1 files changed, 12 insertions, 43 deletions

diff --git a/backends/hostmem-shm.c b/backends/hostmem-shm.c
index 374edc3..f66211a 100644
--- a/backends/hostmem-shm.c
+++ b/backends/hostmem-shm.c
@@ -11,8 +11,9 @@
  */
 
 #include "qemu/osdep.h"
-#include "sysemu/hostmem.h"
+#include "system/hostmem.h"
 #include "qapi/error.h"
+#include "migration/cpr.h"
 
 #define TYPE_MEMORY_BACKEND_SHM "memory-backend-shm"
 
@@ -25,11 +26,9 @@ struct HostMemoryBackendShm {
 static bool
 shm_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
 {
-    g_autoptr(GString) shm_name = g_string_new(NULL);
-    g_autofree char *backend_name = NULL;
+    g_autofree char *backend_name = host_memory_backend_get_name(backend);
     uint32_t ram_flags;
-    int fd, oflag;
-    mode_t mode;
+    int fd = cpr_find_fd(backend_name, 0);
 
     if (!backend->size) {
         error_setg(errp, "can't create shm backend with size 0");
@@ -41,48 +40,18 @@ shm_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
         return false;
     }
 
-    /*
-     * Let's use `mode = 0` because we don't want other processes to open our
-     * memory unless we share the file descriptor with them.
-     */
-    mode = 0;
-    oflag = O_RDWR | O_CREAT | O_EXCL;
-    backend_name = host_memory_backend_get_name(backend);
-
-    /*
-     * Some operating systems allow creating anonymous POSIX shared memory
-     * objects (e.g. FreeBSD provides the SHM_ANON constant), but this is not
-     * defined by POSIX, so let's create a unique name.
-     *
-     * From Linux's shm_open(3) man-page:
-     *   For  portable  use,  a shared  memory  object should be identified
-     *   by a name of the form /somename;"
-     */
-    g_string_printf(shm_name, "/qemu-" FMT_pid "-shm-%s", getpid(),
-                    backend_name);
-
-    fd = shm_open(shm_name->str, oflag, mode);
-    if (fd < 0) {
-        error_setg_errno(errp, errno,
-                         "failed to create POSIX shared memory");
-        return false;
+    if (fd >= 0) {
+        goto have_fd;
     }
 
-    /*
-     * We have the file descriptor, so we no longer need to expose the
-     * POSIX shared memory object. However it will remain allocated as long as
-     * there are file descriptors pointing to it.
-     */
-    shm_unlink(shm_name->str);
-
-    if (ftruncate(fd, backend->size) == -1) {
-        error_setg_errno(errp, errno,
-                         "failed to resize POSIX shared memory to %" PRIu64,
-                         backend->size);
-        close(fd);
+    fd = qemu_shm_alloc(backend->size, errp);
+    if (fd < 0) {
         return false;
     }
+    cpr_save_fd(backend_name, 0, fd);
 
+have_fd:
+    /* Let's do the same as memory-backend-ram,share=on would do. */
     ram_flags = RAM_SHARED;
     ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
 
@@ -100,7 +69,7 @@ shm_backend_instance_init(Object *obj)
 }
 
 static void
-shm_backend_class_init(ObjectClass *oc, void *data)
+shm_backend_class_init(ObjectClass *oc, const void *data)
 {
     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);