_report_descriptor,
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value[0]),
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dev->hid->rdesc,
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min(dev->hid->rsize, len)))
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ret = -EFAULT;
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break;
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}
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case HIDIOCGRAWINFO:
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{
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struct hidraw_devinfo dinfo;
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dinfo.bustype = dev->hid->bus;
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dinfo.vendor = dev->hid->vendor;
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dinfo.product = dev->hid->product;
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if (copy_to_user(user_arg, &dinfo, sizeof(dinfo)))
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ret = -EFAULT;
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break;
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}
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default:
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{
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struct hid_device *hid = dev->hid;
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if (_IOC_TYPE(cmd) != 'H') {
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ret = -EINVAL;
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break;
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}
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if (_IOC_NR(cmd) == _IOC_NR(HIDIOCSFEATURE(0))) {
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int len = _IOC_SIZE(cmd);
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ret = hidraw_send_report(file, user_arg, len, HID_FEATURE_REPORT);
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break;
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}
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if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGFEATURE(0))) {
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int len = _IOC_SIZE(cmd);
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ret = hidraw_get_report(file, user_arg, len, HID_FEATURE_REPORT);
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break;
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}
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if (_IOC_NR(cmd) == _IOC_NR(HIDIOCSINPUT(0))) {
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int len = _IOC_SIZE(cmd);
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ret = hidraw_send_report(file, user_arg, len, HID_INPUT_REPORT);
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break;
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}
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if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGINPUT(0))) {
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int len = _IOC_SIZE(cmd);
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ret = hidraw_get_report(file, user_arg, len, HID_INPUT_REPORT);
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break;
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}
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if (_IOC_NR(cmd) == _IOC_NR(HIDIOCSOUTPUT(0))) {
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int len = _IOC_SIZE(cmd);
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ret = hidraw_send_report(file, user_arg, len, HID_OUTPUT_REPORT);
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break;
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}
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if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGOUTPUT(0))) {
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int len = _IOC_SIZE(cmd);
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ret = hidraw_get_report(file, user_arg, len, HID_OUTPUT_REPORT);
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break;
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}
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/* Begin Read-only ioctls. */
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if (_IOC_DIR(cmd) != _IOC_READ) {
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ret = -EINVAL;
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break;
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}
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if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGRAWNAME(0))) {
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int len = strlen(hid->name) + 1;
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if (len > _IOC_SIZE(cmd))
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len = _IOC_SIZE(cmd);
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ret = copy_to_user(user_arg, hid->name, len) ?
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-EFAULT : len;
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break;
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}
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if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGRAWPHYS(0))) {
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int len = strlen(hid->phys) + 1;
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if (len > _IOC_SIZE(cmd))
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len = _IOC_SIZE(cmd);
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ret = copy_to_user(user_arg, hid->phys, len) ?
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-EFAULT : len;
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break;
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}
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if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGRAWUNIQ(0))) {
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int len = strlen(hid->uniq) + 1;
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if (len > _IOC_SIZE(cmd))
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len = _IOC_SIZE(cmd);
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ret = copy_to_user(user_arg, hid->uniq, len) ?
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-EFAULT : len;
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break;
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}
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}
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ret = -ENOTTY;
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}
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out:
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up_read(&minors_rwsem);
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return ret;
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}
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static const struct file_operations hidraw_ops = {
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.owner = THIS_MODULE,
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.read = hidraw_read,
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.write = hidraw_write,
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.poll = hidraw_poll,
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.open = hidraw_open,
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.release = hidraw_release,
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.unlocked_ioctl = hidraw_ioctl,
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.fasync = hidraw_fasync,
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.compat_ioctl = compat_ptr_ioctl,
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.llseek = noop_llseek,
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};
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|
int hidraw_report_event(struct hid_device *hid, u8 *data, int len)
|
|
{
|
|
struct hidraw *dev = hid->hidraw;
|
|
struct hidraw_list *list;
|
|
int ret = 0;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&dev->list_lock, flags);
|
|
list_for_each_entry(list, &dev->list, node) {
|
|
int new_head = (list->head + 1) & (HIDRAW_BUFFER_SIZE - 1);
|
|
|
|
if (new_head == list->tail)
|
|
continue;
|
|
|
|
if (!(list->buffer[list->head].value = kmemdup(data, len, GFP_ATOMIC))) {
|
|
ret = -ENOMEM;
|
|
break;
|
|
}
|
|
list->buffer[list->head].len = len;
|
|
list->head = new_head;
|
|
kill_fasync(&list->fasync, SIGIO, POLL_IN);
|
|
}
|
|
spin_unlock_irqrestore(&dev->list_lock, flags);
|
|
|
|
wake_up_interruptible(&dev->wait);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(hidraw_report_event);
|
|
|
|
int hidraw_connect(struct hid_device *hid)
|
|
{
|
|
int minor, result;
|
|
struct hidraw *dev;
|
|
|
|
/* we accept any HID device, all applications */
|
|
|
|
dev = kzalloc(sizeof(struct hidraw), GFP_KERNEL);
|
|
if (!dev)
|
|
return -ENOMEM;
|
|
|
|
result = -EINVAL;
|
|
|
|
down_write(&minors_rwsem);
|
|
|
|
for (minor = 0; minor < HIDRAW_MAX_DEVICES; minor++) {
|
|
if (hidraw_table[minor])
|
|
continue;
|
|
hidraw_table[minor] = dev;
|
|
result = 0;
|
|
break;
|
|
}
|
|
|
|
if (result) {
|
|
up_write(&minors_rwsem);
|
|
kfree(dev);
|
|
goto out;
|
|
}
|
|
|
|
dev->dev = device_create(hidraw_class, &hid->dev, MKDEV(hidraw_major, minor),
|
|
NULL, "%s%d", "hidraw", minor);
|
|
|
|
if (IS_ERR(dev->dev)) {
|
|
hidraw_table[minor] = NULL;
|
|
up_write(&minors_rwsem);
|
|
result = PTR_ERR(dev->dev);
|
|
kfree(dev);
|
|
goto out;
|
|
}
|
|
|
|
init_waitqueue_head(&dev->wait);
|
|
spin_lock_init(&dev->list_lock);
|
|
INIT_LIST_HEAD(&dev->list);
|
|
|
|
dev->hid = hid;
|
|
dev->minor = minor;
|
|
|
|
dev->exist = 1;
|
|
hid->hidraw = dev;
|
|
|
|
up_write(&minors_rwsem);
|
|
out:
|
|
return result;
|
|
|
|
}
|
|
EXPORT_SYMBOL_GPL(hidraw_connect);
|
|
|
|
void hidraw_disconnect(struct hid_device *hid)
|
|
{
|
|
struct hidraw *hidraw = hid->hidraw;
|
|
|
|
down_write(&minors_rwsem);
|
|
|
|
drop_ref(hidraw, 1);
|
|
|
|
up_write(&minors_rwsem);
|
|
}
|
|
EXPORT_SYMBOL_GPL(hidraw_disconnect);
|
|
|
|
int __init hidraw_init(void)
|
|
{
|
|
int result;
|
|
dev_t dev_id;
|
|
|
|
result = alloc_chrdev_region(&dev_id, HIDRAW_FIRST_MINOR,
|
|
HIDRAW_MAX_DEVICES, "hidraw");
|
|
if (result < 0) {
|
|
pr_warn("can't get major number\n");
|
|
goto out;
|
|
}
|
|
|
|
hidraw_major = MAJOR(dev_id);
|
|
|
|
hidraw_class = class_create(THIS_MODULE, "hidraw");
|
|
if (IS_ERR(hidraw_class)) {
|
|
result = PTR_ERR(hidraw_class);
|
|
goto error_cdev;
|
|
}
|
|
|
|
cdev_init(&hidraw_cdev, &hidraw_ops);
|
|
result = cdev_add(&hidraw_cdev, dev_id, HIDRAW_MAX_DEVICES);
|
|
if (result < 0)
|
|
goto error_class;
|
|
|
|
pr_info("raw HID events driver (C) Jiri Kosina\n");
|
|
out:
|
|
return result;
|
|
|
|
error_class:
|
|
class_destroy(hidraw_class);
|
|
error_cdev:
|
|
unregister_chrdev_region(dev_id, HIDRAW_MAX_DEVICES);
|
|
goto out;
|
|
}
|
|
|
|
void hidraw_exit(void)
|
|
{
|
|
dev_t dev_id = MKDEV(hidraw_major, 0);
|
|
|
|
cdev_del(&hidraw_cdev);
|
|
class_destroy(hidraw_class);
|
|
unregister_chrdev_region(dev_id, HIDRAW_MAX_DEVICES);
|
|
|
|
}
|