2 * RelayFS buffer management code.
4 * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
5 * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com)
7 * This file is released under the GPL.
10 #include <linux/module.h>
11 #include <linux/vmalloc.h>
13 #include <linux/relayfs_fs.h>
18 * close() vm_op implementation for relayfs file mapping.
20 static void relay_file_mmap_close(struct vm_area_struct *vma)
22 struct rchan_buf *buf = vma->vm_private_data;
23 buf->chan->cb->buf_unmapped(buf, vma->vm_file);
27 * nopage() vm_op implementation for relayfs file mapping.
29 static struct page *relay_buf_nopage(struct vm_area_struct *vma,
30 unsigned long address,
34 struct rchan_buf *buf = vma->vm_private_data;
35 unsigned long offset = address - vma->vm_start;
37 if (address > vma->vm_end)
38 return NOPAGE_SIGBUS; /* Disallow mremap */
42 page = vmalloc_to_page(buf->start + offset);
48 *type = VM_FAULT_MINOR;
54 * vm_ops for relay file mappings.
56 static struct vm_operations_struct relay_file_mmap_ops = {
57 .nopage = relay_buf_nopage,
58 .close = relay_file_mmap_close,
62 * relay_mmap_buf: - mmap channel buffer to process address space
63 * @buf: relay channel buffer
64 * @vma: vm_area_struct describing memory to be mapped
66 * Returns 0 if ok, negative on error
68 * Caller should already have grabbed mmap_sem.
70 int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
72 unsigned long length = vma->vm_end - vma->vm_start;
73 struct file *filp = vma->vm_file;
78 if (length != (unsigned long)buf->chan->alloc_size)
81 vma->vm_ops = &relay_file_mmap_ops;
82 vma->vm_private_data = buf;
83 buf->chan->cb->buf_mapped(buf, filp);
89 * relay_alloc_buf - allocate a channel buffer
90 * @buf: the buffer struct
91 * @size: total size of the buffer
93 * Returns a pointer to the resulting buffer, NULL if unsuccessful
95 static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size)
98 unsigned int i, j, n_pages;
100 size = PAGE_ALIGN(size);
101 n_pages = size >> PAGE_SHIFT;
103 buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
104 if (!buf->page_array)
107 for (i = 0; i < n_pages; i++) {
108 buf->page_array[i] = alloc_page(GFP_KERNEL);
109 if (unlikely(!buf->page_array[i]))
112 mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL);
116 memset(mem, 0, size);
117 buf->page_count = n_pages;
121 for (j = 0; j < i; j++)
122 __free_page(buf->page_array[j]);
123 kfree(buf->page_array);
128 * relay_create_buf - allocate and initialize a channel buffer
129 * @alloc_size: size of the buffer to allocate
130 * @n_subbufs: number of sub-buffers in the channel
132 * Returns channel buffer if successful, NULL otherwise
134 struct rchan_buf *relay_create_buf(struct rchan *chan)
136 struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL);
140 buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
144 buf->start = relay_alloc_buf(buf, chan->alloc_size);
149 kref_get(&buf->chan->kref);
159 * relay_destroy_buf - destroy an rchan_buf struct and associated buffer
160 * @buf: the buffer struct
162 void relay_destroy_buf(struct rchan_buf *buf)
164 struct rchan *chan = buf->chan;
167 if (likely(buf->start)) {
169 for (i = 0; i < buf->page_count; i++)
170 __free_page(buf->page_array[i]);
171 kfree(buf->page_array);
175 kref_put(&chan->kref, relay_destroy_channel);
179 * relay_remove_buf - remove a channel buffer
181 * Removes the file from the relayfs fileystem, which also frees the
182 * rchan_buf_struct and the channel buffer. Should only be called from
185 void relay_remove_buf(struct kref *kref)
187 struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
188 relayfs_remove(buf->dentry);