[S390] Rework create_mem_hole() function
This patch makes the create_mem_hole() function more readable and
fixes some minor bugs (e.g. off-by-one problems).
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/mem_detect.c b/arch/s390/kernel/mem_detect.c
index 19b4568..22d502e 100644
--- a/arch/s390/kernel/mem_detect.c
+++ b/arch/s390/kernel/mem_detect.c
@@ -64,70 +64,82 @@
EXPORT_SYMBOL(detect_memory_layout);
/*
+ * Move memory chunks array from index "from" to index "to"
+ */
+static void mem_chunk_move(struct mem_chunk chunk[], int to, int from)
+{
+ int cnt = MEMORY_CHUNKS - to;
+
+ memmove(&chunk[to], &chunk[from], cnt * sizeof(struct mem_chunk));
+}
+
+/*
+ * Initialize memory chunk
+ */
+static void mem_chunk_init(struct mem_chunk *chunk, unsigned long addr,
+ unsigned long size, int type)
+{
+ chunk->type = type;
+ chunk->addr = addr;
+ chunk->size = size;
+}
+
+/*
* Create memory hole with given address, size, and type
*/
-void create_mem_hole(struct mem_chunk chunks[], unsigned long addr,
+void create_mem_hole(struct mem_chunk chunk[], unsigned long addr,
unsigned long size, int type)
{
- unsigned long start, end, new_size;
- int i;
+ unsigned long lh_start, lh_end, lh_size, ch_start, ch_end, ch_size;
+ int i, ch_type;
for (i = 0; i < MEMORY_CHUNKS; i++) {
- if (chunks[i].size == 0)
+ if (chunk[i].size == 0)
continue;
- if (addr + size < chunks[i].addr)
- continue;
- if (addr >= chunks[i].addr + chunks[i].size)
- continue;
- start = max(addr, chunks[i].addr);
- end = min(addr + size, chunks[i].addr + chunks[i].size);
- new_size = end - start;
- if (new_size == 0)
- continue;
- if (start == chunks[i].addr &&
- end == chunks[i].addr + chunks[i].size) {
- /* Remove chunk */
- chunks[i].type = type;
- } else if (start == chunks[i].addr) {
- /* Make chunk smaller at start */
- if (i >= MEMORY_CHUNKS - 1)
- panic("Unable to create memory hole");
- memmove(&chunks[i + 1], &chunks[i],
- sizeof(struct mem_chunk) *
- (MEMORY_CHUNKS - (i + 1)));
- chunks[i + 1].addr = chunks[i].addr + new_size;
- chunks[i + 1].size = chunks[i].size - new_size;
- chunks[i].size = new_size;
- chunks[i].type = type;
+
+ /* Define chunk properties */
+ ch_start = chunk[i].addr;
+ ch_size = chunk[i].size;
+ ch_end = ch_start + ch_size - 1;
+ ch_type = chunk[i].type;
+
+ /* Is memory chunk hit by memory hole? */
+ if (addr + size <= ch_start)
+ continue; /* No: memory hole in front of chunk */
+ if (addr > ch_end)
+ continue; /* No: memory hole after chunk */
+
+ /* Yes: Define local hole properties */
+ lh_start = max(addr, chunk[i].addr);
+ lh_end = min(addr + size - 1, ch_end);
+ lh_size = lh_end - lh_start + 1;
+
+ if (lh_start == ch_start && lh_end == ch_end) {
+ /* Hole covers complete memory chunk */
+ mem_chunk_init(&chunk[i], lh_start, lh_size, type);
+ } else if (lh_end == ch_end) {
+ /* Hole starts in memory chunk and convers chunk end */
+ mem_chunk_move(chunk, i + 1, i);
+ mem_chunk_init(&chunk[i], ch_start, ch_size - lh_size,
+ ch_type);
+ mem_chunk_init(&chunk[i + 1], lh_start, lh_size, type);
i += 1;
- } else if (end == chunks[i].addr + chunks[i].size) {
- /* Make chunk smaller at end */
- if (i >= MEMORY_CHUNKS - 1)
- panic("Unable to create memory hole");
- memmove(&chunks[i + 1], &chunks[i],
- sizeof(struct mem_chunk) *
- (MEMORY_CHUNKS - (i + 1)));
- chunks[i + 1].addr = start;
- chunks[i + 1].size = new_size;
- chunks[i + 1].type = type;
- chunks[i].size -= new_size;
- i += 1;
+ } else if (lh_start == ch_start) {
+ /* Hole ends in memory chunk */
+ mem_chunk_move(chunk, i + 1, i);
+ mem_chunk_init(&chunk[i], lh_start, lh_size, type);
+ mem_chunk_init(&chunk[i + 1], lh_end + 1,
+ ch_size - lh_size, ch_type);
+ break;
} else {
- /* Create memory hole */
- if (i >= MEMORY_CHUNKS - 2)
- panic("Unable to create memory hole");
- memmove(&chunks[i + 2], &chunks[i],
- sizeof(struct mem_chunk) *
- (MEMORY_CHUNKS - (i + 2)));
- chunks[i + 1].addr = addr;
- chunks[i + 1].size = size;
- chunks[i + 1].type = type;
- chunks[i + 2].addr = addr + size;
- chunks[i + 2].size =
- chunks[i].addr + chunks[i].size - (addr + size);
- chunks[i + 2].type = chunks[i].type;
- chunks[i].size = addr - chunks[i].addr;
- i += 2;
+ /* Hole splits memory chunk */
+ mem_chunk_move(chunk, i + 2, i);
+ mem_chunk_init(&chunk[i], ch_start,
+ lh_start - ch_start, ch_type);
+ mem_chunk_init(&chunk[i + 1], lh_start, lh_size, type);
+ mem_chunk_init(&chunk[i + 2], lh_end + 1,
+ ch_end - lh_end, ch_type);
+ break;
}
}
}