fb_defio.c (8950B)
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 26static 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 39static struct fb_deferred_io_pageref *fb_deferred_io_pageref_get(struct fb_info *info, 40 unsigned long offset, 41 struct page *page) 42{ 43 struct fb_deferred_io *fbdefio = info->fbdefio; 44 struct list_head *pos = &fbdefio->pagereflist; 45 unsigned long pgoff = offset >> PAGE_SHIFT; 46 struct fb_deferred_io_pageref *pageref, *cur; 47 48 if (WARN_ON_ONCE(pgoff >= info->npagerefs)) 49 return NULL; /* incorrect allocation size */ 50 51 /* 1:1 mapping between pageref and page offset */ 52 pageref = &info->pagerefs[pgoff]; 53 54 /* 55 * This check is to catch the case where a new process could start 56 * writing to the same page through a new PTE. This new access 57 * can cause a call to .page_mkwrite even if the original process' 58 * PTE is marked writable. 59 */ 60 if (!list_empty(&pageref->list)) 61 goto pageref_already_added; 62 63 pageref->page = page; 64 pageref->offset = pgoff << PAGE_SHIFT; 65 66 if (unlikely(fbdefio->sort_pagereflist)) { 67 /* 68 * We loop through the list of pagerefs before adding in 69 * order to keep the pagerefs sorted. This has significant 70 * overhead of O(n^2) with n being the number of written 71 * pages. If possible, drivers should try to work with 72 * unsorted page lists instead. 73 */ 74 list_for_each_entry(cur, &fbdefio->pagereflist, list) { 75 if (cur->offset > pageref->offset) 76 break; 77 } 78 pos = &cur->list; 79 } 80 81 list_add_tail(&pageref->list, pos); 82 83pageref_already_added: 84 return pageref; 85} 86 87static void fb_deferred_io_pageref_put(struct fb_deferred_io_pageref *pageref, 88 struct fb_info *info) 89{ 90 list_del_init(&pageref->list); 91} 92 93/* this is to find and return the vmalloc-ed fb pages */ 94static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf) 95{ 96 unsigned long offset; 97 struct page *page; 98 struct fb_info *info = vmf->vma->vm_private_data; 99 100 offset = vmf->pgoff << PAGE_SHIFT; 101 if (offset >= info->fix.smem_len) 102 return VM_FAULT_SIGBUS; 103 104 page = fb_deferred_io_page(info, offset); 105 if (!page) 106 return VM_FAULT_SIGBUS; 107 108 get_page(page); 109 110 if (vmf->vma->vm_file) 111 page->mapping = vmf->vma->vm_file->f_mapping; 112 else 113 printk(KERN_ERR "no mapping available\n"); 114 115 BUG_ON(!page->mapping); 116 page->index = vmf->pgoff; /* for page_mkclean() */ 117 118 vmf->page = page; 119 return 0; 120} 121 122int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync) 123{ 124 struct fb_info *info = file->private_data; 125 struct inode *inode = file_inode(file); 126 int err = file_write_and_wait_range(file, start, end); 127 if (err) 128 return err; 129 130 /* Skip if deferred io is compiled-in but disabled on this fbdev */ 131 if (!info->fbdefio) 132 return 0; 133 134 inode_lock(inode); 135 /* Kill off the delayed work */ 136 cancel_delayed_work_sync(&info->deferred_work); 137 138 /* Run it immediately */ 139 schedule_delayed_work(&info->deferred_work, 0); 140 inode_unlock(inode); 141 142 return 0; 143} 144EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); 145 146/* 147 * Adds a page to the dirty list. Call this from struct 148 * vm_operations_struct.page_mkwrite. 149 */ 150static vm_fault_t fb_deferred_io_track_page(struct fb_info *info, unsigned long offset, 151 struct page *page) 152{ 153 struct fb_deferred_io *fbdefio = info->fbdefio; 154 struct fb_deferred_io_pageref *pageref; 155 vm_fault_t ret; 156 157 /* protect against the workqueue changing the page list */ 158 mutex_lock(&fbdefio->lock); 159 160 /* first write in this cycle, notify the driver */ 161 if (fbdefio->first_io && list_empty(&fbdefio->pagereflist)) 162 fbdefio->first_io(info); 163 164 pageref = fb_deferred_io_pageref_get(info, offset, page); 165 if (WARN_ON_ONCE(!pageref)) { 166 ret = VM_FAULT_OOM; 167 goto err_mutex_unlock; 168 } 169 170 /* 171 * We want the page to remain locked from ->page_mkwrite until 172 * the PTE is marked dirty to avoid page_mkclean() being called 173 * before the PTE is updated, which would leave the page ignored 174 * by defio. 175 * Do this by locking the page here and informing the caller 176 * about it with VM_FAULT_LOCKED. 177 */ 178 lock_page(pageref->page); 179 180 mutex_unlock(&fbdefio->lock); 181 182 /* come back after delay to process the deferred IO */ 183 schedule_delayed_work(&info->deferred_work, fbdefio->delay); 184 return VM_FAULT_LOCKED; 185 186err_mutex_unlock: 187 mutex_unlock(&fbdefio->lock); 188 return ret; 189} 190 191/* 192 * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O 193 * @fb_info: The fbdev info structure 194 * @vmf: The VM fault 195 * 196 * This is a callback we get when userspace first tries to 197 * write to the page. We schedule a workqueue. That workqueue 198 * will eventually mkclean the touched pages and execute the 199 * deferred framebuffer IO. Then if userspace touches a page 200 * again, we repeat the same scheme. 201 * 202 * Returns: 203 * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise. 204 */ 205static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf) 206{ 207 unsigned long offset = vmf->address - vmf->vma->vm_start; 208 struct page *page = vmf->page; 209 210 file_update_time(vmf->vma->vm_file); 211 212 return fb_deferred_io_track_page(info, offset, page); 213} 214 215/* vm_ops->page_mkwrite handler */ 216static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) 217{ 218 struct fb_info *info = vmf->vma->vm_private_data; 219 220 return fb_deferred_io_page_mkwrite(info, vmf); 221} 222 223static const struct vm_operations_struct fb_deferred_io_vm_ops = { 224 .fault = fb_deferred_io_fault, 225 .page_mkwrite = fb_deferred_io_mkwrite, 226}; 227 228static const struct address_space_operations fb_deferred_io_aops = { 229 .dirty_folio = noop_dirty_folio, 230}; 231 232int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) 233{ 234 vma->vm_ops = &fb_deferred_io_vm_ops; 235 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; 236 if (!(info->flags & FBINFO_VIRTFB)) 237 vma->vm_flags |= VM_IO; 238 vma->vm_private_data = info; 239 return 0; 240} 241EXPORT_SYMBOL_GPL(fb_deferred_io_mmap); 242 243/* workqueue callback */ 244static void fb_deferred_io_work(struct work_struct *work) 245{ 246 struct fb_info *info = container_of(work, struct fb_info, deferred_work.work); 247 struct fb_deferred_io_pageref *pageref, *next; 248 struct fb_deferred_io *fbdefio = info->fbdefio; 249 250 /* here we mkclean the pages, then do all deferred IO */ 251 mutex_lock(&fbdefio->lock); 252 list_for_each_entry(pageref, &fbdefio->pagereflist, list) { 253 struct page *cur = pageref->page; 254 lock_page(cur); 255 page_mkclean(cur); 256 unlock_page(cur); 257 } 258 259 /* driver's callback with pagereflist */ 260 fbdefio->deferred_io(info, &fbdefio->pagereflist); 261 262 /* clear the list */ 263 list_for_each_entry_safe(pageref, next, &fbdefio->pagereflist, list) 264 fb_deferred_io_pageref_put(pageref, info); 265 266 mutex_unlock(&fbdefio->lock); 267} 268 269int fb_deferred_io_init(struct fb_info *info) 270{ 271 struct fb_deferred_io *fbdefio = info->fbdefio; 272 struct fb_deferred_io_pageref *pagerefs; 273 unsigned long npagerefs, i; 274 int ret; 275 276 BUG_ON(!fbdefio); 277 278 if (WARN_ON(!info->fix.smem_len)) 279 return -EINVAL; 280 281 mutex_init(&fbdefio->lock); 282 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work); 283 INIT_LIST_HEAD(&fbdefio->pagereflist); 284 if (fbdefio->delay == 0) /* set a default of 1 s */ 285 fbdefio->delay = HZ; 286 287 npagerefs = DIV_ROUND_UP(info->fix.smem_len, PAGE_SIZE); 288 289 /* alloc a page ref for each page of the display memory */ 290 pagerefs = kvcalloc(npagerefs, sizeof(*pagerefs), GFP_KERNEL); 291 if (!pagerefs) { 292 ret = -ENOMEM; 293 goto err; 294 } 295 for (i = 0; i < npagerefs; ++i) 296 INIT_LIST_HEAD(&pagerefs[i].list); 297 info->npagerefs = npagerefs; 298 info->pagerefs = pagerefs; 299 300 return 0; 301 302err: 303 mutex_destroy(&fbdefio->lock); 304 return ret; 305} 306EXPORT_SYMBOL_GPL(fb_deferred_io_init); 307 308void fb_deferred_io_open(struct fb_info *info, 309 struct inode *inode, 310 struct file *file) 311{ 312 file->f_mapping->a_ops = &fb_deferred_io_aops; 313} 314EXPORT_SYMBOL_GPL(fb_deferred_io_open); 315 316void fb_deferred_io_cleanup(struct fb_info *info) 317{ 318 struct fb_deferred_io *fbdefio = info->fbdefio; 319 struct page *page; 320 int i; 321 322 BUG_ON(!fbdefio); 323 cancel_delayed_work_sync(&info->deferred_work); 324 325 /* clear out the mapping that we setup */ 326 for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) { 327 page = fb_deferred_io_page(info, i); 328 page->mapping = NULL; 329 } 330 331 kvfree(info->pagerefs); 332 mutex_destroy(&fbdefio->lock); 333} 334EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);