[PATCH v2 2/6] lmb: handle scenario of encompassing overlap

[Heinrich Schuchardt]

On 20.02.25 10:56, Sughosh Ganu wrote:
> The lmb_fix_over_lap_regions() function is called if the added region
> overlaps with an existing region. The function then fixes the overlap
> and removes the redundant region. However, it makes certain
> assumptions. One assumption is that the overlap would not encompass
> the existing region. Another assumption is that the overlap only
> occurs between two regions -- the scenario of the added region
> overlapping multiple existing regions is not being handled. Handle
> these cases by instead calling lmb_resize_regions(). Also remove the
> now superfluous lmb_fix_over_lap_regions().
> 
> Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> ---
> Changes since V1:
> * Use lmb_resize_regions() to fix the overlap instead of
>    lmb_fix_over_lap_regions().
> * Remove the now superfluous lmb_fix_over_lap_regions().
> 
> 
> Note: To be applied after an A-b/R-b/T-b from the original author of
>        lmb_fix_over_lap_regions().
> 
> 
>   lib/lmb.c | 30 +++++++++---------------------
>   1 file changed, 9 insertions(+), 21 deletions(-)
> 
> diff --git a/lib/lmb.c b/lib/lmb.c
> index d7d2c8c6dfd..207f059ceb9 100644
> --- a/lib/lmb.c
> +++ b/lib/lmb.c
> @@ -100,25 +100,6 @@ static void lmb_coalesce_regions(struct alist *lmb_rgn_lst, unsigned long r1,
>   	lmb_remove_region(lmb_rgn_lst, r2);
>   }
>   
> -/*Assumption : base addr of region 1 < base addr of region 2*/
> -static void lmb_fix_over_lap_regions(struct alist *lmb_rgn_lst,
> -				     unsigned long r1, unsigned long r2)
> -{
> -	struct lmb_region *rgn = lmb_rgn_lst->data;
> -
> -	phys_addr_t base1 = rgn[r1].base;
> -	phys_size_t size1 = rgn[r1].size;
> -	phys_addr_t base2 = rgn[r2].base;
> -	phys_size_t size2 = rgn[r2].size;
> -
> -	if (base1 + size1 > base2 + size2) {
> -		printf("This will not be a case any time\n");
> -		return;
> -	}
> -	rgn[r1].size = base2 + size2 - base1;
> -	lmb_remove_region(lmb_rgn_lst, r2);
> -}
> -
>   static long lmb_resize_regions(struct alist *lmb_rgn_lst,
>   			       unsigned long idx_start,
>   			       phys_addr_t base, phys_size_t size)
> @@ -239,8 +220,15 @@ static long lmb_add_region_flags(struct alist *lmb_rgn_lst, phys_addr_t base,
>   				lmb_coalesce_regions(lmb_rgn_lst, i, i + 1);
>   				coalesced++;
>   			} else if (lmb_regions_overlap(lmb_rgn_lst, i, i + 1)) {
> -				/* fix overlapping area */
> -				lmb_fix_over_lap_regions(lmb_rgn_lst, i, i + 1);
> +				/* fix overlapping areas */
> +				phys_addr_t rgnbase = rgn[i].base;
> +				phys_size_t rgnsize = rgn[i].size;
> +
> +				ret = lmb_resize_regions(lmb_rgn_lst, i,
> +							 rgnbase, rgnsize);
> +				if (ret < 0)
> +					return -1;
> +
>   				coalesced++;
>   			}
>   		}

It would be great if in a future patch you could document all LMB 
functions like lmb_resize_regions() which lack a function description.

Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>