early_res: Add free_early_partial()

To free partial areas in pcpu_setup...

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
LKML-Reference: <4B85E245.5030001@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 55 insertions, 0 deletions

diff --git a/kernel/early_res.c b/kernel/early_res.c
index aa5494ac4462..9ab11cd84853 100644
--- a/kernel/early_res.c
+++ b/kernel/early_res.c
@@ -61,6 +61,40 @@ static void __init drop_range(int i)
         early_res_count--;
 }
 
+static void __init drop_range_partial(int i, u64 start, u64 end)
+{
+        u64 common_start, common_end;
+        u64 old_start, old_end;
+
+        old_start = early_res[i].start;
+        old_end = early_res[i].end;
+        common_start = max(old_start, start);
+        common_end = min(old_end, end);
+
+        /* no overlap ? */
+        if (common_start >= common_end)
+                return;
+
+        if (old_start < common_start) {
+                /* make head segment */
+                early_res[i].end = common_start;
+                if (old_end > common_end) {
+                        /* add another for left over on tail */
+                        reserve_early_without_check(common_end, old_end,
+                                         early_res[i].name);
+                }
+                return;
+        } else {
+                if (old_end > common_end) {
+                        /* reuse the entry for tail left */
+                        early_res[i].start = common_end;
+                        return;
+                }
+                /* all covered */
+                drop_range(i);
+        }
+}
+
 /*
  * Split any existing ranges that:
  *  1) are marked 'overlap_ok', and
@@ -284,6 +318,27 @@ void __init free_early(u64 start, u64 end)
         drop_range(i);
 }
 
+void __init free_early_partial(u64 start, u64 end)
+{
+        struct early_res *r;
+        int i;
+
+try_next:
+        i = find_overlapped_early(start, end);
+        if (i >= max_early_res)
+                return;
+
+        r = &early_res[i];
+        /* hole ? */
+        if (r->end >= end && r->start <= start) {
+                drop_range_partial(i, start, end);
+                return;
+        }
+
+        drop_range_partial(i, start, end);
+        goto try_next;
+}
+
 #ifdef CONFIG_NO_BOOTMEM
 static void __init subtract_early_res(struct range *range, int az)
 {