drivers/video/fbdev/core/fb_defio.c - linux - Git at Google

 /*
  *  linux/drivers/video/fb_defio.c
  *
  *  Copyright (C) 2006 Jaya Kumar
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License. See the file COPYING in the main directory of this archive
  * for more details.
  */

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/fb.h>
 #include <linux/list.h>

 /* to support deferred IO */
 #include <linux/rmap.h>
 #include <linux/pagemap.h>

 static struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs)
 {
 	void *screen_base = (void __force *) info->screen_base;
 	struct page *page;

 	if (is_vmalloc_addr(screen_base + offs))
 		page = vmalloc_to_page(screen_base + offs);
 	else
 		page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT);

 	return page;
 }

 static struct fb_deferred_io_pageref *fb_deferred_io_pageref_get(struct fb_info *info,
 								 unsigned long offset,
 								 struct page *page)
 {
 	struct fb_deferred_io *fbdefio = info->fbdefio;
 	struct list_head *pos = &fbdefio->pagereflist;
 	unsigned long pgoff = offset >> PAGE_SHIFT;
 	struct fb_deferred_io_pageref *pageref, *cur;

 	if (WARN_ON_ONCE(pgoff >= info->npagerefs))
 		return NULL; /* incorrect allocation size */

 	/* 1:1 mapping between pageref and page offset */
 	pageref = &info->pagerefs[pgoff];

 	/*
 	 * This check is to catch the case where a new process could start
 	 * writing to the same page through a new PTE. This new access
 	 * can cause a call to .page_mkwrite even if the original process'
 	 * PTE is marked writable.
 	 */
 	if (!list_empty(&pageref->list))
 		goto pageref_already_added;

 	pageref->page = page;
 	pageref->offset = pgoff << PAGE_SHIFT;

 	if (unlikely(fbdefio->sort_pagereflist)) {
 		/*
 		 * We loop through the list of pagerefs before adding in
 		 * order to keep the pagerefs sorted. This has significant
 		 * overhead of O(n^2) with n being the number of written
 		 * pages. If possible, drivers should try to work with
 		 * unsorted page lists instead.
 		 */
 		list_for_each_entry(cur, &fbdefio->pagereflist, list) {
 			if (cur->offset > pageref->offset)
 				break;
 		}
 		pos = &cur->list;
 	}

 	list_add_tail(&pageref->list, pos);

 pageref_already_added:
 	return pageref;
 }

 static void fb_deferred_io_pageref_put(struct fb_deferred_io_pageref *pageref,
 				       struct fb_info *info)
 {
 	list_del_init(&pageref->list);
 }

 /* this is to find and return the vmalloc-ed fb pages */
 static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf)
 {
 	unsigned long offset;
 	struct page *page;
 	struct fb_info *info = vmf->vma->vm_private_data;

 	offset = vmf->pgoff << PAGE_SHIFT;
 	if (offset >= info->fix.smem_len)
 		return VM_FAULT_SIGBUS;

 	page = fb_deferred_io_page(info, offset);
 	if (!page)
 		return VM_FAULT_SIGBUS;

 	get_page(page);

 	if (vmf->vma->vm_file)
 		page->mapping = vmf->vma->vm_file->f_mapping;
 	else
 		printk(KERN_ERR "no mapping available\n");

 	BUG_ON(!page->mapping);
 	page->index = vmf->pgoff; /* for page_mkclean() */

 	vmf->page = page;
 	return 0;
 }

 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
 	struct fb_info *info = file->private_data;
 	struct inode *inode = file_inode(file);
 	int err = file_write_and_wait_range(file, start, end);
 	if (err)
 		return err;

 	/* Skip if deferred io is compiled-in but disabled on this fbdev */
 	if (!info->fbdefio)
 		return 0;

 	inode_lock(inode);
 	/* Kill off the delayed work */
 	cancel_delayed_work_sync(&info->deferred_work);

 	/* Run it immediately */
 	schedule_delayed_work(&info->deferred_work, 0);
 	inode_unlock(inode);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);

 /*
  * Adds a page to the dirty list. Call this from struct
  * vm_operations_struct.page_mkwrite.
  */
 static vm_fault_t fb_deferred_io_track_page(struct fb_info *info, unsigned long offset,
 					    struct page *page)
 {
 	struct fb_deferred_io *fbdefio = info->fbdefio;
 	struct fb_deferred_io_pageref *pageref;
 	vm_fault_t ret;

 	/* protect against the workqueue changing the page list */
 	mutex_lock(&fbdefio->lock);

 	/* first write in this cycle, notify the driver */
 	if (fbdefio->first_io && list_empty(&fbdefio->pagereflist))
 		fbdefio->first_io(info);

 	pageref = fb_deferred_io_pageref_get(info, offset, page);
 	if (WARN_ON_ONCE(!pageref)) {
 		ret = VM_FAULT_OOM;
 		goto err_mutex_unlock;
 	}

 	/*
 	 * We want the page to remain locked from ->page_mkwrite until
 	 * the PTE is marked dirty to avoid page_mkclean() being called
 	 * before the PTE is updated, which would leave the page ignored
 	 * by defio.
 	 * Do this by locking the page here and informing the caller
 	 * about it with VM_FAULT_LOCKED.
 	 */
 	lock_page(pageref->page);

 	mutex_unlock(&fbdefio->lock);

 	/* come back after delay to process the deferred IO */
 	schedule_delayed_work(&info->deferred_work, fbdefio->delay);
 	return VM_FAULT_LOCKED;

 err_mutex_unlock:
 	mutex_unlock(&fbdefio->lock);
 	return ret;
 }

 /*
  * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O
  * @fb_info: The fbdev info structure
  * @vmf: The VM fault
  *
  * This is a callback we get when userspace first tries to
  * write to the page. We schedule a workqueue. That workqueue
  * will eventually mkclean the touched pages and execute the
  * deferred framebuffer IO. Then if userspace touches a page
  * again, we repeat the same scheme.
  *
  * Returns:
  * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise.
  */
 static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf)
 {
 	unsigned long offset = vmf->address - vmf->vma->vm_start;
 	struct page *page = vmf->page;

 	file_update_time(vmf->vma->vm_file);

 	return fb_deferred_io_track_page(info, offset, page);
 }

 /* vm_ops->page_mkwrite handler */
 static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf)
 {
 	struct fb_info *info = vmf->vma->vm_private_data;

 	return fb_deferred_io_page_mkwrite(info, vmf);
 }

 static const struct vm_operations_struct fb_deferred_io_vm_ops = {
 	.fault		= fb_deferred_io_fault,
 	.page_mkwrite	= fb_deferred_io_mkwrite,
 };

 static const struct address_space_operations fb_deferred_io_aops = {
 	.dirty_folio	= noop_dirty_folio,
 };

 int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
 {
 	vma->vm_ops = &fb_deferred_io_vm_ops;
 	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 	if (!(info->flags & FBINFO_VIRTFB))
 		vma->vm_flags |= VM_IO;
 	vma->vm_private_data = info;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_mmap);

 /* workqueue callback */
 static void fb_deferred_io_work(struct work_struct *work)
 {
 	struct fb_info *info = container_of(work, struct fb_info, deferred_work.work);
 	struct fb_deferred_io_pageref *pageref, *next;
 	struct fb_deferred_io *fbdefio = info->fbdefio;

 	/* here we mkclean the pages, then do all deferred IO */
 	mutex_lock(&fbdefio->lock);
 	list_for_each_entry(pageref, &fbdefio->pagereflist, list) {
 		struct page *cur = pageref->page;
 		lock_page(cur);
 		page_mkclean(cur);
 		unlock_page(cur);
 	}

 	/* driver's callback with pagereflist */
 	fbdefio->deferred_io(info, &fbdefio->pagereflist);

 	/* clear the list */
 	list_for_each_entry_safe(pageref, next, &fbdefio->pagereflist, list)
 		fb_deferred_io_pageref_put(pageref, info);

 	mutex_unlock(&fbdefio->lock);
 }

 int fb_deferred_io_init(struct fb_info *info)
 {
 	struct fb_deferred_io *fbdefio = info->fbdefio;
 	struct fb_deferred_io_pageref *pagerefs;
 	unsigned long npagerefs, i;
 	int ret;

 	BUG_ON(!fbdefio);

 	if (WARN_ON(!info->fix.smem_len))
 		return -EINVAL;

 	mutex_init(&fbdefio->lock);
 	INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
 	INIT_LIST_HEAD(&fbdefio->pagereflist);
 	if (fbdefio->delay == 0) /* set a default of 1 s */
 		fbdefio->delay = HZ;

 	npagerefs = DIV_ROUND_UP(info->fix.smem_len, PAGE_SIZE);

 	/* alloc a page ref for each page of the display memory */
 	pagerefs = kvcalloc(npagerefs, sizeof(*pagerefs), GFP_KERNEL);
 	if (!pagerefs) {
 		ret = -ENOMEM;
 		goto err;
 	}
 	for (i = 0; i < npagerefs; ++i)
 		INIT_LIST_HEAD(&pagerefs[i].list);
 	info->npagerefs = npagerefs;
 	info->pagerefs = pagerefs;

 	return 0;

 err:
 	mutex_destroy(&fbdefio->lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_init);

 void fb_deferred_io_open(struct fb_info *info,
 			 struct inode *inode,
 			 struct file *file)
 {
 	file->f_mapping->a_ops = &fb_deferred_io_aops;
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_open);

 void fb_deferred_io_cleanup(struct fb_info *info)
 {
 	struct fb_deferred_io *fbdefio = info->fbdefio;
 	struct page *page;
 	int i;

 	BUG_ON(!fbdefio);
 	cancel_delayed_work_sync(&info->deferred_work);

 	/* clear out the mapping that we setup */
 	for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
 		page = fb_deferred_io_page(info, i);
 		page->mapping = NULL;
 	}

 	kvfree(info->pagerefs);
 	mutex_destroy(&fbdefio->lock);
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
	/*
	* linux/drivers/video/fb_defio.c
	*
	* Copyright (C) 2006 Jaya Kumar
	*
	* This file is subject to the terms and conditions of the GNU General Public
	* License. See the file COPYING in the main directory of this archive
	* for more details.
	*/

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/string.h>
	#include <linux/mm.h>
	#include <linux/vmalloc.h>
	#include <linux/delay.h>
	#include <linux/interrupt.h>
	#include <linux/fb.h>
	#include <linux/list.h>

	/* to support deferred IO */
	#include <linux/rmap.h>
	#include <linux/pagemap.h>

	static struct page fb_deferred_io_page(struct fb_info info, unsigned long offs)
	{
	void screen_base = (void __force ) info->screen_base;
	struct page *page;

	if (is_vmalloc_addr(screen_base + offs))
	page = vmalloc_to_page(screen_base + offs);
	else
	page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT);

	return page;
	}

	static struct fb_deferred_io_pageref fb_deferred_io_pageref_get(struct fb_info info,
	unsigned long offset,
	struct page *page)
	{
	struct fb_deferred_io *fbdefio = info->fbdefio;
	struct list_head *pos = &fbdefio->pagereflist;
	unsigned long pgoff = offset >> PAGE_SHIFT;
	struct fb_deferred_io_pageref pageref, cur;

	if (WARN_ON_ONCE(pgoff >= info->npagerefs))
	return NULL; /* incorrect allocation size */

	/* 1:1 mapping between pageref and page offset */
	pageref = &info->pagerefs[pgoff];

	/*
	* This check is to catch the case where a new process could start
	* writing to the same page through a new PTE. This new access
	* can cause a call to .page_mkwrite even if the original process'
	* PTE is marked writable.
	*/
	if (!list_empty(&pageref->list))
	goto pageref_already_added;

	pageref->page = page;
	pageref->offset = pgoff << PAGE_SHIFT;

	if (unlikely(fbdefio->sort_pagereflist)) {
	/*
	* We loop through the list of pagerefs before adding in
	* order to keep the pagerefs sorted. This has significant
	* overhead of O(n^2) with n being the number of written
	* pages. If possible, drivers should try to work with
	* unsorted page lists instead.
	*/
	list_for_each_entry(cur, &fbdefio->pagereflist, list) {
	if (cur->offset > pageref->offset)
	break;
	}
	pos = &cur->list;
	}

	list_add_tail(&pageref->list, pos);

	pageref_already_added:
	return pageref;
	}

	static void fb_deferred_io_pageref_put(struct fb_deferred_io_pageref *pageref,
	struct fb_info *info)
	{
	list_del_init(&pageref->list);
	}

	/* this is to find and return the vmalloc-ed fb pages */
	static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf)
	{
	unsigned long offset;
	struct page *page;
	struct fb_info *info = vmf->vma->vm_private_data;

	offset = vmf->pgoff << PAGE_SHIFT;
	if (offset >= info->fix.smem_len)
	return VM_FAULT_SIGBUS;

	page = fb_deferred_io_page(info, offset);
	if (!page)
	return VM_FAULT_SIGBUS;

	get_page(page);

	if (vmf->vma->vm_file)
	page->mapping = vmf->vma->vm_file->f_mapping;
	else
	printk(KERN_ERR "no mapping available\n");

	BUG_ON(!page->mapping);
	page->index = vmf->pgoff; /* for page_mkclean() */

	vmf->page = page;
	return 0;
	}

	int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
	{
	struct fb_info *info = file->private_data;
	struct inode *inode = file_inode(file);
	int err = file_write_and_wait_range(file, start, end);
	if (err)
	return err;

	/* Skip if deferred io is compiled-in but disabled on this fbdev */
	if (!info->fbdefio)
	return 0;

	inode_lock(inode);
	/* Kill off the delayed work */
	cancel_delayed_work_sync(&info->deferred_work);

	/* Run it immediately */
	schedule_delayed_work(&info->deferred_work, 0);
	inode_unlock(inode);

	return 0;
	}
	EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);

	/*
	* Adds a page to the dirty list. Call this from struct
	* vm_operations_struct.page_mkwrite.
	*/
	static vm_fault_t fb_deferred_io_track_page(struct fb_info *info, unsigned long offset,
	struct page *page)
	{
	struct fb_deferred_io *fbdefio = info->fbdefio;
	struct fb_deferred_io_pageref *pageref;
	vm_fault_t ret;

	/* protect against the workqueue changing the page list */
	mutex_lock(&fbdefio->lock);

	/* first write in this cycle, notify the driver */
	if (fbdefio->first_io && list_empty(&fbdefio->pagereflist))
	fbdefio->first_io(info);

	pageref = fb_deferred_io_pageref_get(info, offset, page);
	if (WARN_ON_ONCE(!pageref)) {
	ret = VM_FAULT_OOM;
	goto err_mutex_unlock;
	}

	/*
	* We want the page to remain locked from ->page_mkwrite until
	* the PTE is marked dirty to avoid page_mkclean() being called
	* before the PTE is updated, which would leave the page ignored
	* by defio.
	* Do this by locking the page here and informing the caller
	* about it with VM_FAULT_LOCKED.
	*/
	lock_page(pageref->page);

	mutex_unlock(&fbdefio->lock);

	/* come back after delay to process the deferred IO */
	schedule_delayed_work(&info->deferred_work, fbdefio->delay);
	return VM_FAULT_LOCKED;

	err_mutex_unlock:
	mutex_unlock(&fbdefio->lock);
	return ret;
	}

	/*
	* fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O
	* @fb_info: The fbdev info structure
	* @vmf: The VM fault
	*
	* This is a callback we get when userspace first tries to
	* write to the page. We schedule a workqueue. That workqueue
	* will eventually mkclean the touched pages and execute the
	* deferred framebuffer IO. Then if userspace touches a page
	* again, we repeat the same scheme.
	*
	* Returns:
	* VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise.
	*/
	static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info info, struct vm_fault vmf)
	{
	unsigned long offset = vmf->address - vmf->vma->vm_start;
	struct page *page = vmf->page;

	file_update_time(vmf->vma->vm_file);

	return fb_deferred_io_track_page(info, offset, page);
	}

	/* vm_ops->page_mkwrite handler */
	static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf)
	{
	struct fb_info *info = vmf->vma->vm_private_data;

	return fb_deferred_io_page_mkwrite(info, vmf);
	}

	static const struct vm_operations_struct fb_deferred_io_vm_ops = {
	.fault = fb_deferred_io_fault,
	.page_mkwrite = fb_deferred_io_mkwrite,
	};

	static const struct address_space_operations fb_deferred_io_aops = {
	.dirty_folio = noop_dirty_folio,
	};

	int fb_deferred_io_mmap(struct fb_info info, struct vm_area_struct vma)
	{
	vma->vm_ops = &fb_deferred_io_vm_ops;
	vma->vm_flags \|= VM_DONTEXPAND \| VM_DONTDUMP;
	if (!(info->flags & FBINFO_VIRTFB))
	vma->vm_flags \|= VM_IO;
	vma->vm_private_data = info;
	return 0;
	}
	EXPORT_SYMBOL_GPL(fb_deferred_io_mmap);

	/* workqueue callback */
	static void fb_deferred_io_work(struct work_struct *work)
	{
	struct fb_info *info = container_of(work, struct fb_info, deferred_work.work);
	struct fb_deferred_io_pageref pageref, next;
	struct fb_deferred_io *fbdefio = info->fbdefio;

	/* here we mkclean the pages, then do all deferred IO */
	mutex_lock(&fbdefio->lock);
	list_for_each_entry(pageref, &fbdefio->pagereflist, list) {
	struct page *cur = pageref->page;
	lock_page(cur);
	page_mkclean(cur);
	unlock_page(cur);
	}

	/* driver's callback with pagereflist */
	fbdefio->deferred_io(info, &fbdefio->pagereflist);

	/* clear the list */
	list_for_each_entry_safe(pageref, next, &fbdefio->pagereflist, list)
	fb_deferred_io_pageref_put(pageref, info);

	mutex_unlock(&fbdefio->lock);
	}

	int fb_deferred_io_init(struct fb_info *info)
	{
	struct fb_deferred_io *fbdefio = info->fbdefio;
	struct fb_deferred_io_pageref *pagerefs;
	unsigned long npagerefs, i;
	int ret;

	BUG_ON(!fbdefio);

	if (WARN_ON(!info->fix.smem_len))
	return -EINVAL;

	mutex_init(&fbdefio->lock);
	INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
	INIT_LIST_HEAD(&fbdefio->pagereflist);
	if (fbdefio->delay == 0) /* set a default of 1 s */
	fbdefio->delay = HZ;

	npagerefs = DIV_ROUND_UP(info->fix.smem_len, PAGE_SIZE);

	/* alloc a page ref for each page of the display memory */
	pagerefs = kvcalloc(npagerefs, sizeof(*pagerefs), GFP_KERNEL);
	if (!pagerefs) {
	ret = -ENOMEM;
	goto err;
	}
	for (i = 0; i < npagerefs; ++i)
	INIT_LIST_HEAD(&pagerefs[i].list);
	info->npagerefs = npagerefs;
	info->pagerefs = pagerefs;

	return 0;

	err:
	mutex_destroy(&fbdefio->lock);
	return ret;
	}
	EXPORT_SYMBOL_GPL(fb_deferred_io_init);

	void fb_deferred_io_open(struct fb_info *info,
	struct inode *inode,
	struct file *file)
	{
	file->f_mapping->a_ops = &fb_deferred_io_aops;
	}
	EXPORT_SYMBOL_GPL(fb_deferred_io_open);

	void fb_deferred_io_cleanup(struct fb_info *info)
	{
	struct fb_deferred_io *fbdefio = info->fbdefio;
	struct page *page;
	int i;

	BUG_ON(!fbdefio);
	cancel_delayed_work_sync(&info->deferred_work);

	/* clear out the mapping that we setup */
	for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
	page = fb_deferred_io_page(info, i);
	page->mapping = NULL;
	}

	kvfree(info->pagerefs);
	mutex_destroy(&fbdefio->lock);
	}
	EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);