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1 | /* |
2 | * linux/drivers/video/fb_defio.c |
3 | * |
4 | * Copyright (C) 2006 Jaya Kumar |
5 | * |
6 | * This file is subject to the terms and conditions of the GNU General Public |
7 | * License. See the file COPYING in the main directory of this archive |
8 | * for more details. |
9 | */ |
10 | |
11 | #include <linux/module.h> |
12 | #include <linux/kernel.h> |
13 | #include <linux/errno.h> |
14 | #include <linux/string.h> |
15 | #include <linux/mm.h> |
16 | #include <linux/vmalloc.h> |
17 | #include <linux/delay.h> |
18 | #include <linux/interrupt.h> |
19 | #include <linux/fb.h> |
20 | #include <linux/list.h> |
21 | |
22 | /* to support deferred IO */ |
23 | #include <linux/rmap.h> |
24 | #include <linux/pagemap.h> |
25 | |
26 | static struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs) |
27 | { |
28 | void *screen_base = (void __force *) info->screen_base; |
29 | struct page *page; |
30 | |
31 | if (is_vmalloc_addr(screen_base + offs)) |
32 | page = vmalloc_to_page(screen_base + offs); |
33 | else |
34 | page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT); |
35 | |
36 | return page; |
37 | } |
38 | |
39 | /* this is to find and return the vmalloc-ed fb pages */ |
40 | static int fb_deferred_io_fault(struct vm_area_struct *vma, |
41 | struct vm_fault *vmf) |
42 | { |
43 | unsigned long offset; |
44 | struct page *page; |
45 | struct fb_info *info = vma->vm_private_data; |
46 | |
47 | offset = vmf->pgoff << PAGE_SHIFT; |
48 | if (offset >= info->fix.smem_len) |
49 | return VM_FAULT_SIGBUS; |
50 | |
51 | page = fb_deferred_io_page(info, offset); |
52 | if (!page) |
53 | return VM_FAULT_SIGBUS; |
54 | |
55 | get_page(page); |
56 | |
57 | if (vma->vm_file) |
58 | page->mapping = vma->vm_file->f_mapping; |
59 | else |
60 | printk(KERN_ERR "no mapping available\n"); |
61 | |
62 | BUG_ON(!page->mapping); |
63 | page->index = vmf->pgoff; |
64 | |
65 | vmf->page = page; |
66 | return 0; |
67 | } |
68 | |
69 | int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync) |
70 | { |
71 | struct fb_info *info = file->private_data; |
72 | struct inode *inode = file_inode(file); |
73 | int err = filemap_write_and_wait_range(inode->i_mapping, start, end); |
74 | if (err) |
75 | return err; |
76 | |
77 | /* Skip if deferred io is compiled-in but disabled on this fbdev */ |
78 | if (!info->fbdefio) |
79 | return 0; |
80 | |
81 | mutex_lock(&inode->i_mutex); |
82 | /* Kill off the delayed work */ |
83 | cancel_delayed_work_sync(&info->deferred_work); |
84 | |
85 | /* Run it immediately */ |
86 | err = schedule_delayed_work(&info->deferred_work, 0); |
87 | mutex_unlock(&inode->i_mutex); |
88 | return err; |
89 | } |
90 | EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); |
91 | |
92 | /* vm_ops->page_mkwrite handler */ |
93 | static int fb_deferred_io_mkwrite(struct vm_area_struct *vma, |
94 | struct vm_fault *vmf) |
95 | { |
96 | struct page *page = vmf->page; |
97 | struct fb_info *info = vma->vm_private_data; |
98 | struct fb_deferred_io *fbdefio = info->fbdefio; |
99 | struct page *cur; |
100 | |
101 | /* this is a callback we get when userspace first tries to |
102 | write to the page. we schedule a workqueue. that workqueue |
103 | will eventually mkclean the touched pages and execute the |
104 | deferred framebuffer IO. then if userspace touches a page |
105 | again, we repeat the same scheme */ |
106 | |
107 | file_update_time(vma->vm_file); |
108 | |
109 | /* protect against the workqueue changing the page list */ |
110 | mutex_lock(&fbdefio->lock); |
111 | |
112 | /* first write in this cycle, notify the driver */ |
113 | if (fbdefio->first_io && list_empty(&fbdefio->pagelist)) |
114 | fbdefio->first_io(info); |
115 | |
116 | /* |
117 | * We want the page to remain locked from ->page_mkwrite until |
118 | * the PTE is marked dirty to avoid page_mkclean() being called |
119 | * before the PTE is updated, which would leave the page ignored |
120 | * by defio. |
121 | * Do this by locking the page here and informing the caller |
122 | * about it with VM_FAULT_LOCKED. |
123 | */ |
124 | lock_page(page); |
125 | |
126 | /* we loop through the pagelist before adding in order |
127 | to keep the pagelist sorted */ |
128 | list_for_each_entry(cur, &fbdefio->pagelist, lru) { |
129 | /* this check is to catch the case where a new |
130 | process could start writing to the same page |
131 | through a new pte. this new access can cause the |
132 | mkwrite even when the original ps's pte is marked |
133 | writable */ |
134 | if (unlikely(cur == page)) |
135 | goto page_already_added; |
136 | else if (cur->index > page->index) |
137 | break; |
138 | } |
139 | |
140 | list_add_tail(&page->lru, &cur->lru); |
141 | |
142 | page_already_added: |
143 | mutex_unlock(&fbdefio->lock); |
144 | |
145 | /* come back after delay to process the deferred IO */ |
146 | schedule_delayed_work(&info->deferred_work, fbdefio->delay); |
147 | return VM_FAULT_LOCKED; |
148 | } |
149 | |
150 | static const struct vm_operations_struct fb_deferred_io_vm_ops = { |
151 | .fault = fb_deferred_io_fault, |
152 | .page_mkwrite = fb_deferred_io_mkwrite, |
153 | }; |
154 | |
155 | static int fb_deferred_io_set_page_dirty(struct page *page) |
156 | { |
157 | if (!PageDirty(page)) |
158 | SetPageDirty(page); |
159 | return 0; |
160 | } |
161 | |
162 | static const struct address_space_operations fb_deferred_io_aops = { |
163 | .set_page_dirty = fb_deferred_io_set_page_dirty, |
164 | }; |
165 | |
166 | static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) |
167 | { |
168 | vma->vm_ops = &fb_deferred_io_vm_ops; |
169 | vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; |
170 | if (!(info->flags & FBINFO_VIRTFB)) |
171 | vma->vm_flags |= VM_IO; |
172 | vma->vm_private_data = info; |
173 | return 0; |
174 | } |
175 | |
176 | /* workqueue callback */ |
177 | static void fb_deferred_io_work(struct work_struct *work) |
178 | { |
179 | struct fb_info *info = container_of(work, struct fb_info, |
180 | deferred_work.work); |
181 | struct list_head *node, *next; |
182 | struct page *cur; |
183 | struct fb_deferred_io *fbdefio = info->fbdefio; |
184 | |
185 | /* here we mkclean the pages, then do all deferred IO */ |
186 | mutex_lock(&fbdefio->lock); |
187 | list_for_each_entry(cur, &fbdefio->pagelist, lru) { |
188 | lock_page(cur); |
189 | page_mkclean(cur); |
190 | unlock_page(cur); |
191 | } |
192 | |
193 | /* driver's callback with pagelist */ |
194 | fbdefio->deferred_io(info, &fbdefio->pagelist); |
195 | |
196 | /* clear the list */ |
197 | list_for_each_safe(node, next, &fbdefio->pagelist) { |
198 | list_del(node); |
199 | } |
200 | mutex_unlock(&fbdefio->lock); |
201 | } |
202 | |
203 | void fb_deferred_io_init(struct fb_info *info) |
204 | { |
205 | struct fb_deferred_io *fbdefio = info->fbdefio; |
206 | |
207 | BUG_ON(!fbdefio); |
208 | mutex_init(&fbdefio->lock); |
209 | info->fbops->fb_mmap = fb_deferred_io_mmap; |
210 | INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work); |
211 | INIT_LIST_HEAD(&fbdefio->pagelist); |
212 | if (fbdefio->delay == 0) /* set a default of 1 s */ |
213 | fbdefio->delay = HZ; |
214 | } |
215 | EXPORT_SYMBOL_GPL(fb_deferred_io_init); |
216 | |
217 | void fb_deferred_io_open(struct fb_info *info, |
218 | struct inode *inode, |
219 | struct file *file) |
220 | { |
221 | file->f_mapping->a_ops = &fb_deferred_io_aops; |
222 | } |
223 | EXPORT_SYMBOL_GPL(fb_deferred_io_open); |
224 | |
225 | void fb_deferred_io_cleanup(struct fb_info *info) |
226 | { |
227 | struct fb_deferred_io *fbdefio = info->fbdefio; |
228 | struct page *page; |
229 | int i; |
230 | |
231 | BUG_ON(!fbdefio); |
232 | cancel_delayed_work_sync(&info->deferred_work); |
233 | |
234 | /* clear out the mapping that we setup */ |
235 | for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) { |
236 | page = fb_deferred_io_page(info, i); |
237 | page->mapping = NULL; |
238 | } |
239 | |
240 | info->fbops->fb_mmap = NULL; |
241 | mutex_destroy(&fbdefio->lock); |
242 | } |
243 | EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup); |
244 | |
245 | MODULE_LICENSE("GPL"); |
246 |
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