diff options
Diffstat (limited to 'drivers/video')
| -rw-r--r-- | drivers/video/fbdev/broadsheetfb.c | 1 | ||||
| -rw-r--r-- | drivers/video/fbdev/core/fb_defio.c | 48 | ||||
| -rw-r--r-- | drivers/video/fbdev/metronomefb.c | 1 | ||||
| -rw-r--r-- | drivers/video/fbdev/udlfb.c | 1 |
4 files changed, 36 insertions, 15 deletions
diff --git a/drivers/video/fbdev/broadsheetfb.c b/drivers/video/fbdev/broadsheetfb.c index fd66f4d4a621..b9054f658838 100644 --- a/drivers/video/fbdev/broadsheetfb.c +++ b/drivers/video/fbdev/broadsheetfb.c @@ -1059,6 +1059,7 @@ static const struct fb_ops broadsheetfb_ops = { static struct fb_deferred_io broadsheetfb_defio = { .delay = HZ/4, + .sort_pagelist = true, .deferred_io = broadsheetfb_dpy_deferred_io, }; diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c index a591d291b231..98b0f23bf5e2 100644 --- a/drivers/video/fbdev/core/fb_defio.c +++ b/drivers/video/fbdev/core/fb_defio.c @@ -59,6 +59,7 @@ static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf) printk(KERN_ERR "no mapping available\n"); BUG_ON(!page->mapping); + INIT_LIST_HEAD(&page->lru); page->index = vmf->pgoff; vmf->page = page; @@ -95,7 +96,7 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) struct page *page = vmf->page; struct fb_info *info = vmf->vma->vm_private_data; struct fb_deferred_io *fbdefio = info->fbdefio; - struct page *cur; + struct list_head *pos = &fbdefio->pagelist; /* this is a callback we get when userspace first tries to write to the page. we schedule a workqueue. that workqueue @@ -122,21 +123,38 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) */ lock_page(page); - /* we loop through the pagelist before adding in order - to keep the pagelist sorted */ - list_for_each_entry(cur, &fbdefio->pagelist, lru) { - /* 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 the - mkwrite even when the original ps's pte is marked - writable */ - if (unlikely(cur == page)) - goto page_already_added; - else if (cur->index > page->index) - break; + /* + * 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. + * + * TODO: The lru field is owned by the page cache; hence the name. + * We dequeue in fb_deferred_io_work() after flushing the + * page's content into video memory. Instead of lru, fbdefio + * should have it's own field. + */ + if (!list_empty(&page->lru)) + goto page_already_added; + + if (unlikely(fbdefio->sort_pagelist)) { + /* + * We loop through the pagelist before adding in order to + * keep the pagelist 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. + */ + struct page *cur; + + list_for_each_entry(cur, &fbdefio->pagelist, lru) { + if (cur->index > page->index) + break; + } + pos = &cur->lru; } - list_add_tail(&page->lru, &cur->lru); + list_add_tail(&page->lru, pos); page_already_added: mutex_unlock(&fbdefio->lock); @@ -194,7 +212,7 @@ static void fb_deferred_io_work(struct work_struct *work) /* clear the list */ list_for_each_safe(node, next, &fbdefio->pagelist) { - list_del(node); + list_del_init(node); } mutex_unlock(&fbdefio->lock); } diff --git a/drivers/video/fbdev/metronomefb.c b/drivers/video/fbdev/metronomefb.c index 952826557a0c..af858dd23ea6 100644 --- a/drivers/video/fbdev/metronomefb.c +++ b/drivers/video/fbdev/metronomefb.c @@ -568,6 +568,7 @@ static const struct fb_ops metronomefb_ops = { static struct fb_deferred_io metronomefb_defio = { .delay = HZ, + .sort_pagelist = true, .deferred_io = metronomefb_dpy_deferred_io, }; diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c index b9cdd02c1000..184bb8433b78 100644 --- a/drivers/video/fbdev/udlfb.c +++ b/drivers/video/fbdev/udlfb.c @@ -980,6 +980,7 @@ static int dlfb_ops_open(struct fb_info *info, int user) if (fbdefio) { fbdefio->delay = DL_DEFIO_WRITE_DELAY; + fbdefio->sort_pagelist = true; fbdefio->deferred_io = dlfb_dpy_deferred_io; } |