Release 4.11 drivers/char/hw_random/core.c

/*
 * hw_random/core.c: HWRNG core API
 *
 * Copyright 2006 Michael Buesch <m@bues.ch>
 * Copyright 2005 (c) MontaVista Software, Inc.
 *
 * Please read Documentation/hw_random.txt for details on use.
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/hw_random.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/sched/signal.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>


#define RNG_MODULE_NAME		"hw_random"


static struct hwrng *current_rng;

static struct task_struct *hwrng_fill;
static LIST_HEAD(rng_list);
/* Protects rng_list and current_rng */
static DEFINE_MUTEX(rng_mutex);
/* Protects rng read functions, data_avail, rng_buffer and rng_fillbuf */
static DEFINE_MUTEX(reading_mutex);

static int data_avail;


static u8 *rng_buffer, *rng_fillbuf;

static unsigned short current_quality;

static unsigned short default_quality; 
/* = 0; default to "off" */

module_param(current_quality, ushort, 0644);
MODULE_PARM_DESC(current_quality,
		 "current hwrng entropy estimation per mill");
module_param(default_quality, ushort, 0644);
MODULE_PARM_DESC(default_quality,
		 "default entropy content of hwrng per mill");

static void drop_current_rng(void);
static int hwrng_init(struct hwrng *rng);
static void start_khwrngd(void);

static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
			       int wait);



static size_t rng_buffer_size(void)
{
	return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
}

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10
58.82%
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7
41.18%
2
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17
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3
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static void add_early_randomness(struct hwrng *rng)
{
	int bytes_read;
	size_t size = min_t(size_t, 16, rng_buffer_size());

	mutex_lock(&reading_mutex);
	bytes_read = rng_get_data(rng, rng_buffer, size, 1);
	mutex_unlock(&reading_mutex);
	if (bytes_read > 0)
		add_device_randomness(rng_buffer, bytes_read);
}

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Amit Shah
37
56.92%
1
33.33%
Andrew Lutomirski
16
24.62%
1
33.33%
Rusty Russell
12
18.46%
1
33.33%
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65
100.00%
3
100.00%



static inline void cleanup_rng(struct kref *kref)
{
	struct hwrng *rng = container_of(kref, struct hwrng, ref);

	if (rng->cleanup)
		rng->cleanup(rng);

	complete(&rng->cleanup_done);
}

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45
93.75%
2
66.67%
Herbert Xu
3
6.25%
1
33.33%
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48
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3
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static int set_current_rng(struct hwrng *rng)
{
	int err;

	BUG_ON(!mutex_is_locked(&rng_mutex));

	err = hwrng_init(rng);
	if (err)
		return err;

	drop_current_rng();
	current_rng = rng;

	return 0;
}

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Herbert Xu
24
50.00%
2
66.67%
Rusty Russell
24
50.00%
1
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48
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3
100.00%



static void drop_current_rng(void)
{
	BUG_ON(!mutex_is_locked(&rng_mutex));
	if (!current_rng)
		return;

	/* decrease last reference for triggering the cleanup */
	kref_put(&current_rng->ref, cleanup_rng);
	current_rng = NULL;
}

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/* Returns ERR_PTR(), NULL or refcounted hwrng */


static struct hwrng *get_current_rng(void)
{
	struct hwrng *rng;

	if (mutex_lock_interruptible(&rng_mutex))
		return ERR_PTR(-ERESTARTSYS);

	rng = current_rng;
	if (rng)
		kref_get(&rng->ref);

	mutex_unlock(&rng_mutex);
	return rng;
}

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55
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static void put_rng(struct hwrng *rng)
{
	/*
         * Hold rng_mutex here so we serialize in case they set_current_rng
         * on rng again immediately.
         */
	mutex_lock(&rng_mutex);
	if (rng)
		kref_put(&rng->ref, cleanup_rng);
	mutex_unlock(&rng_mutex);
}

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static int hwrng_init(struct hwrng *rng)
{
	if (kref_get_unless_zero(&rng->ref))
		goto skip_init;

	if (rng->init) {
		int ret;

		ret =  rng->init(rng);
		if (ret)
			return ret;
	}

	kref_init(&rng->ref);
	reinit_completion(&rng->cleanup_done);

skip_init:
	add_early_randomness(rng);

	current_quality = rng->quality ? : default_quality;
	if (current_quality > 1024)
		current_quality = 1024;

	if (current_quality == 0 && hwrng_fill)
		kthread_stop(hwrng_fill);
	if (current_quality > 0 && !hwrng_fill)
		start_khwrngd();

	return 0;
}

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36
29.75%
2
33.33%
Herbert Xu
31
25.62%
1
16.67%
Michael Büsch
24
19.83%
1
16.67%
Amit Shah
22
18.18%
1
16.67%
Keith Packard
8
6.61%
1
16.67%
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121
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6
100.00%



static int rng_dev_open(struct inode *inode, struct file *filp)
{
	/* enforce read-only access to this chrdev */
	if ((filp->f_mode & FMODE_READ) == 0)
		return -EINVAL;
	if (filp->f_mode & FMODE_WRITE)
		return -EINVAL;
	return 0;
}

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48
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48
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static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
			int wait) {
	int present;

	BUG_ON(!mutex_is_locked(&reading_mutex));
	if (rng->read)
		return rng->read(rng, (void *)buffer, size, wait);

	if (rng->data_present)
		present = rng->data_present(rng, wait);
	else
		present = 1;

	if (present)
		return rng->data_read(rng, (u32 *)buffer);

	return 0;
}

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Ian Molton
92
90.20%
1
50.00%
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10
9.80%
1
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102
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2
100.00%



static ssize_t rng_dev_read(struct file *filp, char __user *buf,
			    size_t size, loff_t *offp)
{
	ssize_t ret = 0;
	int err = 0;
	int bytes_read, len;
	struct hwrng *rng;

	while (size) {
		rng = get_current_rng();
		if (IS_ERR(rng)) {
			err = PTR_ERR(rng);
			goto out;
		}
		if (!rng) {
			err = -ENODEV;
			goto out;
		}

		if (mutex_lock_interruptible(&reading_mutex)) {
			err = -ERESTARTSYS;
			goto out_put;
		}
		if (!data_avail) {
			bytes_read = rng_get_data(rng, rng_buffer,
				rng_buffer_size(),
				!(filp->f_flags & O_NONBLOCK));
			if (bytes_read < 0) {
				err = bytes_read;
				goto out_unlock_reading;
			}
			data_avail = bytes_read;
		}

		if (!data_avail) {
			if (filp->f_flags & O_NONBLOCK) {
				err = -EAGAIN;
				goto out_unlock_reading;
			}
		} else {
			len = data_avail;
			if (len > size)
				len = size;

			data_avail -= len;

			if (copy_to_user(buf + ret, rng_buffer + data_avail,
								len)) {
				err = -EFAULT;
				goto out_unlock_reading;
			}

			size -= len;
			ret += len;
		}

		mutex_unlock(&reading_mutex);
		put_rng(rng);

		if (need_resched())
			schedule_timeout_interruptible(1);

		if (signal_pending(current)) {
			err = -ERESTARTSYS;
			goto out;
		}
	}
out:
	return ret ? : err;

out_unlock_reading:
	mutex_unlock(&reading_mutex);
out_put:
	put_rng(rng);
	goto out;
}

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Michael Büsch
118
39.86%
1
11.11%
Ian Molton
95
32.09%
1
11.11%
Rusty Russell
45
15.20%
3
33.33%
Jiri Slaby
15
5.07%
1
11.11%
Ralph Wuerthner
14
4.73%
1
11.11%
Herbert Xu
8
2.70%
1
11.11%
Patrick McHardy
1
0.34%
1
11.11%
Total
296
100.00%
9
100.00%


static const struct file_operations rng_chrdev_ops = {
	.owner		= THIS_MODULE,
	.open		= rng_dev_open,
	.read		= rng_dev_read,
	.llseek		= noop_llseek,
};


static const struct attribute_group *rng_dev_groups[];


static struct miscdevice rng_miscdev = {
	.minor		= HWRNG_MINOR,
	.name		= RNG_MODULE_NAME,
	.nodename	= "hwrng",
	.fops		= &rng_chrdev_ops,
	.groups		= rng_dev_groups,
};



static ssize_t hwrng_attr_current_store(struct device *dev,
					struct device_attribute *attr,
					const char *buf, size_t len)
{
	int err;
	struct hwrng *rng;

	err = mutex_lock_interruptible(&rng_mutex);
	if (err)
		return -ERESTARTSYS;
	err = -ENODEV;
	list_for_each_entry(rng, &rng_list, list) {
		if (sysfs_streq(rng->name, buf)) {
			err = 0;
			if (rng != current_rng)
				err = set_current_rng(rng);
			break;
		}
	}
	mutex_unlock(&rng_mutex);

	return err ? : len;
}

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Michael Büsch
90
84.91%
1
20.00%
Greg Kroah-Hartman
7
6.60%
1
20.00%
Herbert Xu
5
4.72%
1
20.00%
Rusty Russell
3
2.83%
1
20.00%
Lee Jones
1
0.94%
1
20.00%
Total
106
100.00%
5
100.00%



static ssize_t hwrng_attr_current_show(struct device *dev,
				       struct device_attribute *attr,
				       char *buf)
{
	ssize_t ret;
	struct hwrng *rng;

	rng = get_current_rng();
	if (IS_ERR(rng))
		return PTR_ERR(rng);

	ret = snprintf(buf, PAGE_SIZE, "%s\n", rng ? rng->name : "none");
	put_rng(rng);

	return ret;
}

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Michael Büsch
44
60.27%
1
33.33%
Rusty Russell
22
30.14%
1
33.33%
Greg Kroah-Hartman
7
9.59%
1
33.33%
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73
100.00%
3
100.00%



static ssize_t hwrng_attr_available_show(struct device *dev,
					 struct device_attribute *attr,
					 char *buf)
{
	int err;
	struct hwrng *rng;

	err = mutex_lock_interruptible(&rng_mutex);
	if (err)
		return -ERESTARTSYS;
	buf[0] = '\0';
	list_for_each_entry(rng, &rng_list, list) {
		strlcat(buf, rng->name, PAGE_SIZE);
		strlcat(buf, " ", PAGE_SIZE);
	}
	strlcat(buf, "\n", PAGE_SIZE);
	mutex_unlock(&rng_mutex);

	return strlen(buf);
}

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Michael Büsch
88
86.27%
1
33.33%
Greg Kroah-Hartman
7
6.86%
1
33.33%
Rickard Strandqvist
7
6.86%
1
33.33%
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102
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3
100.00%

static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
		   hwrng_attr_current_show,
		   hwrng_attr_current_store);
static DEVICE_ATTR(rng_available, S_IRUGO,
		   hwrng_attr_available_show,
		   NULL);


static struct attribute *rng_dev_attrs[] = {
	&dev_attr_rng_current.attr,
	&dev_attr_rng_available.attr,
	NULL
};


ATTRIBUTE_GROUPS(rng_dev);



static void __exit unregister_miscdev(void)
{
	misc_deregister(&rng_miscdev);
}

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12
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1
33.33%
Rafael J. Wysocki
2
13.33%
1
33.33%
Herbert Xu
1
6.67%
1
33.33%
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15
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3
100.00%



static int __init register_miscdev(void)
{
	return misc_register(&rng_miscdev);
}

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Michael Büsch
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87.50%
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33.33%
Herbert Xu
1
6.25%
1
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Takashi Iwai
1
6.25%
1
33.33%
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16
100.00%
3
100.00%



static int hwrng_fillfn(void *unused)
{
	long rc;

	while (!kthread_should_stop()) {
		struct hwrng *rng;

		rng = get_current_rng();
		if (IS_ERR(rng) || !rng)
			break;
		mutex_lock(&reading_mutex);
		rc = rng_get_data(rng, rng_fillbuf,
				  rng_buffer_size(), 1);
		mutex_unlock(&reading_mutex);
		put_rng(rng);
		if (rc <= 0) {
			pr_warn("hwrng: no data available\n");
			msleep_interruptible(10000);
			continue;
		}
		/* Outside lock, sure, but y'know: randomness. */
		add_hwgenerator_randomness((void *)rng_fillbuf, rc,
					   rc * current_quality * 8 >> 10);
	}
	hwrng_fill = NULL;
	return 0;
}

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Torsten Duwe
82
68.91%
2
40.00%
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35
29.41%
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Stephen Boyd
2
1.68%
1
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119
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5
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static void start_khwrngd(void)
{
	hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng");
	if (IS_ERR(hwrng_fill)) {
		pr_err("hwrng_fill thread creation failed");
		hwrng_fill = NULL;
	}
}

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int hwrng_register(struct hwrng *rng)
{
	int err = -EINVAL;
	struct hwrng *old_rng, *tmp;

	if (!rng->name || (!rng->data_read && !rng->read))
		goto out;

	mutex_lock(&rng_mutex);
	/* Must not register two RNGs with the same name. */
	err = -EEXIST;
	list_for_each_entry(tmp, &rng_list, list) {
		if (strcmp(tmp->name, rng->name) == 0)
			goto out_unlock;
	}

	init_completion(&rng->cleanup_done);
	complete(&rng->cleanup_done);

	old_rng = current_rng;
	err = 0;
	if (!old_rng) {
		err = set_current_rng(rng);
		if (err)
			goto out_unlock;
	}
	list_add_tail(&rng->list, &rng_list);

	if (old_rng && !rng->init) {
		/*
                 * Use a new device's input to add some randomness to
                 * the system.  If this rng device isn't going to be
                 * used right away, its init function hasn't been
                 * called yet; so only use the randomness from devices
                 * that don't need an init callback.
                 */
		add_early_randomness(rng);
	}

out_unlock:
	mutex_unlock(&rng_mutex);
out:
	return err;
}
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12.50%
Herbert Xu
17
9.88%
2
25.00%
Amit Shah
11
6.40%
1
12.50%
Kees Cook
6
3.49%
1
12.50%
Ian Molton
6
3.49%
1
12.50%
Rusty Russell
4
2.33%
1
12.50%
Corentin Labbe
3
1.74%
1
12.50%
Total
172
100.00%
8
100.00%


EXPORT_SYMBOL_GPL(hwrng_register);



void hwrng_unregister(struct hwrng *rng)
{
	mutex_lock(&rng_mutex);

	list_del(&rng->list);
	if (current_rng == rng) {
		drop_current_rng();
		if (!list_empty(&rng_list)) {
			struct hwrng *tail;

			tail = list_entry(rng_list.prev, struct hwrng, list);

			set_current_rng(tail);
		}
	}

	if (list_empty(&rng_list)) {
		mutex_unlock(&rng_mutex);
		if (hwrng_fill)
			kthread_stop(hwrng_fill);
	} else
		mutex_unlock(&rng_mutex);

	wait_for_completion(&rng->cleanup_done);
}
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Michael Büsch
70
63.64%
1
14.29%
Rusty Russell
19
17.27%
2
28.57%
Torsten Duwe
11
10.00%
1
14.29%
Amos Kong
7
6.36%
1
14.29%
Herbert Xu
2
1.82%
1
14.29%
Rafael J. Wysocki
1
0.91%
1
14.29%
Total
110
100.00%
7
100.00%


EXPORT_SYMBOL_GPL(hwrng_unregister);



static void devm_hwrng_release(struct device *dev, void *res)
{
	hwrng_unregister(*(struct hwrng **)res);
}

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static int devm_hwrng_match(struct device *dev, void *res, void *data)
{
	struct hwrng **r = res;

	if (WARN_ON(!r || !*r))
		return 0;

	return *r == data;
}

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48
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int devm_hwrng_register(struct device *dev, struct hwrng *rng)
{
	struct hwrng **ptr;
	int error;

	ptr = devres_alloc(devm_hwrng_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return -ENOMEM;

	error = hwrng_register(rng);
	if (error) {
		devres_free(ptr);
		return error;
	}

	*ptr = rng;
	devres_add(dev, ptr);
	return 0;
}
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84
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1
100.00%


EXPORT_SYMBOL_GPL(devm_hwrng_register);



void devm_hwrng_unregister(struct device *dev, struct hwrng *rng)
{
	devres_release(dev, devm_hwrng_release, devm_hwrng_match, rng);
}
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26
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EXPORT_SYMBOL_GPL(devm_hwrng_unregister);



static int __init hwrng_modinit(void)
{
	int ret = -ENOMEM;

	/* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
	rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
	if (!rng_buffer)
		return -ENOMEM;

	rng_fillbuf = kmalloc(rng_buffer_size(), GFP_KERNEL);
	if (!rng_fillbuf) {
		kfree(rng_buffer);
		return -ENOMEM;
	}

	ret = register_miscdev();
	if (ret) {
		kfree(rng_fillbuf);
		kfree(rng_buffer);
	}

	return ret;
}

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PrasannaKumar Muralidharan
72
84.71%
1
50.00%
Herbert Xu
13
15.29%
1
50.00%
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85
100.00%
2
100.00%



static void __exit hwrng_modexit(void)
{
	mutex_lock(&rng_mutex);
	BUG_ON(current_rng);
	kfree(rng_buffer);
	kfree(rng_fillbuf);
	mutex_unlock(&rng_mutex);

	unregister_miscdev();
}

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Satoru Takeuchi
30
76.92%
1
33.33%
Torsten Duwe
5
12.82%
1
33.33%
Herbert Xu
4
10.26%
1
33.33%
Total
39
100.00%
3
100.00%


module_init(hwrng_modinit);

module_exit(hwrng_modexit);

MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
MODULE_LICENSE("GPL");
Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Michael Büsch
759
33.33%
1
2.17%
Rusty Russell
377
16.56%
5
10.87%
Torsten Duwe
229
10.06%
3
6.52%
Ian Molton
207
9.09%
2
4.35%
Dmitry Torokhov
195
8.56%
1
2.17%
Herbert Xu
132
5.80%
6
13.04%
Amit Shah
91
4.00%
1
2.17%
PrasannaKumar Muralidharan
72
3.16%
1
2.17%
Takashi Iwai
40
1.76%
1
2.17%
Satoru Takeuchi
34
1.49%
1
2.17%
Greg Kroah-Hartman
23
1.01%
1
2.17%
Corentin Labbe
17
0.75%
4
8.70%
Andrew Lutomirski
16
0.70%
1
2.17%
Jiri Slaby
15
0.66%
1
2.17%
Ralph Wuerthner
14
0.61%
1
2.17%
Kees Cook
8
0.35%
1
2.17%
Keith Packard
8
0.35%
1
2.17%
Amos Kong
7
0.31%
1
2.17%
Rickard Strandqvist
7
0.31%
1
2.17%
Arnd Bergmann
5
0.22%
1
2.17%
Kay Sievers
5
0.22%
2
4.35%
Rafael J. Wysocki
4
0.18%
1
2.17%
Ingo Molnar
3
0.13%
1
2.17%
Stephen Boyd
2
0.09%
1
2.17%
Martin Schwidefsky
2
0.09%
1
2.17%
Linus Torvalds
1
0.04%
1
2.17%
Patrick McHardy
1
0.04%
1
2.17%
Lee Jones
1
0.04%
1
2.17%
Arjan van de Ven
1
0.04%
1
2.17%
Al Viro
1
0.04%
1
2.17%
Total
2277
100.00%
46
100.00%
Directory: drivers/char/hw_random

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