[PATCH v2 01/11] dump: Cleanup memblock usage

[Janosch Frank]

The iteration over the memblocks is hard to understand so it's about
time to clean it up.

struct DumpState's next_block and start members can and should be
local variables within the iterator.

Instead of manually grabbing the next memblock we can use
QTAILQ_FOREACH to iterate over all memblocks.

The begin and length fields in the DumpState have been left untouched
since the qmp arguments share their names.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 dump/dump.c           | 91 +++++++++++--------------------------------
 include/sysemu/dump.h | 47 +++++++++++++++++++---
 2 files changed, 65 insertions(+), 73 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index 4d9658ffa2..6feba3cbfa 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -591,56 +591,27 @@ static void dump_begin(DumpState *s, Error **errp)
     write_elf_notes(s, errp);
 }
 
-static int get_next_block(DumpState *s, GuestPhysBlock *block)
-{
-    while (1) {
-        block = QTAILQ_NEXT(block, next);
-        if (!block) {
-            /* no more block */
-            return 1;
-        }
-
-        s->start = 0;
-        s->next_block = block;
-        if (s->has_filter) {
-            if (block->target_start >= s->begin + s->length ||
-                block->target_end <= s->begin) {
-                /* This block is out of the range */
-                continue;
-            }
-
-            if (s->begin > block->target_start) {
-                s->start = s->begin - block->target_start;
-            }
-        }
-
-        return 0;
-    }
-}
-
 /* write all memory to vmcore */
 static void dump_iterate(DumpState *s, Error **errp)
 {
     ERRP_GUARD();
     GuestPhysBlock *block;
-    int64_t size;
+    int64_t memblock_size, memblock_start;
 
-    do {
-        block = s->next_block;
-
-        size = block->target_end - block->target_start;
-        if (s->has_filter) {
-            size -= s->start;
-            if (s->begin + s->length < block->target_end) {
-                size -= block->target_end - (s->begin + s->length);
-            }
+    QTAILQ_FOREACH(block, &s->guest_phys_blocks.head, next) {
+        memblock_start = dump_get_memblock_start(block, s->begin, s->length);
+        if (memblock_start == -1) {
+            continue;
         }
-        write_memory(s, block, s->start, size, errp);
+
+        memblock_size = dump_get_memblock_size(block, s->begin, s->length);
+
+        /* Write the memory to file */
+        write_memory(s, block, memblock_start, memblock_size, errp);
         if (*errp) {
             return;
         }
-
-    } while (!get_next_block(s, block));
+    }
 }
 
 static void create_vmcore(DumpState *s, Error **errp)
@@ -1490,30 +1461,22 @@ static void create_kdump_vmcore(DumpState *s, Error 
**errp)
     }
 }
 
-static ram_addr_t get_start_block(DumpState *s)
+static int validate_start_block(DumpState *s)
 {
     GuestPhysBlock *block;
 
     if (!s->has_filter) {
-        s->next_block = QTAILQ_FIRST(&s->guest_phys_blocks.head);
         return 0;
     }
 
     QTAILQ_FOREACH(block, &s->guest_phys_blocks.head, next) {
+        /* This block is out of the range */
         if (block->target_start >= s->begin + s->length ||
             block->target_end <= s->begin) {
-            /* This block is out of the range */
             continue;
         }
-
-        s->next_block = block;
-        if (s->begin > block->target_start) {
-            s->start = s->begin - block->target_start;
-        } else {
-            s->start = 0;
-        }
-        return s->start;
-    }
+        return 0;
+   }
 
     return -1;
 }
@@ -1540,25 +1503,17 @@ bool qemu_system_dump_in_progress(void)
     return (qatomic_read(&state->status) == DUMP_STATUS_ACTIVE);
 }
 
-/* calculate total size of memory to be dumped (taking filter into
- * acoount.) */
+/*
+ * calculate total size of memory to be dumped (taking filter into
+ * account.)
+ */
 static int64_t dump_calculate_size(DumpState *s)
 {
     GuestPhysBlock *block;
-    int64_t size = 0, total = 0, left = 0, right = 0;
+    int64_t total = 0;
 
     QTAILQ_FOREACH(block, &s->guest_phys_blocks.head, next) {
-        if (s->has_filter) {
-            /* calculate the overlapped region. */
-            left = MAX(s->begin, block->target_start);
-            right = MIN(s->begin + s->length, block->target_end);
-            size = right - left;
-            size = size > 0 ? size : 0;
-        } else {
-            /* count the whole region in */
-            size = (block->target_end - block->target_start);
-        }
-        total += size;
+        total += dump_get_memblock_size(block, s->begin, s->length);
     }
 
     return total;
@@ -1660,8 +1615,8 @@ static void dump_init(DumpState *s, int fd, bool 
has_format,
         goto cleanup;
     }
 
-    s->start = get_start_block(s);
-    if (s->start == -1) {
+    /* Is the filter filtering everything? */
+    if (validate_start_block(s) == -1) {
         error_setg(errp, QERR_INVALID_PARAMETER, "begin");
         goto cleanup;
     }
diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
index ffc2ea1072..f3bf98c220 100644
--- a/include/sysemu/dump.h
+++ b/include/sysemu/dump.h
@@ -166,11 +166,10 @@ typedef struct DumpState {
     hwaddr memory_offset;
     int fd;
 
-    GuestPhysBlock *next_block;
-    ram_addr_t start;
-    bool has_filter;
-    int64_t begin;
-    int64_t length;
+    /* Guest memory related data */
+    bool has_filter;           /* Are we dumping parts of the memory? */
+    int64_t begin;             /* Start address of the chunk we want to dump */
+    int64_t length;            /* Length of the dump we want to dump */
 
     uint8_t *note_buf;          /* buffer for notes */
     size_t note_buf_offset;     /* the writing place in note_buf */
@@ -203,4 +202,42 @@ typedef struct DumpState {
 uint16_t cpu_to_dump16(DumpState *s, uint16_t val);
 uint32_t cpu_to_dump32(DumpState *s, uint32_t val);
 uint64_t cpu_to_dump64(DumpState *s, uint64_t val);
+
+static inline int64_t dump_get_memblock_size(GuestPhysBlock *block, int64_t 
filter_area_start,
+                                             int64_t filter_area_length)
+{
+    int64_t size, left, right;
+
+    /* No filter, return full size */
+    if (!filter_area_length) {
+        return block->target_end - block->target_start;
+    }
+
+    /* calculate the overlapped region. */
+    left = MAX(filter_area_start, block->target_start);
+    right = MIN(filter_area_start + filter_area_length, block->target_end);
+    size = right - left;
+    size = size > 0 ? size : 0;
+
+    return size;
+}
+
+static inline int64_t dump_get_memblock_start(GuestPhysBlock *block, int64_t 
filter_area_start,
+                                  int64_t filter_area_length)
+{
+    if (filter_area_length) {
+        /*
+         * Check if block is within guest memory dump area. If not
+         * go to next one.
+         */
+        if (block->target_start >= filter_area_start + filter_area_length ||
+            block->target_end <= filter_area_start) {
+            return -1;
+        }
+        if (filter_area_start > block->target_start) {
+            return filter_area_start - block->target_start;
+        }
+    }
+    return block->target_start;
+}
 #endif
-- 
2.34.1