exec: convert ram_list to QLIST

QLIST has RCU-friendly primitives, so switch to it.

Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Mike Day <ncmike@ncultra.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 30 insertions, 22 deletions

diff --git a/exec.c b/exec.c
index 2b6ee55218..a7c2b92d0a 100644
--- a/exec.c
+++ b/exec.c
@@ -58,7 +58,7 @@
 #if !defined(CONFIG_USER_ONLY)
 static bool in_migration;
 
-RAMList ram_list = { .blocks = QTAILQ_HEAD_INITIALIZER(ram_list.blocks) };
+RAMList ram_list = { .blocks = QLIST_HEAD_INITIALIZER(ram_list.blocks) };
 
 static MemoryRegion *system_memory;
 static MemoryRegion *system_io;
@@ -815,7 +815,7 @@ static RAMBlock *qemu_get_ram_block(ram_addr_t addr)
     if (block && addr - block->offset < block->max_length) {
         goto found;
     }
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         if (addr - block->offset < block->max_length) {
             goto found;
         }
@@ -1197,15 +1197,16 @@ static ram_addr_t find_ram_offset(ram_addr_t size)
 
     assert(size != 0); /* it would hand out same offset multiple times */
 
-    if (QTAILQ_EMPTY(&ram_list.blocks))
+    if (QLIST_EMPTY(&ram_list.blocks)) {
         return 0;
+    }
 
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         ram_addr_t end, next = RAM_ADDR_MAX;
 
         end = block->offset + block->max_length;
 
-        QTAILQ_FOREACH(next_block, &ram_list.blocks, next) {
+        QLIST_FOREACH(next_block, &ram_list.blocks, next) {
             if (next_block->offset >= end) {
                 next = MIN(next, next_block->offset);
             }
@@ -1230,9 +1231,9 @@ ram_addr_t last_ram_offset(void)
     RAMBlock *block;
     ram_addr_t last = 0;
 
-    QTAILQ_FOREACH(block, &ram_list.blocks, next)
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         last = MAX(last, block->offset + block->max_length);
-
+    }
     return last;
 }
 
@@ -1256,7 +1257,7 @@ static RAMBlock *find_ram_block(ram_addr_t addr)
 {
     RAMBlock *block;
 
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         if (block->offset == addr) {
             return block;
         }
@@ -1284,7 +1285,7 @@ void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev)
     pstrcat(new_block->idstr, sizeof(new_block->idstr), name);
 
     qemu_mutex_lock_ramlist();
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         if (block != new_block && !strcmp(block->idstr, new_block->idstr)) {
             fprintf(stderr, "RAMBlock \"%s\" already registered, abort!\n",
                     new_block->idstr);
@@ -1366,6 +1367,7 @@ int qemu_ram_resize(ram_addr_t base, ram_addr_t newsize, Error **errp)
 static ram_addr_t ram_block_add(RAMBlock *new_block, Error **errp)
 {
     RAMBlock *block;
+    RAMBlock *last_block = NULL;
     ram_addr_t old_ram_size, new_ram_size;
 
     old_ram_size = last_ram_offset() >> TARGET_PAGE_BITS;
@@ -1392,16 +1394,22 @@ static ram_addr_t ram_block_add(RAMBlock *new_block, Error **errp)
         }
     }
 
-    /* Keep the list sorted from biggest to smallest block.  */
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    /* Keep the list sorted from biggest to smallest block.  Unlike QTAILQ,
+     * QLIST (which has an RCU-friendly variant) does not have insertion at
+     * tail, so save the last element in last_block.
+     */
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
+        last_block = block;
         if (block->max_length < new_block->max_length) {
             break;
         }
     }
     if (block) {
-        QTAILQ_INSERT_BEFORE(block, new_block, next);
-    } else {
-        QTAILQ_INSERT_TAIL(&ram_list.blocks, new_block, next);
+        QLIST_INSERT_BEFORE(block, new_block, next);
+    } else if (last_block) {
+        QLIST_INSERT_AFTER(last_block, new_block, next);
+    } else { /* list is empty */
+        QLIST_INSERT_HEAD(&ram_list.blocks, new_block, next);
     }
     ram_list.mru_block = NULL;
 
@@ -1546,9 +1554,9 @@ void qemu_ram_free_from_ptr(ram_addr_t addr)
 
     /* This assumes the iothread lock is taken here too.  */
     qemu_mutex_lock_ramlist();
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         if (addr == block->offset) {
-            QTAILQ_REMOVE(&ram_list.blocks, block, next);
+            QLIST_REMOVE(block, next);
             ram_list.mru_block = NULL;
             ram_list.version++;
             g_free_rcu(block, rcu);
@@ -1582,9 +1590,9 @@ void qemu_ram_free(ram_addr_t addr)
 
     /* This assumes the iothread lock is taken here too.  */
     qemu_mutex_lock_ramlist();
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         if (addr == block->offset) {
-            QTAILQ_REMOVE(&ram_list.blocks, block, next);
+            QLIST_REMOVE(block, next);
             ram_list.mru_block = NULL;
             ram_list.version++;
             call_rcu(block, reclaim_ramblock, rcu);
@@ -1602,7 +1610,7 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length)
     int flags;
     void *area, *vaddr;
 
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         offset = addr - block->offset;
         if (offset < block->max_length) {
             vaddr = ramblock_ptr(block, offset);
@@ -1707,7 +1715,7 @@ static void *qemu_ram_ptr_length(ram_addr_t addr, hwaddr *size)
         return xen_map_cache(addr, *size, 1);
     } else {
         RAMBlock *block;
-        QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+        QLIST_FOREACH(block, &ram_list.blocks, next) {
             if (addr - block->offset < block->max_length) {
                 if (addr - block->offset + *size > block->max_length)
                     *size = block->max_length - addr + block->offset;
@@ -1747,7 +1755,7 @@ MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
         goto found;
     }
 
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         /* This case append when the block is not mapped. */
         if (block->host == NULL) {
             continue;
@@ -3019,7 +3027,7 @@ void qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque)
 {
     RAMBlock *block;
 
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
         func(block->host, block->offset, block->used_length, opaque);
     }
 }