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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                 :          0 : static struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs)
      27                 :            : {
      28                 :          0 :         void *screen_base = (void __force *) info->screen_base;
      29                 :            :         struct page *page;
      30                 :            : 
      31         [ #  # ]:          0 :         if (is_vmalloc_addr(screen_base + offs))
      32                 :          0 :                 page = vmalloc_to_page(screen_base + offs);
      33                 :            :         else
      34                 :          0 :                 page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT);
      35                 :            : 
      36                 :          0 :         return page;
      37                 :            : }
      38                 :            : 
      39                 :            : /* this is to find and return the vmalloc-ed fb pages */
      40                 :          0 : static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf)
      41                 :            : {
      42                 :            :         unsigned long offset;
      43                 :            :         struct page *page;
      44                 :          0 :         struct fb_info *info = vmf->vma->vm_private_data;
      45                 :            : 
      46                 :          0 :         offset = vmf->pgoff << PAGE_SHIFT;
      47         [ #  # ]:          0 :         if (offset >= info->fix.smem_len)
      48                 :            :                 return VM_FAULT_SIGBUS;
      49                 :            : 
      50                 :          0 :         page = fb_deferred_io_page(info, offset);
      51         [ #  # ]:          0 :         if (!page)
      52                 :            :                 return VM_FAULT_SIGBUS;
      53                 :            : 
      54                 :          0 :         get_page(page);
      55                 :            : 
      56         [ #  # ]:          0 :         if (vmf->vma->vm_file)
      57                 :          0 :                 page->mapping = vmf->vma->vm_file->f_mapping;
      58                 :            :         else
      59                 :          0 :                 printk(KERN_ERR "no mapping available\n");
      60                 :            : 
      61         [ #  # ]:          0 :         BUG_ON(!page->mapping);
      62                 :          0 :         page->index = vmf->pgoff;
      63                 :            : 
      64                 :          0 :         vmf->page = page;
      65                 :          0 :         return 0;
      66                 :            : }
      67                 :            : 
      68                 :          0 : int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
      69                 :            : {
      70                 :          0 :         struct fb_info *info = file->private_data;
      71                 :            :         struct inode *inode = file_inode(file);
      72                 :          0 :         int err = file_write_and_wait_range(file, start, end);
      73         [ #  # ]:          0 :         if (err)
      74                 :            :                 return err;
      75                 :            : 
      76                 :            :         /* Skip if deferred io is compiled-in but disabled on this fbdev */
      77         [ #  # ]:          0 :         if (!info->fbdefio)
      78                 :            :                 return 0;
      79                 :            : 
      80                 :            :         inode_lock(inode);
      81                 :            :         /* Kill off the delayed work */
      82                 :          0 :         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                 :          0 :         return 0;
      89                 :            : }
      90                 :            : EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
      91                 :            : 
      92                 :            : /* vm_ops->page_mkwrite handler */
      93                 :          0 : static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf)
      94                 :            : {
      95                 :          0 :         struct page *page = vmf->page;
      96                 :          0 :         struct fb_info *info = vmf->vma->vm_private_data;
      97                 :          0 :         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                 :          0 :         file_update_time(vmf->vma->vm_file);
     107                 :            : 
     108                 :            :         /* protect against the workqueue changing the page list */
     109                 :          0 :         mutex_lock(&fbdefio->lock);
     110                 :            : 
     111                 :            :         /* first write in this cycle, notify the driver */
     112   [ #  #  #  # ]:          0 :         if (fbdefio->first_io && list_empty(&fbdefio->pagelist))
     113                 :          0 :                 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                 :          0 :         lock_page(page);
     124                 :            : 
     125                 :            :         /* we loop through the pagelist before adding in order
     126                 :            :         to keep the pagelist sorted */
     127         [ #  # ]:          0 :         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         [ #  # ]:          0 :                 if (unlikely(cur == page))
     134                 :            :                         goto page_already_added;
     135         [ #  # ]:          0 :                 else if (cur->index > page->index)
     136                 :            :                         break;
     137                 :            :         }
     138                 :            : 
     139                 :          0 :         list_add_tail(&page->lru, &cur->lru);
     140                 :            : 
     141                 :            : page_already_added:
     142                 :          0 :         mutex_unlock(&fbdefio->lock);
     143                 :            : 
     144                 :            :         /* come back after delay to process the deferred IO */
     145                 :          0 :         schedule_delayed_work(&info->deferred_work, fbdefio->delay);
     146                 :          0 :         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                 :          0 : static int fb_deferred_io_set_page_dirty(struct page *page)
     155                 :            : {
     156         [ #  # ]:          0 :         if (!PageDirty(page))
     157                 :            :                 SetPageDirty(page);
     158                 :          0 :         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                 :          0 : int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
     166                 :            : {
     167                 :          0 :         vma->vm_ops = &fb_deferred_io_vm_ops;
     168                 :          0 :         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
     169         [ #  # ]:          0 :         if (!(info->flags & FBINFO_VIRTFB))
     170                 :          0 :                 vma->vm_flags |= VM_IO;
     171                 :          0 :         vma->vm_private_data = info;
     172                 :          0 :         return 0;
     173                 :            : }
     174                 :            : EXPORT_SYMBOL(fb_deferred_io_mmap);
     175                 :            : 
     176                 :            : /* workqueue callback */
     177                 :          0 : static void fb_deferred_io_work(struct work_struct *work)
     178                 :            : {
     179                 :          0 :         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                 :          0 :         struct fb_deferred_io *fbdefio = info->fbdefio;
     184                 :            : 
     185                 :            :         /* here we mkclean the pages, then do all deferred IO */
     186                 :          0 :         mutex_lock(&fbdefio->lock);
     187         [ #  # ]:          0 :         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
     188                 :          0 :                 lock_page(cur);
     189                 :          0 :                 page_mkclean(cur);
     190                 :          0 :                 unlock_page(cur);
     191                 :            :         }
     192                 :            : 
     193                 :            :         /* driver's callback with pagelist */
     194                 :          0 :         fbdefio->deferred_io(info, &fbdefio->pagelist);
     195                 :            : 
     196                 :            :         /* clear the list */
     197         [ #  # ]:          0 :         list_for_each_safe(node, next, &fbdefio->pagelist) {
     198                 :            :                 list_del(node);
     199                 :            :         }
     200                 :          0 :         mutex_unlock(&fbdefio->lock);
     201                 :          0 : }
     202                 :            : 
     203                 :          0 : void fb_deferred_io_init(struct fb_info *info)
     204                 :            : {
     205                 :          0 :         struct fb_deferred_io *fbdefio = info->fbdefio;
     206                 :            : 
     207         [ #  # ]:          0 :         BUG_ON(!fbdefio);
     208                 :          0 :         mutex_init(&fbdefio->lock);
     209                 :          0 :         info->fbops->fb_mmap = fb_deferred_io_mmap;
     210                 :          0 :         INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
     211                 :          0 :         INIT_LIST_HEAD(&fbdefio->pagelist);
     212         [ #  # ]:          0 :         if (fbdefio->delay == 0) /* set a default of 1 s */
     213                 :          0 :                 fbdefio->delay = HZ;
     214                 :          0 : }
     215                 :            : EXPORT_SYMBOL_GPL(fb_deferred_io_init);
     216                 :            : 
     217                 :          0 : void fb_deferred_io_open(struct fb_info *info,
     218                 :            :                          struct inode *inode,
     219                 :            :                          struct file *file)
     220                 :            : {
     221                 :          0 :         file->f_mapping->a_ops = &fb_deferred_io_aops;
     222                 :          0 : }
     223                 :            : EXPORT_SYMBOL_GPL(fb_deferred_io_open);
     224                 :            : 
     225                 :          0 : void fb_deferred_io_cleanup(struct fb_info *info)
     226                 :            : {
     227                 :          0 :         struct fb_deferred_io *fbdefio = info->fbdefio;
     228                 :            :         struct page *page;
     229                 :            :         int i;
     230                 :            : 
     231         [ #  # ]:          0 :         BUG_ON(!fbdefio);
     232                 :          0 :         cancel_delayed_work_sync(&info->deferred_work);
     233                 :            : 
     234                 :            :         /* clear out the mapping that we setup */
     235         [ #  # ]:          0 :         for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
     236                 :          0 :                 page = fb_deferred_io_page(info, i);
     237                 :          0 :                 page->mapping = NULL;
     238                 :            :         }
     239                 :            : 
     240                 :          0 :         info->fbops->fb_mmap = NULL;
     241                 :            :         mutex_destroy(&fbdefio->lock);
     242                 :          0 : }
     243                 :            : EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);