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 page->index = vmf->pgoff; 56 57 vmf->page = page; 58 return 0; 59 } 60 61 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync) 62 { 63 struct fb_info *info = file->private_data; 64 struct inode *inode = file_inode(file); 65 int err = file_write_and_wait_range(file, start, end); 66 if (err) 67 return err; 68 69 /* Skip if deferred io is compiled-in but disabled on this fbdev */ 70 if (!info->fbdefio) 71 return 0; 72 73 inode_lock(inode); 74 /* Kill off the delayed work */ 75 cancel_delayed_work_sync(&info->deferred_work); 76 77 /* Run it immediately */ 78 schedule_delayed_work(&info->deferred_work, 0); 79 inode_unlock(inode); 80 81 return 0; 82 } 83 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); 84 85 /* vm_ops->page_mkwrite handler */ 86 static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) 87 { 88 struct page *page = vmf->page; 89 struct fb_info *info = vmf->vma->vm_private_data; 90 struct fb_deferred_io *fbdefio = info->fbdefio; 91 struct page *cur; 92 93 /* this is a callback we get when userspace first tries to 94 write to the page. we schedule a workqueue. that workqueue 95 will eventually mkclean the touched pages and execute the 96 deferred framebuffer IO. then if userspace touches a page 97 again, we repeat the same scheme */ 98 99 file_update_time(vmf->vma->vm_file); 100 101 /* protect against the workqueue changing the page list */ 102 mutex_lock(&fbdefio->lock); 103 104 /* first write in this cycle, notify the driver */ 105 if (fbdefio->first_io && list_empty(&fbdefio->pagelist)) 106 fbdefio->first_io(info); 107 108 /* 109 * We want the page to remain locked from ->page_mkwrite until 110 * the PTE is marked dirty to avoid page_mkclean() being called 111 * before the PTE is updated, which would leave the page ignored 112 * by defio. 113 * Do this by locking the page here and informing the caller 114 * about it with VM_FAULT_LOCKED. 115 */ 116 lock_page(page); 117 118 /* we loop through the pagelist before adding in order 119 to keep the pagelist sorted */ 120 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 121 /* this check is to catch the case where a new 122 process could start writing to the same page 123 through a new pte. this new access can cause the 124 mkwrite even when the original ps's pte is marked 125 writable */ 126 if (unlikely(cur == page)) 127 goto page_already_added; 128 else if (cur->index > page->index) 129 break; 130 } 131 132 list_add_tail(&page->lru, &cur->lru); 133 134 page_already_added: 135 mutex_unlock(&fbdefio->lock); 136 137 /* come back after delay to process the deferred IO */ 138 schedule_delayed_work(&info->deferred_work, fbdefio->delay); 139 return VM_FAULT_LOCKED; 140 } 141 142 static const struct vm_operations_struct fb_deferred_io_vm_ops = { 143 .fault = fb_deferred_io_fault, 144 .page_mkwrite = fb_deferred_io_mkwrite, 145 }; 146 147 int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) 148 { 149 vma->vm_ops = &fb_deferred_io_vm_ops; 150 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; 151 if (!(info->flags & FBINFO_VIRTFB)) 152 vma->vm_flags |= VM_IO; 153 vma->vm_private_data = info; 154 return 0; 155 } 156 157 /* workqueue callback */ 158 static void fb_deferred_io_work(struct work_struct *work) 159 { 160 struct fb_info *info = container_of(work, struct fb_info, 161 deferred_work.work); 162 struct list_head *node, *next; 163 struct page *cur; 164 struct fb_deferred_io *fbdefio = info->fbdefio; 165 166 /* here we mkclean the pages, then do all deferred IO */ 167 mutex_lock(&fbdefio->lock); 168 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 169 lock_page(cur); 170 page_mkclean(cur); 171 unlock_page(cur); 172 } 173 174 /* driver's callback with pagelist */ 175 fbdefio->deferred_io(info, &fbdefio->pagelist); 176 177 /* clear the list */ 178 list_for_each_safe(node, next, &fbdefio->pagelist) { 179 list_del(node); 180 } 181 mutex_unlock(&fbdefio->lock); 182 } 183 184 void fb_deferred_io_init(struct fb_info *info) 185 { 186 struct fb_deferred_io *fbdefio = info->fbdefio; 187 188 BUG_ON(!fbdefio); 189 mutex_init(&fbdefio->lock); 190 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work); 191 INIT_LIST_HEAD(&fbdefio->pagelist); 192 if (fbdefio->delay == 0) /* set a default of 1 s */ 193 fbdefio->delay = HZ; 194 } 195 EXPORT_SYMBOL_GPL(fb_deferred_io_init); 196 197 void fb_deferred_io_cleanup(struct fb_info *info) 198 { 199 struct fb_deferred_io *fbdefio = info->fbdefio; 200 201 BUG_ON(!fbdefio); 202 cancel_delayed_work_sync(&info->deferred_work); 203 mutex_destroy(&fbdefio->lock); 204 } 205 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup); 206