#define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1)
#define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN)
-/*
- * ashmem_area - anonymous shared memory area
- * Lifecycle: From our parent file's open() until its release()
- * Locking: Protected by `ashmem_mutex'
- * Big Note: Mappings do NOT pin this structure; it dies on close()
+/**
+ * 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]; /* optional name in /proc/pid/maps */
- struct list_head unpinned_list; /* list of all ashmem areas */
- struct file *file; /* the shmem-based backing file */
- size_t size; /* size of the mapping, in bytes */
- unsigned long prot_mask; /* allowed prot bits, as vm_flags */
+ char name[ASHMEM_FULL_NAME_LEN];
+ struct list_head unpinned_list;
+ struct file *file;
+ size_t size;
+ unsigned long prot_mask;
};
-/*
- * ashmem_range - represents an interval of unpinned (evictable) pages
- * Lifecycle: From unpin to pin
- * Locking: Protected by `ashmem_mutex'
+/**
+ * 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; /* entry in LRU list */
- struct list_head unpinned; /* entry in its area's unpinned list */
- struct ashmem_area *asma; /* associated area */
- size_t pgstart; /* starting page, inclusive */
- size_t pgend; /* ending page, inclusive */
- unsigned int purged; /* ASHMEM_NOT or ASHMEM_WAS_PURGED */
+ 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);
-/* Count of pages on our LRU list, protected by ashmem_mutex */
+/**
+ * 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
#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 - allocate and initialize a new ashmem_range structure
+/**
+ * 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)
*
- * 'asma' - associated ashmem_area
- * 'prev_range' - the previous ashmem_range in the sorted asma->unpinned list
- * 'purged' - initial purge value (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED)
- * 'start' - starting page, inclusive
- * 'end' - ending page, inclusive
+ * This function is protected by ashmem_mutex.
*
- * Caller must hold 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,
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);
kmem_cache_free(ashmem_range_cachep, range);
}
-/*
- * range_shrink - shrinks a 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
*
- * Caller must hold ashmem_mutex.
+ * 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)
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;
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;
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)
{
.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);
}
projects / ~andy / linux / blobdiff