[PATCH][Lucid SRU] drm: mm: fix range restricted allocations

[Herton Ronaldo Krzesinski]

On Fri, Oct 14, 2011 at 10:05:50AM -0500, Seth Forshee wrote:
> From: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> With the code cleanup in
> 
> 7a6b2896f261894dde287d3faefa4b432cddca53 is the first bad commit
> commit 7a6b2896f261894dde287d3faefa4b432cddca53
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Fri Jul 2 15:02:15 2010 +0100
> 
>     drm_mm: extract check_free_mm_node
> 
> I've botched up the range-restriction checks. The result is usually
> an X server dying with SIGBUS in libpixman (software fallback rendering).
> Change the code to adjust the start and end for range restricted
> allocations. IMHO this even makes the code a bit clearer.
> 
> Fixes regression bug: https://bugs.freedesktop.org/show_bug.cgi?id=29738
> 
> Reported-by-Tested-by: Till MAtthiesen <entropy at everymail.net>
> Acked-by: Alex Deucher <alexdeucher at gmail.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> (backported from commit 7521473305f1379403b893a30ac09a2132dc1e25 upstream)
> 
> BugLink: http://bugs.launchpad.net/bugs/873130
> Signed-off-by: Seth Forshee <seth.forshee at canonical.com>

Fixes the regression in the backport, as tested by the reporter:

Acked-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>


> ---
>  drivers/gpu/drm/drm_mm.c |   29 +++++++++++++++--------------
>  1 files changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> index f1d3314..5a23a9b 100644
> --- a/drivers/gpu/drm/drm_mm.c
> +++ b/drivers/gpu/drm/drm_mm.c
> @@ -330,21 +330,21 @@ void drm_mm_put_block(struct drm_mm_node *cur)
>  
>  EXPORT_SYMBOL(drm_mm_put_block);
>  
> -static int check_free_mm_node(struct drm_mm_node *entry, unsigned long size,
> -			      unsigned alignment)
> +static int check_free_hole(unsigned long start, unsigned long end,
> +			   unsigned long size, unsigned alignment)
>  {
>  	unsigned wasted = 0;
>  
> -	if (entry->size < size)
> +	if (end - start < size)
>  		return 0;
>  
>  	if (alignment) {
> -		register unsigned tmp = entry->start % alignment;
> +		unsigned tmp = start % alignment;
>  		if (tmp)
>  			wasted = alignment - tmp;
>  	}
>  
> -	if (entry->size >= size + wasted) {
> +	if (end >= start + size + wasted) {
>  		return 1;
>  	}
>  
> @@ -369,7 +369,8 @@ struct drm_mm_node *drm_mm_search_free(const struct drm_mm *mm,
>  	list_for_each(list, free_stack) {
>  		entry = list_entry(list, struct drm_mm_node, fl_entry);
>  
> -		if (!check_free_mm_node(entry, size, alignment))
> +		if (!check_free_hole(entry->start, entry->start + entry->size,
> +				     size, alignment))
>  			continue;
>  
>  		if (!best_match)
> @@ -392,7 +393,6 @@ struct drm_mm_node *drm_mm_search_free_in_range(const struct drm_mm *mm,
>  						unsigned long end,
>  						int best_match)
>  {
> -	struct list_head *list;
>  	const struct list_head *free_stack = &mm->fl_entry;
>  	struct drm_mm_node *entry;
>  	struct drm_mm_node *best;
> @@ -403,13 +403,13 @@ struct drm_mm_node *drm_mm_search_free_in_range(const struct drm_mm *mm,
>  	best = NULL;
>  	best_size = ~0UL;
>  
> -	list_for_each(list, free_stack) {
> -		entry = list_entry(list, struct drm_mm_node, fl_entry);
> -
> -		if (entry->start > end || (entry->start+entry->size) < start)
> -			continue;
> +	list_for_each_entry(entry, free_stack, fl_entry) {
> +		unsigned long adj_start = entry->start < start ?
> +			start : entry->start;
> +		unsigned long adj_end = entry->start + entry->size > end ?
> +			end : entry->start + entry->size;
>  
> -		if (!check_free_mm_node(entry, size, alignment))
> +		if (!check_free_hole(adj_start, adj_end, size, alignment))
>  			continue;
>  
>  		if (!best_match)
> @@ -502,7 +502,8 @@ int drm_mm_scan_add_block(struct drm_mm_node *node)
>  	node->fl_entry.prev = prev_free;
>  	node->fl_entry.next = next_free;
>  
> -	if (check_free_mm_node(node, mm->scan_size, mm->scan_alignment)) {
> +	if (check_free_hole(node->start, node->start + node->size,
> +			    mm->scan_size, mm->scan_alignment)) {
>  		mm->scan_hit_start = node->start;
>  		mm->scan_hit_size = node->size;
>  
> -- 
> 1.7.5.4
> 
> 
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team
> 

-- 
[]'s
Herton