// SPDX-License-Identifier: GPL-2.0/* * linux/fs/char_dev.c * * Copyright (C) 1991, 1992 Linus Torvalds */ #include <linux/init.h>#include <linux/fs.h>#include <linux/kdev_t.h>#include <linux/slab.h>#include <linux/string.h> #include <linux/major.h>#include <linux/errno.h>#include <linux/module.h>#include <linux/seq_file.h> #include <linux/kobject.h>#include <linux/kobj_map.h>#include <linux/cdev.h>#include <linux/mutex.h>#include <linux/backing-dev.h>#include <linux/tty.h> #include "internal.h" static struct kobj_map *cdev_map __ro_after_init; static DEFINE_MUTEX(chrdevs_lock); #define CHRDEV_MAJOR_HASH_SIZE 255 static struct char_device_struct { struct char_device_struct *next; unsigned int major; unsigned int baseminor; int minorct; char name[64]; struct cdev *cdev; /* will die */} *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; /* index in the above */static inline int major_to_index(unsigned major){ return major % CHRDEV_MAJOR_HASH_SIZE;} #ifdef CONFIG_PROC_FS void chrdev_show(struct seq_file *f, off_t offset){ struct char_device_struct *cd; mutex_lock(&chrdevs_lock); for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) { if (cd->major == offset) seq_printf(f, "%3d %s\n", cd->major, cd->name); } mutex_unlock(&chrdevs_lock);} #endif /* CONFIG_PROC_FS */ static int find_dynamic_major(void){ int i; struct char_device_struct *cd; for (i = ARRAY_SIZE(chrdevs)-1; i >= CHRDEV_MAJOR_DYN_END; i--) { if (chrdevs[i] == NULL) return i; } for (i = CHRDEV_MAJOR_DYN_EXT_START; i >= CHRDEV_MAJOR_DYN_EXT_END; i--) { for (cd = chrdevs[major_to_index(i)]; cd; cd = cd->next) if (cd->major == i) break; if (cd == NULL) return i; } return -EBUSY;} /* * Register a single major with a specified minor range. * * If major == 0 this function will dynamically allocate an unused major. * If major > 0 this function will attempt to reserve the range of minors * with given major. * */static struct char_device_struct *__register_chrdev_region(unsigned int major, unsigned int baseminor, int minorct, const char *name){ struct char_device_struct *cd, *curr, *prev = NULL; int ret; int i; if (major >= CHRDEV_MAJOR_MAX) { pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n", name, major, CHRDEV_MAJOR_MAX-1); return ERR_PTR(-EINVAL); } if (minorct > MINORMASK + 1 - baseminor) { pr_err("CHRDEV \"%s\" minor range requested (%u-%u) is out of range of maximum range (%u-%u) for a single major\n", name, baseminor, baseminor + minorct - 1, 0, MINORMASK); return ERR_PTR(-EINVAL); } cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); if (cd == NULL) return ERR_PTR(-ENOMEM); mutex_lock(&chrdevs_lock); if (major == 0) { ret = find_dynamic_major(); if (ret < 0) { pr_err("CHRDEV \"%s\" dynamic allocation region is full\n", name); goto out; } major = ret; } ret = -EBUSY; i = major_to_index(major); for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) { if (curr->major < major) continue; if (curr->major > major) break; if (curr->baseminor + curr->minorct <= baseminor) continue; if (curr->baseminor >= baseminor + minorct) break; goto out; } cd->major = major; cd->baseminor = baseminor; cd->minorct = minorct; strscpy(cd->name, name, sizeof(cd->name)); if (!prev) { cd->next = curr; chrdevs[i] = cd; } else { cd->next = prev->next; prev->next = cd; } mutex_unlock(&chrdevs_lock); return cd;out: mutex_unlock(&chrdevs_lock); kfree(cd); return ERR_PTR(ret);} static struct char_device_struct *__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct){ struct char_device_struct *cd = NULL, **cp; int i = major_to_index(major); mutex_lock(&chrdevs_lock); for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) if ((*cp)->major == major && (*cp)->baseminor == baseminor && (*cp)->minorct == minorct) break; if (*cp) { cd = *cp; *cp = cd->next; } mutex_unlock(&chrdevs_lock); return cd;} /** * register_chrdev_region() - register a range of device numbers * @from: the first in the desired range of device numbers; must include * the major number. * @count: the number of consecutive device numbers required * @name: the name of the device or driver. * * Return value is zero on success, a negative error code on failure. */int register_chrdev_region(dev_t from, unsigned count, const char *name){ struct char_device_struct *cd; dev_t to = from + count; dev_t n, next; for (n = from; n < to; n = next) { next = MKDEV(MAJOR(n)+1, 0); if (next > to) next = to; cd = __register_chrdev_region(MAJOR(n), MINOR(n), next - n, name); if (IS_ERR(cd)) goto fail; } return 0;fail: to = n; for (n = from; n < to; n = next) { next = MKDEV(MAJOR(n)+1, 0); kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); } return PTR_ERR(cd);} /** * alloc_chrdev_region() - register a range of char device numbers * @dev: output parameter for first assigned number * @baseminor: first of the requested range of minor numbers * @count: the number of minor numbers required * @name: the name of the associated device or driver * * Allocates a range of char device numbers. The major number will be * chosen dynamically, and returned (along with the first minor number) * in @dev. Returns zero or a negative error code. */int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, const char *name){ struct char_device_struct *cd; cd = __register_chrdev_region(0, baseminor, count, name); if (IS_ERR(cd)) return PTR_ERR(cd); *dev = MKDEV(cd->major, cd->baseminor); return 0;} /** * __register_chrdev() - create and register a cdev occupying a range of minors * @major: major device number or 0 for dynamic allocation * @baseminor: first of the requested range of minor numbers * @count: the number of minor numbers required * @name: name of this range of devices * @fops: file operations associated with this devices * * If @major == 0 this functions will dynamically allocate a major and return * its number. * * If @major > 0 this function will attempt to reserve a device with the given * major number and will return zero on success. * * Returns a -ve errno on failure. * * The name of this device has nothing to do with the name of the device in * /dev. It only helps to keep track of the different owners of devices. If * your module name has only one type of devices it's ok to use e.g. the name * of the module here. */int __register_chrdev(unsigned int major, unsigned int baseminor, unsigned int count, const char *name, const struct file_operations *fops){ struct char_device_struct *cd; struct cdev *cdev; int err = -ENOMEM; cd = __register_chrdev_region(major, baseminor, count, name); if (IS_ERR(cd)) return PTR_ERR(cd); cdev = cdev_alloc(); if (!cdev) goto out2; cdev->owner = fops->owner; cdev->ops = fops; kobject_set_name(&cdev->kobj, "%s", name); err = cdev_add(cdev, MKDEV(cd->major, baseminor), count); if (err) goto out; cd->cdev = cdev; return major ? 0 : cd->major;out: kobject_put(&cdev->kobj);out2: kfree(__unregister_chrdev_region(cd->major, baseminor, count)); return err;} /** * unregister_chrdev_region() - unregister a range of device numbers * @from: the first in the range of numbers to unregister * @count: the number of device numbers to unregister * * This function will unregister a range of @count device numbers, * starting with @from. The caller should normally be the one who * allocated those numbers in the first place... */void unregister_chrdev_region(dev_t from, unsigned count){ dev_t to = from + count; dev_t n, next; for (n = from; n < to; n = next) { next = MKDEV(MAJOR(n)+1, 0); if (next > to) next = to; kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); }} /** * __unregister_chrdev - unregister and destroy a cdev * @major: major device number * @baseminor: first of the range of minor numbers * @count: the number of minor numbers this cdev is occupying * @name: name of this range of devices * * Unregister and destroy the cdev occupying the region described by * @major, @baseminor and @count. This function undoes what * __register_chrdev() did. */void __unregister_chrdev(unsigned int major, unsigned int baseminor, unsigned int count, const char *name){ struct char_device_struct *cd; cd = __unregister_chrdev_region(major, baseminor, count); if (cd && cd->cdev) cdev_del(cd->cdev); kfree(cd);} static DEFINE_SPINLOCK(cdev_lock); static struct kobject *cdev_get(struct cdev *p){ struct module *owner = p->owner; struct kobject *kobj; if (!try_module_get(owner)) return NULL; kobj = kobject_get_unless_zero(&p->kobj); if (!kobj) module_put(owner); return kobj;} void cdev_put(struct cdev *p){ if (p) { struct module *owner = p->owner; kobject_put(&p->kobj); module_put(owner); }} /* * Called every time a character special file is opened */static int chrdev_open(struct inode *inode, struct file *filp){ const struct file_operations *fops; struct cdev *p; struct cdev *new = NULL; int ret = 0; spin_lock(&cdev_lock); p = inode->i_cdev; if (!p) { struct kobject *kobj; int idx; spin_unlock(&cdev_lock); kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); if (!kobj) return -ENXIO; new = container_of(kobj, struct cdev, kobj); spin_lock(&cdev_lock); /* Check i_cdev again in case somebody beat us to it while we dropped the lock. */ p = inode->i_cdev; if (!p) { inode->i_cdev = p = new; list_add(&inode->i_devices, &p->list); new = NULL; } else if (!cdev_get(p)) ret = -ENXIO; } else if (!cdev_get(p)) ret = -ENXIO; spin_unlock(&cdev_lock); cdev_put(new); if (ret) return ret; ret = -ENXIO; fops = fops_get(p->ops); if (!fops) goto out_cdev_put; replace_fops(filp, fops); if (filp->f_op->open) { ret = filp->f_op->open(inode, filp); if (ret) goto out_cdev_put; } return 0; out_cdev_put: cdev_put(p); return ret;} void cd_forget(struct inode *inode){ spin_lock(&cdev_lock); list_del_init(&inode->i_devices); inode->i_cdev = NULL; inode->i_mapping = &inode->i_data; spin_unlock(&cdev_lock);} static void cdev_purge(struct cdev *cdev){ spin_lock(&cdev_lock); while (!list_empty(&cdev->list)) { struct inode *inode; inode = container_of(cdev->list.next, struct inode, i_devices); list_del_init(&inode->i_devices); inode->i_cdev = NULL; } spin_unlock(&cdev_lock);} /* * Dummy default file-operations: the only thing this does * is contain the open that then fills in the correct operations * depending on the special file... */const struct file_operations def_chr_fops = { .open = chrdev_open, .llseek = noop_llseek,}; static struct kobject *exact_match(dev_t dev, int *part, void *data){ struct cdev *p = data; return &p->kobj;} static int exact_lock(dev_t dev, void *data){ struct cdev *p = data; return cdev_get(p) ? 0 : -1;} /** * cdev_add() - add a char device to the system * @p: the cdev structure for the device * @dev: the first device number for which this device is responsible * @count: the number of consecutive minor numbers corresponding to this * device * * cdev_add() adds the device represented by @p to the system, making it * live immediately. A negative error code is returned on failure. */int cdev_add(struct cdev *p, dev_t dev, unsigned count){ int error; p->dev = dev; p->count = count; if (WARN_ON(dev == WHITEOUT_DEV)) { error = -EBUSY; goto err; } error = kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p); if (error) goto err; kobject_get(p->kobj.parent); return 0; err:Lines 1–500 of 692. Load more
// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/char_dev.c * * Copyright (C) 1991, 1992 Linus Torvalds */ #include <linux/init.h> #include <linux/fs.h> #include <linux/kdev_t.h> #include <linux/slab.h> #include <linux/string.h> #include <linux/major.h> #include <linux/errno.h> #include <linux/module.h> #include <linux/seq_file.h> #include <linux/kobject.h> #include <linux/kobj_map.h> #include <linux/cdev.h> #include <linux/mutex.h> #include <linux/backing-dev.h> #include <linux/tty.h> #include "internal.h" static struct kobj_map *cdev_map __ro_after_init; static DEFINE_MUTEX(chrdevs_lock); #define CHRDEV_MAJOR_HASH_SIZE 255 static struct char_device_struct { struct char_device_struct *next; unsigned int major; unsigned int baseminor; int minorct; char name[64]; struct cdev *cdev; /* will die */ } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; /* index in the above */ static inline int major_to_index(unsigned major) { return major % CHRDEV_MAJOR_HASH_SIZE; } #ifdef CONFIG_PROC_FS void chrdev_show(struct seq_file *f, off_t offset) { struct char_device_struct *cd; mutex_lock(&chrdevs_lock); for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) { if (cd->major == offset) seq_printf(f, "%3d %s\n", cd->major, cd->name); } mutex_unlock(&chrdevs_lock); } #endif /* CONFIG_PROC_FS */ static int find_dynamic_major(void) { int i; struct char_device_struct *cd; for (i = ARRAY_SIZE(chrdevs)-1; i >= CHRDEV_MAJOR_DYN_END; i--) { if (chrdevs[i] == NULL) return i; } for (i = CHRDEV_MAJOR_DYN_EXT_START; i >= CHRDEV_MAJOR_DYN_EXT_END; i--) { for (cd = chrdevs[major_to_index(i)]; cd; cd = cd->next) if (cd->major == i) break; if (cd == NULL) return i; } return -EBUSY; } /* * Register a single major with a specified minor range. * * If major == 0 this function will dynamically allocate an unused major. * If major > 0 this function will attempt to reserve the range of minors * with given major. * */ static struct char_device_struct * __register_chrdev_region(unsigned int major, unsigned int baseminor, int minorct, const char *name) { struct char_device_struct *cd, *curr, *prev = NULL; int ret; int i; if (major >= CHRDEV_MAJOR_MAX) { pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n", name, major, CHRDEV_MAJOR_MAX-1); return ERR_PTR(-EINVAL); } if (minorct > MINORMASK + 1 - baseminor) { pr_err("CHRDEV \"%s\" minor range requested (%u-%u) is out of range of maximum range (%u-%u) for a single major\n", name, baseminor, baseminor + minorct - 1, 0, MINORMASK); return ERR_PTR(-EINVAL); } cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); if (cd == NULL) return ERR_PTR(-ENOMEM); mutex_lock(&chrdevs_lock); if (major == 0) { ret = find_dynamic_major(); if (ret < 0) { pr_err("CHRDEV \"%s\" dynamic allocation region is full\n", name); goto out; } major = ret; } ret = -EBUSY; i = major_to_index(major); for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) { if (curr->major < major) continue; if (curr->major > major) break; if (curr->baseminor + curr->minorct <= baseminor) continue; if (curr->baseminor >= baseminor + minorct) break; goto out; } cd->major = major; cd->baseminor = baseminor; cd->minorct = minorct; strscpy(cd->name, name, sizeof(cd->name)); if (!prev) { cd->next = curr; chrdevs[i] = cd; } else { cd->next = prev->next; prev->next = cd; } mutex_unlock(&chrdevs_lock); return cd; out: mutex_unlock(&chrdevs_lock); kfree(cd); return ERR_PTR(ret); } static struct char_device_struct * __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) { struct char_device_struct *cd = NULL, **cp; int i = major_to_index(major); mutex_lock(&chrdevs_lock); for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) if ((*cp)->major == major && (*cp)->baseminor == baseminor && (*cp)->minorct == minorct) break; if (*cp) { cd = *cp; *cp = cd->next; } mutex_unlock(&chrdevs_lock); return cd; } /** * register_chrdev_region() - register a range of device numbers * @from: the first in the desired range of device numbers; must include * the major number. * @count: the number of consecutive device numbers required * @name: the name of the device or driver. * * Return value is zero on success, a negative error code on failure. */ int register_chrdev_region(dev_t from, unsigned count, const char *name) { struct char_device_struct *cd; dev_t to = from + count; dev_t n, next; for (n = from; n < to; n = next) { next = MKDEV(MAJOR(n)+1, 0); if (next > to) next = to; cd = __register_chrdev_region(MAJOR(n), MINOR(n), next - n, name); if (IS_ERR(cd)) goto fail; } return 0; fail: to = n; for (n = from; n < to; n = next) { next = MKDEV(MAJOR(n)+1, 0); kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); } return PTR_ERR(cd); } /** * alloc_chrdev_region() - register a range of char device numbers * @dev: output parameter for first assigned number * @baseminor: first of the requested range of minor numbers * @count: the number of minor numbers required * @name: the name of the associated device or driver * * Allocates a range of char device numbers. The major number will be * chosen dynamically, and returned (along with the first minor number) * in @dev. Returns zero or a negative error code. */ int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, const char *name) { struct char_device_struct *cd; cd = __register_chrdev_region(0, baseminor, count, name); if (IS_ERR(cd)) return PTR_ERR(cd); *dev = MKDEV(cd->major, cd->baseminor); return 0; } /** * __register_chrdev() - create and register a cdev occupying a range of minors * @major: major device number or 0 for dynamic allocation * @baseminor: first of the requested range of minor numbers * @count: the number of minor numbers required * @name: name of this range of devices * @fops: file operations associated with this devices * * If @major == 0 this functions will dynamically allocate a major and return * its number. * * If @major > 0 this function will attempt to reserve a device with the given * major number and will return zero on success. * * Returns a -ve errno on failure. * * The name of this device has nothing to do with the name of the device in * /dev. It only helps to keep track of the different owners of devices. If * your module name has only one type of devices it's ok to use e.g. the name * of the module here. */ int __register_chrdev(unsigned int major, unsigned int baseminor, unsigned int count, const char *name, const struct file_operations *fops) { struct char_device_struct *cd; struct cdev *cdev; int err = -ENOMEM; cd = __register_chrdev_region(major, baseminor, count, name); if (IS_ERR(cd)) return PTR_ERR(cd); cdev = cdev_alloc(); if (!cdev) goto out2; cdev->owner = fops->owner; cdev->ops = fops; kobject_set_name(&cdev->kobj, "%s", name); err = cdev_add(cdev, MKDEV(cd->major, baseminor), count); if (err) goto out; cd->cdev = cdev; return major ? 0 : cd->major; out: kobject_put(&cdev->kobj); out2: kfree(__unregister_chrdev_region(cd->major, baseminor, count)); return err; } /** * unregister_chrdev_region() - unregister a range of device numbers * @from: the first in the range of numbers to unregister * @count: the number of device numbers to unregister * * This function will unregister a range of @count device numbers, * starting with @from. The caller should normally be the one who * allocated those numbers in the first place... */ void unregister_chrdev_region(dev_t from, unsigned count) { dev_t to = from + count; dev_t n, next; for (n = from; n < to; n = next) { next = MKDEV(MAJOR(n)+1, 0); if (next > to) next = to; kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); } } /** * __unregister_chrdev - unregister and destroy a cdev * @major: major device number * @baseminor: first of the range of minor numbers * @count: the number of minor numbers this cdev is occupying * @name: name of this range of devices * * Unregister and destroy the cdev occupying the region described by * @major, @baseminor and @count. This function undoes what * __register_chrdev() did. */ void __unregister_chrdev(unsigned int major, unsigned int baseminor, unsigned int count, const char *name) { struct char_device_struct *cd; cd = __unregister_chrdev_region(major, baseminor, count); if (cd && cd->cdev) cdev_del(cd->cdev); kfree(cd); } static DEFINE_SPINLOCK(cdev_lock); static struct kobject *cdev_get(struct cdev *p) { struct module *owner = p->owner; struct kobject *kobj; if (!try_module_get(owner)) return NULL; kobj = kobject_get_unless_zero(&p->kobj); if (!kobj) module_put(owner); return kobj; } void cdev_put(struct cdev *p) { if (p) { struct module *owner = p->owner; kobject_put(&p->kobj); module_put(owner); } } /* * Called every time a character special file is opened */ static int chrdev_open(struct inode *inode, struct file *filp) { const struct file_operations *fops; struct cdev *p; struct cdev *new = NULL; int ret = 0; spin_lock(&cdev_lock); p = inode->i_cdev; if (!p) { struct kobject *kobj; int idx; spin_unlock(&cdev_lock); kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); if (!kobj) return -ENXIO; new = container_of(kobj, struct cdev, kobj); spin_lock(&cdev_lock); /* Check i_cdev again in case somebody beat us to it while we dropped the lock. */ p = inode->i_cdev; if (!p) { inode->i_cdev = p = new; list_add(&inode->i_devices, &p->list); new = NULL; } else if (!cdev_get(p)) ret = -ENXIO; } else if (!cdev_get(p)) ret = -ENXIO; spin_unlock(&cdev_lock); cdev_put(new); if (ret) return ret; ret = -ENXIO; fops = fops_get(p->ops); if (!fops) goto out_cdev_put; replace_fops(filp, fops); if (filp->f_op->open) { ret = filp->f_op->open(inode, filp); if (ret) goto out_cdev_put; } return 0; out_cdev_put: cdev_put(p); return ret; } void cd_forget(struct inode *inode) { spin_lock(&cdev_lock); list_del_init(&inode->i_devices); inode->i_cdev = NULL; inode->i_mapping = &inode->i_data; spin_unlock(&cdev_lock); } static void cdev_purge(struct cdev *cdev) { spin_lock(&cdev_lock); while (!list_empty(&cdev->list)) { struct inode *inode; inode = container_of(cdev->list.next, struct inode, i_devices); list_del_init(&inode->i_devices); inode->i_cdev = NULL; } spin_unlock(&cdev_lock); } /* * Dummy default file-operations: the only thing this does * is contain the open that then fills in the correct operations * depending on the special file... */ const struct file_operations def_chr_fops = { .open = chrdev_open, .llseek = noop_llseek, }; static struct kobject *exact_match(dev_t dev, int *part, void *data) { struct cdev *p = data; return &p->kobj; } static int exact_lock(dev_t dev, void *data) { struct cdev *p = data; return cdev_get(p) ? 0 : -1; } /** * cdev_add() - add a char device to the system * @p: the cdev structure for the device * @dev: the first device number for which this device is responsible * @count: the number of consecutive minor numbers corresponding to this * device * * cdev_add() adds the device represented by @p to the system, making it * live immediately. A negative error code is returned on failure. */ int cdev_add(struct cdev *p, dev_t dev, unsigned count) { int error; p->dev = dev; p->count = count; if (WARN_ON(dev == WHITEOUT_DEV)) { error = -EBUSY; goto err; } error = kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p); if (error) goto err; kobject_get(p->kobj.parent); return 0; err: