root/drivers/video/fbdev/core/fb_defio.c

DEFINITIONS

1. fb_deferred_io_page
2. fb_deferred_io_fault
3. fb_deferred_io_fsync
4. fb_deferred_io_mkwrite
5. fb_deferred_io_set_page_dirty
6. fb_deferred_io_mmap
7. fb_deferred_io_work
8. fb_deferred_io_init
9. fb_deferred_io_open
10. fb_deferred_io_cleanup

   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         page->index = vmf->pgoff;
  63 
  64         vmf->page = page;
  65         return 0;
  66 }
  67 
  68 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
  69 {
  70         struct fb_info *info = file->private_data;
  71         struct inode *inode = file_inode(file);
  72         int err = file_write_and_wait_range(file, start, end);
  73         if (err)
  74                 return err;
  75 
  76         /* Skip if deferred io is compiled-in but disabled on this fbdev */
  77         if (!info->fbdefio)
  78                 return 0;
  79 
  80         inode_lock(inode);
  81         /* Kill off the delayed work */
  82         cancel_delayed_work_sync(&info->deferred_work);
  83 
  84         /* Run it immediately */
  85         schedule_delayed_work(&info->deferred_work, 0);
  86         inode_unlock(inode);
  87 
  88         return 0;
  89 }
  90 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
  91 
  92 /* vm_ops->page_mkwrite handler */
  93 static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf)
  94 {
  95         struct page *page = vmf->page;
  96         struct fb_info *info = vmf->vma->vm_private_data;
  97         struct fb_deferred_io *fbdefio = info->fbdefio;
  98         struct page *cur;
  99 
 100         /* this is a callback we get when userspace first tries to
 101         write to the page. we schedule a workqueue. that workqueue
 102         will eventually mkclean the touched pages and execute the
 103         deferred framebuffer IO. then if userspace touches a page
 104         again, we repeat the same scheme */
 105 
 106         file_update_time(vmf->vma->vm_file);
 107 
 108         /* protect against the workqueue changing the page list */
 109         mutex_lock(&fbdefio->lock);
 110 
 111         /* first write in this cycle, notify the driver */
 112         if (fbdefio->first_io && list_empty(&fbdefio->pagelist))
 113                 fbdefio->first_io(info);
 114 
 115         /*
 116          * We want the page to remain locked from ->page_mkwrite until
 117          * the PTE is marked dirty to avoid page_mkclean() being called
 118          * before the PTE is updated, which would leave the page ignored
 119          * by defio.
 120          * Do this by locking the page here and informing the caller
 121          * about it with VM_FAULT_LOCKED.
 122          */
 123         lock_page(page);
 124 
 125         /* we loop through the pagelist before adding in order
 126         to keep the pagelist sorted */
 127         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
 128                 /* this check is to catch the case where a new
 129                 process could start writing to the same page
 130                 through a new pte. this new access can cause the
 131                 mkwrite even when the original ps's pte is marked
 132                 writable */
 133                 if (unlikely(cur == page))
 134                         goto page_already_added;
 135                 else if (cur->index > page->index)
 136                         break;
 137         }
 138 
 139         list_add_tail(&page->lru, &cur->lru);
 140 
 141 page_already_added:
 142         mutex_unlock(&fbdefio->lock);
 143 
 144         /* come back after delay to process the deferred IO */
 145         schedule_delayed_work(&info->deferred_work, fbdefio->delay);
 146         return VM_FAULT_LOCKED;
 147 }
 148 
 149 static const struct vm_operations_struct fb_deferred_io_vm_ops = {
 150         .fault          = fb_deferred_io_fault,
 151         .page_mkwrite   = fb_deferred_io_mkwrite,
 152 };
 153 
 154 static int fb_deferred_io_set_page_dirty(struct page *page)
 155 {
 156         if (!PageDirty(page))
 157                 SetPageDirty(page);
 158         return 0;
 159 }
 160 
 161 static const struct address_space_operations fb_deferred_io_aops = {
 162         .set_page_dirty = fb_deferred_io_set_page_dirty,
 163 };
 164 
 165 int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
 166 {
 167         vma->vm_ops = &fb_deferred_io_vm_ops;
 168         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 169         if (!(info->flags & FBINFO_VIRTFB))
 170                 vma->vm_flags |= VM_IO;
 171         vma->vm_private_data = info;
 172         return 0;
 173 }
 174 EXPORT_SYMBOL(fb_deferred_io_mmap);
 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);