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 26struct 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 */ 40static int fb_deferred_io_fault(struct vm_area_struct *vma, 41 struct vm_fault *vmf) 42{ 43 unsigned long offset; 44 struct page *page; 45 struct fb_info *info = vma->vm_private_data; 46 47 offset = vmf->pgoff << PAGE_SHIFT; 48 if (offset >= info->fix.smem_len) 49 return VM_FAULT_SIGBUS; 50 51 page = fb_deferred_io_page(info, offset); 52 if (!page) 53 return VM_FAULT_SIGBUS; 54 55 get_page(page); 56 57 if (vma->vm_file) 58 page->mapping = vma->vm_file->f_mapping; 59 else 60 printk(KERN_ERR "no mapping available\n"); 61 62 BUG_ON(!page->mapping); 63 page->index = vmf->pgoff; 64 65 vmf->page = page; 66 return 0; 67} 68 69int fb_deferred_io_fsync(struct file *file, int datasync) 70{ 71 struct fb_info *info = file->private_data; 72 73 /* Skip if deferred io is compiled-in but disabled on this fbdev */ 74 if (!info->fbdefio) 75 return 0; 76 77 /* Kill off the delayed work */ 78 cancel_rearming_delayed_work(&info->deferred_work); 79 80 /* Run it immediately */ 81 return schedule_delayed_work(&info->deferred_work, 0); 82} 83EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); 84 85/* vm_ops->page_mkwrite handler */ 86static int fb_deferred_io_mkwrite(struct vm_area_struct *vma, 87 struct vm_fault *vmf) 88{ 89 struct page *page = vmf->page; 90 struct fb_info *info = vma->vm_private_data; 91 struct fb_deferred_io *fbdefio = info->fbdefio; 92 struct page *cur; 93 94 /* this is a callback we get when userspace first tries to 95 write to the page. we schedule a workqueue. that workqueue 96 will eventually mkclean the touched pages and execute the 97 deferred framebuffer IO. then if userspace touches a page 98 again, we repeat the same scheme */ 99 100 /* protect against the workqueue changing the page list */ 101 mutex_lock(&fbdefio->lock); 102 103 /* 104 * We want the page to remain locked from ->page_mkwrite until 105 * the PTE is marked dirty to avoid page_mkclean() being called 106 * before the PTE is updated, which would leave the page ignored 107 * by defio. 108 * Do this by locking the page here and informing the caller 109 * about it with VM_FAULT_LOCKED. 110 */ 111 lock_page(page); 112 113 /* we loop through the pagelist before adding in order 114 to keep the pagelist sorted */ 115 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 116 /* this check is to catch the case where a new 117 process could start writing to the same page 118 through a new pte. this new access can cause the 119 mkwrite even when the original ps's pte is marked 120 writable */ 121 if (unlikely(cur == page)) 122 goto page_already_added; 123 else if (cur->index > page->index) 124 break; 125 } 126 127 list_add_tail(&page->lru, &cur->lru); 128 129page_already_added: 130 mutex_unlock(&fbdefio->lock); 131 132 /* come back after delay to process the deferred IO */ 133 schedule_delayed_work(&info->deferred_work, fbdefio->delay); 134 return VM_FAULT_LOCKED; 135} 136 137static const struct vm_operations_struct fb_deferred_io_vm_ops = { 138 .fault = fb_deferred_io_fault, 139 .page_mkwrite = fb_deferred_io_mkwrite, 140}; 141 142static int fb_deferred_io_set_page_dirty(struct page *page) 143{ 144 if (!PageDirty(page)) 145 SetPageDirty(page); 146 return 0; 147} 148 149static const struct address_space_operations fb_deferred_io_aops = { 150 .set_page_dirty = fb_deferred_io_set_page_dirty, 151}; 152 153static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) 154{ 155 vma->vm_ops = &fb_deferred_io_vm_ops; 156 vma->vm_flags |= ( VM_RESERVED | VM_DONTEXPAND ); 157 if (!(info->flags & FBINFO_VIRTFB)) 158 vma->vm_flags |= VM_IO; 159 vma->vm_private_data = info; 160 return 0; 161} 162 163/* workqueue callback */ 164static void fb_deferred_io_work(struct work_struct *work) 165{ 166 struct fb_info *info = container_of(work, struct fb_info, 167 deferred_work.work); 168 struct list_head *node, *next; 169 struct page *cur; 170 struct fb_deferred_io *fbdefio = info->fbdefio; 171 172 /* here we mkclean the pages, then do all deferred IO */ 173 mutex_lock(&fbdefio->lock); 174 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 175 lock_page(cur); 176 page_mkclean(cur); 177 unlock_page(cur); 178 } 179 180 /* driver's callback with pagelist */ 181 fbdefio->deferred_io(info, &fbdefio->pagelist); 182 183 /* clear the list */ 184 list_for_each_safe(node, next, &fbdefio->pagelist) { 185 list_del(node); 186 } 187 mutex_unlock(&fbdefio->lock); 188} 189 190void fb_deferred_io_init(struct fb_info *info) 191{ 192 struct fb_deferred_io *fbdefio = info->fbdefio; 193 194 BUG_ON(!fbdefio); 195 mutex_init(&fbdefio->lock); 196 info->fbops->fb_mmap = fb_deferred_io_mmap; 197 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work); 198 INIT_LIST_HEAD(&fbdefio->pagelist); 199 if (fbdefio->delay == 0) /* set a default of 1 s */ 200 fbdefio->delay = HZ; 201} 202EXPORT_SYMBOL_GPL(fb_deferred_io_init); 203 204void fb_deferred_io_open(struct fb_info *info, 205 struct inode *inode, 206 struct file *file) 207{ 208 file->f_mapping->a_ops = &fb_deferred_io_aops; 209} 210EXPORT_SYMBOL_GPL(fb_deferred_io_open); 211 212void fb_deferred_io_cleanup(struct fb_info *info) 213{ 214 struct fb_deferred_io *fbdefio = info->fbdefio; 215 struct page *page; 216 int i; 217 218 BUG_ON(!fbdefio); 219 cancel_delayed_work(&info->deferred_work); 220 flush_scheduled_work(); 221 222 /* clear out the mapping that we setup */ 223 for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) { 224 page = fb_deferred_io_page(info, i); 225 page->mapping = NULL; 226 } 227 228 info->fbops->fb_mmap = NULL; 229 mutex_destroy(&fbdefio->lock); 230} 231EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup); 232 233MODULE_LICENSE("GPL"); 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