diff options
Diffstat (limited to 'drivers/staging/android/ashmem.c')
| -rw-r--r-- | drivers/staging/android/ashmem.c | 886 |
1 files changed, 886 insertions, 0 deletions
diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c new file mode 100644 index 00000000000..713a9722678 --- /dev/null +++ b/drivers/staging/android/ashmem.c @@ -0,0 +1,886 @@ +/* mm/ashmem.c + * + * Anonymous Shared Memory Subsystem, ashmem + * + * Copyright (C) 2008 Google, Inc. + * + * Robert Love <rlove@google.com> + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * 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. + */ + +#define pr_fmt(fmt) "ashmem: " fmt + +#include <linux/module.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/falloc.h> +#include <linux/miscdevice.h> +#include <linux/security.h> +#include <linux/mm.h> +#include <linux/mman.h> +#include <linux/uaccess.h> +#include <linux/personality.h> +#include <linux/bitops.h> +#include <linux/mutex.h> +#include <linux/shmem_fs.h> +#include "ashmem.h" + +#define ASHMEM_NAME_PREFIX "dev/ashmem/" +#define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1) +#define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN) + +/** + * struct ashmem_area - The anonymous shared memory area + * @name: The optional name in /proc/pid/maps + * @unpinned_list: The list of all ashmem areas + * @file: The shmem-based backing file + * @size: The size of the mapping, in bytes + * @prot_masks: The allowed protection bits, as vm_flags + * + * The lifecycle of this structure is from our parent file's open() until + * its release(). It is also protected by 'ashmem_mutex' + * + * Warning: Mappings do NOT pin this structure; It dies on close() + */ +struct ashmem_area { + char name[ASHMEM_FULL_NAME_LEN]; + struct list_head unpinned_list; + struct file *file; + size_t size; + unsigned long prot_mask; +}; + +/** + * struct ashmem_range - A range of unpinned/evictable pages + * @lru: The entry in the LRU list + * @unpinned: The entry in its area's unpinned list + * @asma: The associated anonymous shared memory area. + * @pgstart: The starting page (inclusive) + * @pgend: The ending page (inclusive) + * @purged: The purge status (ASHMEM_NOT or ASHMEM_WAS_PURGED) + * + * The lifecycle of this structure is from unpin to pin. + * It is protected by 'ashmem_mutex' + */ +struct ashmem_range { + struct list_head lru; + struct list_head unpinned; + struct ashmem_area *asma; + size_t pgstart; + size_t pgend; + unsigned int purged; +}; + +/* LRU list of unpinned pages, protected by ashmem_mutex */ +static LIST_HEAD(ashmem_lru_list); + +/** + * long lru_count - The count of pages on our LRU list. + * + * This is protected by ashmem_mutex. + */ +static unsigned long lru_count; + +/** + * ashmem_mutex - protects the list of and each individual ashmem_area + * + * Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem + */ +static DEFINE_MUTEX(ashmem_mutex); + +static struct kmem_cache *ashmem_area_cachep __read_mostly; +static struct kmem_cache *ashmem_range_cachep __read_mostly; + +#define range_size(range) \ + ((range)->pgend - (range)->pgstart + 1) + +#define range_on_lru(range) \ + ((range)->purged == ASHMEM_NOT_PURGED) + +#define page_range_subsumes_range(range, start, end) \ + (((range)->pgstart >= (start)) && ((range)->pgend <= (end))) + +#define page_range_subsumed_by_range(range, start, end) \ + (((range)->pgstart <= (start)) && ((range)->pgend >= (end))) + +#define page_in_range(range, page) \ + (((range)->pgstart <= (page)) && ((range)->pgend >= (page))) + +#define page_range_in_range(range, start, end) \ + (page_in_range(range, start) || page_in_range(range, end) || \ + page_range_subsumes_range(range, start, end)) + +#define range_before_page(range, page) \ + ((range)->pgend < (page)) + +#define PROT_MASK (PROT_EXEC | PROT_READ | PROT_WRITE) + +/** + * lru_add() - Adds a range of memory to the LRU list + * @range: The memory range being added. + * + * The range is first added to the end (tail) of the LRU list. + * After this, the size of the range is added to @lru_count + */ +static inline void lru_add(struct ashmem_range *range) +{ + list_add_tail(&range->lru, &ashmem_lru_list); + lru_count += range_size(range); +} + +/** + * lru_del() - Removes a range of memory from the LRU list + * @range: The memory range being removed + * + * The range is first deleted from the LRU list. + * After this, the size of the range is removed from @lru_count + */ +static inline void lru_del(struct ashmem_range *range) +{ + list_del(&range->lru); + lru_count -= range_size(range); +} + +/** + * range_alloc() - Allocates and initializes a new ashmem_range structure + * @asma: The associated ashmem_area + * @prev_range: The previous ashmem_range in the sorted asma->unpinned list + * @purged: Initial purge status (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED) + * @start: The starting page (inclusive) + * @end: The ending page (inclusive) + * + * This function is protected by ashmem_mutex. + * + * Return: 0 if successful, or -ENOMEM if there is an error + */ +static int range_alloc(struct ashmem_area *asma, + struct ashmem_range *prev_range, unsigned int purged, + size_t start, size_t end) +{ + struct ashmem_range *range; + + range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL); + if (unlikely(!range)) + return -ENOMEM; + + range->asma = asma; + range->pgstart = start; + range->pgend = end; + range->purged = purged; + + list_add_tail(&range->unpinned, &prev_range->unpinned); + + if (range_on_lru(range)) + lru_add(range); + + return 0; +} + +/** + * range_del() - Deletes and dealloctes an ashmem_range structure + * @range: The associated ashmem_range that has previously been allocated + */ +static void range_del(struct ashmem_range *range) +{ + list_del(&range->unpinned); + if (range_on_lru(range)) + lru_del(range); + kmem_cache_free(ashmem_range_cachep, range); +} + +/** + * range_shrink() - Shrinks an ashmem_range + * @range: The associated ashmem_range being shrunk + * @start: The starting byte of the new range + * @end: The ending byte of the new range + * + * This does not modify the data inside the existing range in any way - It + * simply shrinks the boundaries of the range. + * + * Theoretically, with a little tweaking, this could eventually be changed + * to range_resize, and expand the lru_count if the new range is larger. + */ +static inline void range_shrink(struct ashmem_range *range, + size_t start, size_t end) +{ + size_t pre = range_size(range); + + range->pgstart = start; + range->pgend = end; + + if (range_on_lru(range)) + lru_count -= pre - range_size(range); +} + +/** + * ashmem_open() - Opens an Anonymous Shared Memory structure + * @inode: The backing file's index node(?) + * @file: The backing file + * + * Please note that the ashmem_area is not returned by this function - It is + * instead written to "file->private_data". + * + * Return: 0 if successful, or another code if unsuccessful. + */ +static int ashmem_open(struct inode *inode, struct file *file) +{ + struct ashmem_area *asma; + int ret; + + ret = generic_file_open(inode, file); + if (unlikely(ret)) + return ret; + + asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL); + if (unlikely(!asma)) + return -ENOMEM; + + INIT_LIST_HEAD(&asma->unpinned_list); + memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN); + asma->prot_mask = PROT_MASK; + file->private_data = asma; + + return 0; +} + +/** + * ashmem_release() - Releases an Anonymous Shared Memory structure + * @ignored: The backing file's Index Node(?) - It is ignored here. + * @file: The backing file + * + * Return: 0 if successful. If it is anything else, go have a coffee and + * try again. + */ +static int ashmem_release(struct inode *ignored, struct file *file) +{ + struct ashmem_area *asma = file->private_data; + struct ashmem_range *range, *next; + + mutex_lock(&ashmem_mutex); + list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) + range_del(range); + mutex_unlock(&ashmem_mutex); + + if (asma->file) + fput(asma->file); + kmem_cache_free(ashmem_area_cachep, asma); + + return 0; +} + +/** + * ashmem_read() - Reads a set of bytes from an Ashmem-enabled file + * @file: The associated backing file. + * @buf: The buffer of data being written to + * @len: The number of bytes being read + * @pos: The position of the first byte to read. + * + * Return: 0 if successful, or another return code if not. + */ +static ssize_t ashmem_read(struct file *file, char __user *buf, + size_t len, loff_t *pos) +{ + struct ashmem_area *asma = file->private_data; + int ret = 0; + + mutex_lock(&ashmem_mutex); + + /* If size is not set, or set to 0, always return EOF. */ + if (asma->size == 0) + goto out_unlock; + + if (!asma->file) { + ret = -EBADF; + goto out_unlock; + } + + mutex_unlock(&ashmem_mutex); + + /* + * asma and asma->file are used outside the lock here. We assume + * once asma->file is set it will never be changed, and will not + * be destroyed until all references to the file are dropped and + * ashmem_release is called. + */ + ret = asma->file->f_op->read(asma->file, buf, len, pos); + if (ret >= 0) { + /** Update backing file pos, since f_ops->read() doesn't */ + asma->file->f_pos = *pos; + } + return ret; + +out_unlock: + mutex_unlock(&ashmem_mutex); + return ret; +} + +static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin) +{ + struct ashmem_area *asma = file->private_data; + int ret; + + mutex_lock(&ashmem_mutex); + + if (asma->size == 0) { + ret = -EINVAL; + goto out; + } + + if (!asma->file) { + ret = -EBADF; + goto out; + } + + ret = asma->file->f_op->llseek(asma->file, offset, origin); + if (ret < 0) + goto out; + + /** Copy f_pos from backing file, since f_ops->llseek() sets it */ + file->f_pos = asma->file->f_pos; + +out: + mutex_unlock(&ashmem_mutex); + return ret; +} + +static inline vm_flags_t calc_vm_may_flags(unsigned long prot) +{ + return _calc_vm_trans(prot, PROT_READ, VM_MAYREAD) | + _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) | + _calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC); +} + +static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct ashmem_area *asma = file->private_data; + int ret = 0; + + mutex_lock(&ashmem_mutex); + + /* user needs to SET_SIZE before mapping */ + if (unlikely(!asma->size)) { + ret = -EINVAL; + goto out; + } + + /* requested protection bits must match our allowed protection mask */ + if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask)) & + calc_vm_prot_bits(PROT_MASK))) { + ret = -EPERM; + goto out; + } + vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask); + + if (!asma->file) { + char *name = ASHMEM_NAME_DEF; + struct file *vmfile; + + if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') + name = asma->name; + + /* ... and allocate the backing shmem file */ + vmfile = shmem_file_setup(name, asma->size, vma->vm_flags); + if (unlikely(IS_ERR(vmfile))) { + ret = PTR_ERR(vmfile); + goto out; + } + asma->file = vmfile; + } + get_file(asma->file); + + /* + * XXX - Reworked to use shmem_zero_setup() instead of + * shmem_set_file while we're in staging. -jstultz + */ + if (vma->vm_flags & VM_SHARED) { + ret = shmem_zero_setup(vma); + if (ret) { + fput(asma->file); + goto out; + } + } + + if (vma->vm_file) + fput(vma->vm_file); + vma->vm_file = asma->file; + +out: + mutex_unlock(&ashmem_mutex); + return ret; +} + +/* + * ashmem_shrink - our cache shrinker, called from mm/vmscan.c :: shrink_slab + * + * 'nr_to_scan' is the number of objects to scan for freeing. + * + * 'gfp_mask' is the mask of the allocation that got us into this mess. + * + * Return value is the number of objects freed or -1 if we cannot + * proceed without risk of deadlock (due to gfp_mask). + * + * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial + * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan' + * pages freed. + */ +static unsigned long +ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) +{ + struct ashmem_range *range, *next; + unsigned long freed = 0; + + /* We might recurse into filesystem code, so bail out if necessary */ + if (!(sc->gfp_mask & __GFP_FS)) + return SHRINK_STOP; + + mutex_lock(&ashmem_mutex); + list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) { + loff_t start = range->pgstart * PAGE_SIZE; + loff_t end = (range->pgend + 1) * PAGE_SIZE; + + do_fallocate(range->asma->file, + FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, + start, end - start); + range->purged = ASHMEM_WAS_PURGED; + lru_del(range); + + freed += range_size(range); + if (--sc->nr_to_scan <= 0) + break; + } + mutex_unlock(&ashmem_mutex); + return freed; +} + +static unsigned long +ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc) +{ + /* + * note that lru_count is count of pages on the lru, not a count of + * objects on the list. This means the scan function needs to return the + * number of pages freed, not the number of objects scanned. + */ + return lru_count; +} + +static struct shrinker ashmem_shrinker = { + .count_objects = ashmem_shrink_count, + .scan_objects = ashmem_shrink_scan, + /* + * XXX (dchinner): I wish people would comment on why they need on + * significant changes to the default value here + */ + .seeks = DEFAULT_SEEKS * 4, +}; + +static int set_prot_mask(struct ashmem_area *asma, unsigned long prot) +{ + int ret = 0; + + mutex_lock(&ashmem_mutex); + + /* the user can only remove, not add, protection bits */ + if (unlikely((asma->prot_mask & prot) != prot)) { + ret = -EINVAL; + goto out; + } + + /* does the application expect PROT_READ to imply PROT_EXEC? */ + if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) + prot |= PROT_EXEC; + + asma->prot_mask = prot; + +out: + mutex_unlock(&ashmem_mutex); + return ret; +} + +static int set_name(struct ashmem_area *asma, void __user *name) +{ + int len; + int ret = 0; + char local_name[ASHMEM_NAME_LEN]; + + /* + * Holding the ashmem_mutex while doing a copy_from_user might cause + * an data abort which would try to access mmap_sem. If another + * thread has invoked ashmem_mmap then it will be holding the + * semaphore and will be waiting for ashmem_mutex, there by leading to + * deadlock. We'll release the mutex and take the name to a local + * variable that does not need protection and later copy the local + * variable to the structure member with lock held. + */ + len = strncpy_from_user(local_name, name, ASHMEM_NAME_LEN); + if (len < 0) + return len; + if (len == ASHMEM_NAME_LEN) + local_name[ASHMEM_NAME_LEN - 1] = '\0'; + mutex_lock(&ashmem_mutex); + /* cannot change an existing mapping's name */ + if (unlikely(asma->file)) + ret = -EINVAL; + else + strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name); + + mutex_unlock(&ashmem_mutex); + return ret; +} + +static int get_name(struct ashmem_area *asma, void __user *name) +{ + int ret = 0; + size_t len; + /* + * Have a local variable to which we'll copy the content + * from asma with the lock held. Later we can copy this to the user + * space safely without holding any locks. So even if we proceed to + * wait for mmap_sem, it won't lead to deadlock. + */ + char local_name[ASHMEM_NAME_LEN]; + + mutex_lock(&ashmem_mutex); + if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') { + + /* + * Copying only `len', instead of ASHMEM_NAME_LEN, bytes + * prevents us from revealing one user's stack to another. + */ + len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1; + memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len); + } else { + len = sizeof(ASHMEM_NAME_DEF); + memcpy(local_name, ASHMEM_NAME_DEF, len); + } + mutex_unlock(&ashmem_mutex); + + /* + * Now we are just copying from the stack variable to userland + * No lock held + */ + if (unlikely(copy_to_user(name, local_name, len))) + ret = -EFAULT; + return ret; +} + +/* + * ashmem_pin - pin the given ashmem region, returning whether it was + * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED). + * + * Caller must hold ashmem_mutex. + */ +static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend) +{ + struct ashmem_range *range, *next; + int ret = ASHMEM_NOT_PURGED; + + list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { + /* moved past last applicable page; we can short circuit */ + if (range_before_page(range, pgstart)) + break; + + /* + * The user can ask us to pin pages that span multiple ranges, + * or to pin pages that aren't even unpinned, so this is messy. + * + * Four cases: + * 1. The requested range subsumes an existing range, so we + * just remove the entire matching range. + * 2. The requested range overlaps the start of an existing + * range, so we just update that range. + * 3. The requested range overlaps the end of an existing + * range, so we just update that range. + * 4. The requested range punches a hole in an existing range, + * so we have to update one side of the range and then + * create a new range for the other side. + */ + if (page_range_in_range(range, pgstart, pgend)) { + ret |= range->purged; + + /* Case #1: Easy. Just nuke the whole thing. */ + if (page_range_subsumes_range(range, pgstart, pgend)) { + range_del(range); + continue; + } + + /* Case #2: We overlap from the start, so adjust it */ + if (range->pgstart >= pgstart) { + range_shrink(range, pgend + 1, range->pgend); + continue; + } + + /* Case #3: We overlap from the rear, so adjust it */ + if (range->pgend <= pgend) { + range_shrink(range, range->pgstart, pgstart-1); + continue; + } + + /* + * Case #4: We eat a chunk out of the middle. A bit + * more complicated, we allocate a new range for the + * second half and adjust the first chunk's endpoint. + */ + range_alloc(asma, range, range->purged, + pgend + 1, range->pgend); + range_shrink(range, range->pgstart, pgstart - 1); + break; + } + } + + return ret; +} + +/* + * ashmem_unpin - unpin the given range of pages. Returns zero on success. + * + * Caller must hold ashmem_mutex. + */ +static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend) +{ + struct ashmem_range *range, *next; + unsigned int purged = ASHMEM_NOT_PURGED; + +restart: + list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { + /* short circuit: this is our insertion point */ + if (range_before_page(range, pgstart)) + break; + + /* + * The user can ask us to unpin pages that are already entirely + * or partially pinned. We handle those two cases here. + */ + if (page_range_subsumed_by_range(range, pgstart, pgend)) + return 0; + if (page_range_in_range(range, pgstart, pgend)) { + pgstart = min_t(size_t, range->pgstart, pgstart), + pgend = max_t(size_t, range->pgend, pgend); + purged |= range->purged; + range_del(range); + goto restart; + } + } + + return range_alloc(asma, range, purged, pgstart, pgend); +} + +/* + * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the + * given interval are unpinned and ASHMEM_IS_PINNED otherwise. + * + * Caller must hold ashmem_mutex. + */ +static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart, + size_t pgend) +{ + struct ashmem_range *range; + int ret = ASHMEM_IS_PINNED; + + list_for_each_entry(range, &asma->unpinned_list, unpinned) { + if (range_before_page(range, pgstart)) + break; + if (page_range_in_range(range, pgstart, pgend)) { + ret = ASHMEM_IS_UNPINNED; + break; + } + } + + return ret; +} + +static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd, + void __user *p) +{ + struct ashmem_pin pin; + size_t pgstart, pgend; + int ret = -EINVAL; + + if (unlikely(!asma->file)) + return -EINVAL; + + if (unlikely(copy_from_user(&pin, p, sizeof(pin)))) + return -EFAULT; + + /* per custom, you can pass zero for len to mean "everything onward" */ + if (!pin.len) + pin.len = PAGE_ALIGN(asma->size) - pin.offset; + + if (unlikely((pin.offset | pin.len) & ~PAGE_MASK)) + return -EINVAL; + + if (unlikely(((__u32) -1) - pin.offset < pin.len)) + return -EINVAL; + + if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len)) + return -EINVAL; + + pgstart = pin.offset / PAGE_SIZE; + pgend = pgstart + (pin.len / PAGE_SIZE) - 1; + + mutex_lock(&ashmem_mutex); + + switch (cmd) { + case ASHMEM_PIN: + ret = ashmem_pin(asma, pgstart, pgend); + break; + case ASHMEM_UNPIN: + ret = ashmem_unpin(asma, pgstart, pgend); + break; + case ASHMEM_GET_PIN_STATUS: + ret = ashmem_get_pin_status(asma, pgstart, pgend); + break; + } + + mutex_unlock(&ashmem_mutex); + + return ret; +} + +static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct ashmem_area *asma = file->private_data; + long ret = -ENOTTY; + + switch (cmd) { + case ASHMEM_SET_NAME: + ret = set_name(asma, (void __user *) arg); + break; + case ASHMEM_GET_NAME: + ret = get_name(asma, (void __user *) arg); + break; + case ASHMEM_SET_SIZE: + ret = -EINVAL; + if (!asma->file) { + ret = 0; + asma->size = (size_t) arg; + } + break; + case ASHMEM_GET_SIZE: + ret = asma->size; + break; + case ASHMEM_SET_PROT_MASK: + ret = set_prot_mask(asma, arg); + break; + case ASHMEM_GET_PROT_MASK: + ret = asma->prot_mask; + break; + case ASHMEM_PIN: + case ASHMEM_UNPIN: + case ASHMEM_GET_PIN_STATUS: + ret = ashmem_pin_unpin(asma, cmd, (void __user *) arg); + break; + case ASHMEM_PURGE_ALL_CACHES: + ret = -EPERM; + if (capable(CAP_SYS_ADMIN)) { + struct shrink_control sc = { + .gfp_mask = GFP_KERNEL, + .nr_to_scan = LONG_MAX, + }; + ret = ashmem_shrink_count(&ashmem_shrinker, &sc); + nodes_setall(sc.nodes_to_scan); + ashmem_shrink_scan(&ashmem_shrinker, &sc); + } + break; + } + + return ret; +} + +/* support of 32bit userspace on 64bit platforms */ +#ifdef CONFIG_COMPAT +static long compat_ashmem_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + + switch (cmd) { + case COMPAT_ASHMEM_SET_SIZE: + cmd = ASHMEM_SET_SIZE; + break; + case COMPAT_ASHMEM_SET_PROT_MASK: + cmd = ASHMEM_SET_PROT_MASK; + break; + } + return ashmem_ioctl(file, cmd, arg); +} +#endif + +static const struct file_operations ashmem_fops = { + .owner = THIS_MODULE, + .open = ashmem_open, + .release = ashmem_release, + .read = ashmem_read, + .llseek = ashmem_llseek, + .mmap = ashmem_mmap, + .unlocked_ioctl = ashmem_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = compat_ashmem_ioctl, +#endif +}; + +static struct miscdevice ashmem_misc = { + .minor = MISC_DYNAMIC_MINOR, + .name = "ashmem", + .fops = &ashmem_fops, +}; + +static int __init ashmem_init(void) +{ + int ret; + + ashmem_area_cachep = kmem_cache_create("ashmem_area_cache", + sizeof(struct ashmem_area), + 0, 0, NULL); + if (unlikely(!ashmem_area_cachep)) { + pr_err("failed to create slab cache\n"); + return -ENOMEM; + } + + ashmem_range_cachep = kmem_cache_create("ashmem_range_cache", + sizeof(struct ashmem_range), + 0, 0, NULL); + if (unlikely(!ashmem_range_cachep)) { + pr_err("failed to create slab cache\n"); + return -ENOMEM; + } + + ret = misc_register(&ashmem_misc); + if (unlikely(ret)) { + pr_err("failed to register misc device!\n"); + return ret; + } + + register_shrinker(&ashmem_shrinker); + + pr_info("initialized\n"); + + return 0; +} + +static void __exit ashmem_exit(void) +{ + int ret; + + unregister_shrinker(&ashmem_shrinker); + + ret = misc_deregister(&ashmem_misc); + if (unlikely(ret)) + pr_err("failed to unregister misc device!\n"); + + kmem_cache_destroy(ashmem_range_cachep); + kmem_cache_destroy(ashmem_area_cachep); + + pr_info("unloaded\n"); +} + +module_init(ashmem_init); +module_exit(ashmem_exit); + +MODULE_LICENSE("GPL"); |