cregit-Linux how code gets into the kernel

Release 4.14 drivers/media/media-devnode.c

Directory: drivers/media
/*
 * Media device node
 *
 * Copyright (C) 2010 Nokia Corporation
 *
 * Based on drivers/media/video/v4l2_dev.c code authored by
 *      Mauro Carvalho Chehab <mchehab@infradead.org> (version 2)
 *      Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1)
 *
 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
 *           Sakari Ailus <sakari.ailus@iki.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * --
 *
 * Generic media device node infrastructure to register and unregister
 * character devices using a dynamic major number and proper reference
 * counting.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/uaccess.h>

#include <media/media-devnode.h>
#include <media/media-device.h>


#define MEDIA_NUM_DEVICES	256

#define MEDIA_NAME		"media"


static dev_t media_dev_t;

/*
 *      Active devices
 */
static DEFINE_MUTEX(media_devnode_lock);
static DECLARE_BITMAP(media_devnode_nums, MEDIA_NUM_DEVICES);

/* Called when the last user of the media device exits. */

static void media_devnode_release(struct device *cd) { struct media_devnode *devnode = to_media_devnode(cd); mutex_lock(&media_devnode_lock); /* Mark device node number as free */ clear_bit(devnode->minor, media_devnode_nums); mutex_unlock(&media_devnode_lock); /* Release media_devnode and perform other cleanups as needed. */ if (devnode->release) devnode->release(devnode); kfree(devnode); pr_debug("%s: Media Devnode Deallocated\n", __func__); }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart5275.36%125.00%
Mauro Carvalho Chehab1014.49%250.00%
Shuah Khan710.14%125.00%
Total69100.00%4100.00%

static struct bus_type media_bus_type = { .name = MEDIA_NAME, };
static ssize_t media_read(struct file *filp, char __user *buf, size_t sz, loff_t *off) { struct media_devnode *devnode = media_devnode_data(filp); if (!devnode->fops->read) return -EINVAL; if (!media_devnode_is_registered(devnode)) return -EIO; return devnode->fops->read(filp, buf, sz, off); }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart7094.59%150.00%
Mauro Carvalho Chehab45.41%150.00%
Total74100.00%2100.00%


static ssize_t media_write(struct file *filp, const char __user *buf, size_t sz, loff_t *off) { struct media_devnode *devnode = media_devnode_data(filp); if (!devnode->fops->write) return -EINVAL; if (!media_devnode_is_registered(devnode)) return -EIO; return devnode->fops->write(filp, buf, sz, off); }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart7194.67%150.00%
Mauro Carvalho Chehab45.33%150.00%
Total75100.00%2100.00%


static unsigned int media_poll(struct file *filp, struct poll_table_struct *poll) { struct media_devnode *devnode = media_devnode_data(filp); if (!media_devnode_is_registered(devnode)) return POLLERR | POLLHUP; if (!devnode->fops->poll) return DEFAULT_POLLMASK; return devnode->fops->poll(filp, poll); }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart6093.75%150.00%
Mauro Carvalho Chehab46.25%150.00%
Total64100.00%2100.00%


static long __media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg, long (*ioctl_func)(struct file *filp, unsigned int cmd, unsigned long arg)) { struct media_devnode *devnode = media_devnode_data(filp); if (!ioctl_func) return -ENOTTY; if (!media_devnode_is_registered(devnode)) return -EIO; return ioctl_func(filp, cmd, arg); }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart4657.50%133.33%
Sakari Ailus3240.00%133.33%
Mauro Carvalho Chehab22.50%133.33%
Total80100.00%3100.00%


static long media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { struct media_devnode *devnode = media_devnode_data(filp); return __media_ioctl(filp, cmd, arg, devnode->fops->ioctl); }

Contributors

PersonTokensPropCommitsCommitProp
Sakari Ailus3986.67%133.33%
Laurent Pinchart48.89%133.33%
Mauro Carvalho Chehab24.44%133.33%
Total45100.00%3100.00%

#ifdef CONFIG_COMPAT
static long media_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { struct media_devnode *devnode = media_devnode_data(filp); return __media_ioctl(filp, cmd, arg, devnode->fops->compat_ioctl); }

Contributors

PersonTokensPropCommitsCommitProp
Sakari Ailus3475.56%133.33%
Laurent Pinchart920.00%133.33%
Mauro Carvalho Chehab24.44%133.33%
Total45100.00%3100.00%

#endif /* CONFIG_COMPAT */ /* Override for the open function */
static int media_open(struct inode *inode, struct file *filp) { struct media_devnode *devnode; int ret; /* Check if the media device is available. This needs to be done with * the media_devnode_lock held to prevent an open/unregister race: * without the lock, the device could be unregistered and freed between * the media_devnode_is_registered() and get_device() calls, leading to * a crash. */ mutex_lock(&media_devnode_lock); devnode = container_of(inode->i_cdev, struct media_devnode, cdev); /* return ENXIO if the media device has been removed already or if it is not registered anymore. */ if (!media_devnode_is_registered(devnode)) { mutex_unlock(&media_devnode_lock); return -ENXIO; } /* and increase the device refcount */ get_device(&devnode->dev); mutex_unlock(&media_devnode_lock); filp->private_data = devnode; if (devnode->fops->open) { ret = devnode->fops->open(filp); if (ret) { put_device(&devnode->dev); filp->private_data = NULL; return ret; } } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart12089.55%133.33%
Mauro Carvalho Chehab85.97%133.33%
Shuah Khan64.48%133.33%
Total134100.00%3100.00%

/* Override for the release function */
static int media_release(struct inode *inode, struct file *filp) { struct media_devnode *devnode = media_devnode_data(filp); if (devnode->fops->release) devnode->fops->release(filp); filp->private_data = NULL; /* decrease the refcount unconditionally since the release() return value is ignored. */ put_device(&devnode->dev); pr_debug("%s: Media Release\n", __func__); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart5073.53%120.00%
Shuah Khan710.29%120.00%
Max Kellermann68.82%120.00%
Mauro Carvalho Chehab57.35%240.00%
Total68100.00%5100.00%

static const struct file_operations media_devnode_fops = { .owner = THIS_MODULE, .read = media_read, .write = media_write, .open = media_open, .unlocked_ioctl = media_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = media_compat_ioctl, #endif /* CONFIG_COMPAT */ .release = media_release, .poll = media_poll, .llseek = no_llseek, };
int __must_check media_devnode_register(struct media_device *mdev, struct media_devnode *devnode, struct module *owner) { int minor; int ret; /* Part 1: Find a free minor number */ mutex_lock(&media_devnode_lock); minor = find_next_zero_bit(media_devnode_nums, MEDIA_NUM_DEVICES, 0); if (minor == MEDIA_NUM_DEVICES) { mutex_unlock(&media_devnode_lock); pr_err("could not get a free minor\n"); kfree(devnode); return -ENFILE; } set_bit(minor, media_devnode_nums); mutex_unlock(&media_devnode_lock); devnode->minor = minor; devnode->media_dev = mdev; /* Part 1: Initialize dev now to use dev.kobj for cdev.kobj.parent */ devnode->dev.bus = &media_bus_type; devnode->dev.devt = MKDEV(MAJOR(media_dev_t), devnode->minor); devnode->dev.release = media_devnode_release; if (devnode->parent) devnode->dev.parent = devnode->parent; dev_set_name(&devnode->dev, "media%d", devnode->minor); device_initialize(&devnode->dev); /* Part 2: Initialize the character device */ cdev_init(&devnode->cdev, &media_devnode_fops); devnode->cdev.owner = owner; /* Part 3: Add the media and char device */ ret = cdev_device_add(&devnode->cdev, &devnode->dev); if (ret < 0) { pr_err("%s: cdev_device_add failed\n", __func__); goto cdev_add_error; } /* Part 4: Activate this minor. The char device can now be used. */ set_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); return 0; cdev_add_error: mutex_lock(&media_devnode_lock); clear_bit(devnode->minor, media_devnode_nums); devnode->media_dev = NULL; mutex_unlock(&media_devnode_lock); put_device(&devnode->dev); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart17462.14%222.22%
Shuah Khan6322.50%111.11%
Mauro Carvalho Chehab258.93%222.22%
Max Kellermann62.14%111.11%
Logan Gunthorpe51.79%111.11%
Sakari Ailus51.79%111.11%
Sachin Kamat20.71%111.11%
Total280100.00%9100.00%


void media_devnode_unregister_prepare(struct media_devnode *devnode) { /* Check if devnode was ever registered at all */ if (!media_devnode_is_registered(devnode)) return; mutex_lock(&media_devnode_lock); clear_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); mutex_unlock(&media_devnode_lock); }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart3071.43%133.33%
Shuah Khan819.05%133.33%
Mauro Carvalho Chehab49.52%133.33%
Total42100.00%3100.00%


void media_devnode_unregister(struct media_devnode *devnode) { mutex_lock(&media_devnode_lock); /* Delete the cdev on this minor as well */ cdev_device_del(&devnode->cdev, &devnode->dev); mutex_unlock(&media_devnode_lock); devnode->media_dev = NULL; put_device(&devnode->dev); }

Contributors

PersonTokensPropCommitsCommitProp
Shuah Khan3060.00%240.00%
Laurent Pinchart1326.00%120.00%
Logan Gunthorpe612.00%120.00%
Mauro Carvalho Chehab12.00%120.00%
Total50100.00%5100.00%

/* * Initialise media for linux */
static int __init media_devnode_init(void) { int ret; pr_info("Linux media interface: v0.10\n"); ret = alloc_chrdev_region(&media_dev_t, 0, MEDIA_NUM_DEVICES, MEDIA_NAME); if (ret < 0) { pr_warn("unable to allocate major\n"); return ret; } ret = bus_register(&media_bus_type); if (ret < 0) { unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES); pr_warn("bus_register failed\n"); return -EIO; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart7793.90%150.00%
Sachin Kamat56.10%150.00%
Total82100.00%2100.00%


static void __exit media_devnode_exit(void) { bus_unregister(&media_bus_type); unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES); }

Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart22100.00%1100.00%
Total22100.00%1100.00%

subsys_initcall(media_devnode_init); module_exit(media_devnode_exit) MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>"); MODULE_DESCRIPTION("Device node registration for media drivers"); MODULE_LICENSE("GPL");

Overall Contributors

PersonTokensPropCommitsCommitProp
Laurent Pinchart94672.43%318.75%
Sakari Ailus1289.80%318.75%
Shuah Khan1219.26%318.75%
Mauro Carvalho Chehab745.67%318.75%
Sachin Kamat141.07%16.25%
Max Kellermann120.92%212.50%
Logan Gunthorpe110.84%16.25%
Total1306100.00%16100.00%
Directory: drivers/media
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