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fb: defio nopage

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Convert fb defio from nopage to fault.
Switch from OOM to SIGBUS if the resource is not available.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jaya Kumar <jayakumar.lkml@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Piggin 2008-02-06 01:39:10 -08:00 committed by Linus Torvalds
parent 8c85fd89be
commit 529e55b6a5
2 changed files with 11 additions and 12 deletions
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6
Documentation/fb/deferred_io.txt
View file

@ -7,10 +7,10 @@ IO. The following example may be a useful explanation of how one such setup
works:
- userspace app like Xfbdev mmaps framebuffer
- deferred IO and driver sets up nopage and page_mkwrite handlers
- deferred IO and driver sets up fault and page_mkwrite handlers
- userspace app tries to write to mmaped vaddress
- we get pagefault and reach nopage handler
- nopage handler finds and returns physical page
- we get pagefault and reach fault handler
- fault handler finds and returns physical page
- we get page_mkwrite where we add this page to a list
- schedule a workqueue task to be run after a delay
- app continues writing to that page with no additional cost. this is

17
drivers/video/fb_defio.c
View file

@ -25,8 +25,8 @@
#include <linux/pagemap.h>
/* this is to find and return the vmalloc-ed fb pages */
static struct page* fb_deferred_io_nopage(struct vm_area_struct *vma,
unsigned long vaddr, int *type)
static int fb_deferred_io_fault(struct vm_area_struct *vma,
struct vm_fault *vmf)
{
unsigned long offset;
struct page *page;
@ -34,18 +34,17 @@ static struct page* fb_deferred_io_nopage(struct vm_area_struct *vma,
/* info->screen_base is in System RAM */
void *screen_base = (void __force *) info->screen_base;
offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
offset = vmf->pgoff << PAGE_SHIFT;
if (offset >= info->fix.smem_len)
return NOPAGE_SIGBUS;
return VM_FAULT_SIGBUS;
page = vmalloc_to_page(screen_base + offset);
if (!page)
return NOPAGE_OOM;
return VM_FAULT_SIGBUS;
get_page(page);
if (type)
*type = VM_FAULT_MINOR;
return page;
vmf->page = page;
return 0;
}
int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
@ -84,7 +83,7 @@ static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
}
static struct vm_operations_struct fb_deferred_io_vm_ops = {
.nopage = fb_deferred_io_nopage,
.fault = fb_deferred_io_fault,
.page_mkwrite = fb_deferred_io_mkwrite,
};