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 vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf) 41 { 42 unsigned long offset; 43 struct page *page; 44 struct fb_info *info = vmf->vma->vm_private_data; 45 46 offset = vmf->pgoff << PAGE_SHIFT; 47 if (offset >= info->fix.smem_len) 48 return VM_FAULT_SIGBUS; 49 50 page = fb_deferred_io_page(info, offset); 51 if (!page) 52 return VM_FAULT_SIGBUS; 53 54 get_page(page); 55 56 if (vmf->vma->vm_file) 57 page->mapping = vmf->vma->vm_file->f_mapping; 58 else 59 printk(KERN_ERR "no mapping available\n"); 60 61 BUG_ON(!page->mapping); 62 INIT_LIST_HEAD(&page->lru); 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 = file_write_and_wait_range(file, 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 inode_lock(inode); 82 /* Kill off the delayed work */ 83 cancel_delayed_work_sync(&info->deferred_work); 84 85 /* Run it immediately */ 86 schedule_delayed_work(&info->deferred_work, 0); 87 inode_unlock(inode); 88 89 return 0; 90 } 91 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); 92 93 /* vm_ops->page_mkwrite handler */ 94 static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) 95 { 96 struct page *page = vmf->page; 97 struct fb_info *info = vmf->vma->vm_private_data; 98 struct fb_deferred_io *fbdefio = info->fbdefio; 99 struct list_head *pos = &fbdefio->pagelist; 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(vmf->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 /* 127 * This check is to catch the case where a new process could start 128 * writing to the same page through a new PTE. This new access 129 * can cause a call to .page_mkwrite even if the original process' 130 * PTE is marked writable. 131 * 132 * TODO: The lru field is owned by the page cache; hence the name. 133 * We dequeue in fb_deferred_io_work() after flushing the 134 * page's content into video memory. Instead of lru, fbdefio 135 * should have it's own field. 136 */ 137 if (!list_empty(&page->lru)) 138 goto page_already_added; 139 140 if (unlikely(fbdefio->sort_pagelist)) { 141 /* 142 * We loop through the pagelist before adding in order to 143 * keep the pagelist sorted. This has significant overhead 144 * of O(n^2) with n being the number of written pages. If 145 * possible, drivers should try to work with unsorted page 146 * lists instead. 147 */ 148 struct page *cur; 149 150 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 151 if (cur->index > page->index) 152 break; 153 } 154 pos = &cur->lru; 155 } 156 157 list_add_tail(&page->lru, pos); 158 159 page_already_added: 160 mutex_unlock(&fbdefio->lock); 161 162 /* come back after delay to process the deferred IO */ 163 schedule_delayed_work(&info->deferred_work, fbdefio->delay); 164 return VM_FAULT_LOCKED; 165 } 166 167 static const struct vm_operations_struct fb_deferred_io_vm_ops = { 168 .fault = fb_deferred_io_fault, 169 .page_mkwrite = fb_deferred_io_mkwrite, 170 }; 171 172 static int fb_deferred_io_set_page_dirty(struct page *page) 173 { 174 if (!PageDirty(page)) 175 SetPageDirty(page); 176 return 0; 177 } 178 179 static const struct address_space_operations fb_deferred_io_aops = { 180 .set_page_dirty = fb_deferred_io_set_page_dirty, 181 }; 182 183 int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) 184 { 185 vma->vm_ops = &fb_deferred_io_vm_ops; 186 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; 187 if (!(info->flags & FBINFO_VIRTFB)) 188 vma->vm_flags |= VM_IO; 189 vma->vm_private_data = info; 190 return 0; 191 } 192 193 /* workqueue callback */ 194 static void fb_deferred_io_work(struct work_struct *work) 195 { 196 struct fb_info *info = container_of(work, struct fb_info, 197 deferred_work.work); 198 struct list_head *node, *next; 199 struct page *cur; 200 struct fb_deferred_io *fbdefio = info->fbdefio; 201 202 /* here we mkclean the pages, then do all deferred IO */ 203 mutex_lock(&fbdefio->lock); 204 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 205 lock_page(cur); 206 page_mkclean(cur); 207 unlock_page(cur); 208 } 209 210 /* driver's callback with pagelist */ 211 fbdefio->deferred_io(info, &fbdefio->pagelist); 212 213 /* clear the list */ 214 list_for_each_safe(node, next, &fbdefio->pagelist) { 215 list_del_init(node); 216 } 217 mutex_unlock(&fbdefio->lock); 218 } 219 220 void fb_deferred_io_init(struct fb_info *info) 221 { 222 struct fb_deferred_io *fbdefio = info->fbdefio; 223 224 BUG_ON(!fbdefio); 225 mutex_init(&fbdefio->lock); 226 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work); 227 INIT_LIST_HEAD(&fbdefio->pagelist); 228 if (fbdefio->delay == 0) /* set a default of 1 s */ 229 fbdefio->delay = HZ; 230 } 231 EXPORT_SYMBOL_GPL(fb_deferred_io_init); 232 233 void fb_deferred_io_open(struct fb_info *info, 234 struct inode *inode, 235 struct file *file) 236 { 237 file->f_mapping->a_ops = &fb_deferred_io_aops; 238 } 239 EXPORT_SYMBOL_GPL(fb_deferred_io_open); 240 241 void fb_deferred_io_cleanup(struct fb_info *info) 242 { 243 struct fb_deferred_io *fbdefio = info->fbdefio; 244 struct page *page; 245 int i; 246 247 BUG_ON(!fbdefio); 248 cancel_delayed_work_sync(&info->deferred_work); 249 250 /* clear out the mapping that we setup */ 251 for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) { 252 page = fb_deferred_io_page(info, i); 253 page->mapping = NULL; 254 } 255 256 mutex_destroy(&fbdefio->lock); 257 } 258 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup); 259