[Qemu-devel] [RFC PATCH v4 2/5] ramlist mutex

[Umesh Deshpande]

ramlist mutex is implemented to protect the RAMBlock list traversal in the
migration thread from their addition/removal from the iothread.

Signed-off-by: Umesh Deshpande <address@hidden>
---
 cpu-all.h     |    2 ++
 exec.c        |   19 +++++++++++++++++++
 qemu-common.h |    2 ++
 3 files changed, 23 insertions(+), 0 deletions(-)

diff --git a/cpu-all.h b/cpu-all.h
index 6b217a2..eab9803 100644
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -21,6 +21,7 @@
 
 #include "qemu-common.h"
 #include "cpu-common.h"
+#include "qemu-thread.h"
 
 /* some important defines:
  *
@@ -932,6 +933,7 @@ typedef struct RAMBlock {
 } RAMBlock;
 
 typedef struct RAMList {
+    QemuMutex mutex;
     uint8_t *phys_dirty;
     QLIST_HEAD(ram, RAMBlock) blocks;
     QLIST_HEAD(, RAMBlock) blocks_mru;
diff --git a/exec.c b/exec.c
index c5c247c..404d8ea 100644
--- a/exec.c
+++ b/exec.c
@@ -582,6 +582,7 @@ void cpu_exec_init_all(unsigned long tb_size)
     code_gen_alloc(tb_size);
     code_gen_ptr = code_gen_buffer;
     page_init();
+    qemu_mutex_init(&ram_list.mutex);
 #if !defined(CONFIG_USER_ONLY)
     io_mem_init();
 #endif
@@ -2802,6 +2803,16 @@ static long gethugepagesize(const char *path)
     return fs.f_bsize;
 }
 
+void qemu_mutex_lock_ramlist(void)
+{
+    qemu_mutex_lock(&ram_list.mutex);
+}
+
+void qemu_mutex_unlock_ramlist(void)
+{
+    qemu_mutex_unlock(&ram_list.mutex);
+}
+
 static void *file_ram_alloc(RAMBlock *block,
                             ram_addr_t memory,
                             const char *path)
@@ -2976,6 +2987,8 @@ ram_addr_t qemu_ram_alloc_from_ptr(DeviceState *dev, 
const char *name,
     }
     new_block->length = size;
 
+    qemu_mutex_lock_ramlist();
+
     QLIST_INSERT_HEAD(&ram_list.blocks, new_block, next);
     QLIST_INSERT_HEAD(&ram_list.blocks_mru, new_block, next_mru);
 
@@ -2984,6 +2997,8 @@ ram_addr_t qemu_ram_alloc_from_ptr(DeviceState *dev, 
const char *name,
     memset(ram_list.phys_dirty + (new_block->offset >> TARGET_PAGE_BITS),
            0xff, size >> TARGET_PAGE_BITS);
 
+    qemu_mutex_unlock_ramlist();
+
     if (kvm_enabled())
         kvm_setup_guest_memory(new_block->host, size);
 
@@ -3001,8 +3016,10 @@ void qemu_ram_free_from_ptr(ram_addr_t addr)
 
     QLIST_FOREACH(block, &ram_list.blocks, next) {
         if (addr == block->offset) {
+            qemu_mutex_lock_ramlist();
             QLIST_REMOVE(block, next);
             QLIST_REMOVE(block, next_mru);
+            qemu_mutex_unlock_ramlist();
             qemu_free(block);
             return;
         }
@@ -3015,8 +3032,10 @@ void qemu_ram_free(ram_addr_t addr)
 
     QLIST_FOREACH(block, &ram_list.blocks, next) {
         if (addr == block->offset) {
+            qemu_mutex_lock_ramlist();
             QLIST_REMOVE(block, next);
             QLIST_REMOVE(block, next_mru);
+            qemu_mutex_unlock_ramlist();
             if (block->flags & RAM_PREALLOC_MASK) {
                 ;
             } else if (mem_path) {
diff --git a/qemu-common.h b/qemu-common.h
index abd7a75..b802883 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -212,6 +212,8 @@ char *qemu_strndup(const char *str, size_t size);
 
 void qemu_mutex_lock_iothread(void);
 void qemu_mutex_unlock_iothread(void);
+void qemu_mutex_lock_ramlist(void);
+void qemu_mutex_unlock_ramlist(void);
 
 int qemu_open(const char *name, int flags, ...);
 ssize_t qemu_write_full(int fd, const void *buf, size_t count)
-- 
1.7.4.1