Re: [RFC 13/26] plugins/amdgpu: Consolidate vm_info collection

(Re-sending, hopefully without html content)

This ioctl shouldn't ever need more than two calls (the first call should give the right size for the second) but this is cleaner.
Nitpick: criu seems to use "while (1)" more than "for (;;)". Could this be changed here?

With that change, this is

Reviewed-By: David Francis <[email protected]>

________________________________________
From: Tvrtko Ursulin <[email protected]>
Sent: Friday, February 20, 2026 7:05 AM
To: [email protected]
Cc: Francis, David; Tvrtko Ursulin
Subject: [RFC 13/26] plugins/amdgpu: Consolidate vm_info collection

Instead of open coding the same ioctl twice we can put it in a loop from
which we break out once we have allocated enough space for all objects.

While at it we add error handling for the memory allocation.

Signed-off-by: Tvrtko Ursulin <[email protected]>
---
 plugins/amdgpu/amdgpu_plugin_drm.c | 47 ++++++++++++++++--------------
 1 file changed, 25 insertions(+), 22 deletions(-)

diff --git a/plugins/amdgpu/amdgpu_plugin_drm.c b/plugins/amdgpu/amdgpu_plugin_drm.c
index 9df755450dc9..baa560537813 100644
--- a/plugins/amdgpu/amdgpu_plugin_drm.c
+++ b/plugins/amdgpu/amdgpu_plugin_drm.c
@@ -302,8 +302,7 @@ int amdgpu_plugin_drm_dump_file(int fd, int id, struct stat *drm)

        for (int i = 0; i < num_bos; i++) {
                int num_vm_entries = 8;
-               struct drm_amdgpu_gem_vm_entry *vm_info_entries;
-               struct drm_amdgpu_gem_op vm_info_args = { 0 };
+               struct drm_amdgpu_gem_vm_entry *vm_info_entries = NULL;
                DrmBoEntry *boinfo = rd->bo_entries[i];
                struct drm_amdgpu_gem_list_handles_entry handle_entry = list_handles_entries[i];
                union drm_amdgpu_gem_mmap mmap_args = { 0 };
@@ -333,32 +332,36 @@ int amdgpu_plugin_drm_dump_file(int fd, int id, struct stat *drm)

                boinfo->offset = mmap_args.out.addr_ptr;

-               vm_info_entries = xzalloc(sizeof(struct drm_amdgpu_gem_vm_entry) * num_vm_entries);
-               vm_info_args.handle = handle_entry.gem_handle;
-               vm_info_args.num_entries = num_vm_entries;
-               vm_info_args.value = (uintptr_t)vm_info_entries;
-               vm_info_args.op = AMDGPU_GEM_OP_GET_MAPPING_INFO;
-               ret = drmIoctl(fd, DRM_IOCTL_AMDGPU_GEM_OP, &vm_info_args);
-               if (ret) {
-                       pr_perror("Failed to call vm info ioctl");
-                       goto exit;
-               }
+               for (;;) {
+                       struct drm_amdgpu_gem_op vm_info_args = {
+                               .handle = handle_entry.gem_handle,
+                               .num_entries = num_vm_entries,
+                               .op = AMDGPU_GEM_OP_GET_MAPPING_INFO,
+                       };
+
+                       if (vm_info_entries)
+                               xfree(vm_info_entries);
+                       vm_info_entries = xzalloc(sizeof(*vm_info_entries) *
+                                                 num_vm_entries);
+                       if (!vm_info_entries) {
+                               ret = -ENOMEM;
+                               goto exit;
+                       }

-               if (vm_info_args.num_entries > num_vm_entries) {
-                       num_vm_entries = vm_info_args.num_entries;
-                       xfree(vm_info_entries);
-                       vm_info_entries = xzalloc(sizeof(struct drm_amdgpu_gem_vm_entry) * num_vm_entries);
-                       vm_info_args.handle = handle_entry.gem_handle;
-                       vm_info_args.num_entries = num_vm_entries;
                        vm_info_args.value = (uintptr_t)vm_info_entries;
-                       vm_info_args.op = AMDGPU_GEM_OP_GET_MAPPING_INFO;
-                       ret = drmIoctl(fd, DRM_IOCTL_AMDGPU_GEM_OP, &vm_info_args);
+                       ret = drmIoctl(fd, DRM_IOCTL_AMDGPU_GEM_OP,
+                                      &vm_info_args);
                        if (ret) {
                                pr_perror("Failed to call vm info ioctl");
                                goto exit;
                        }
-               } else {
-                       num_vm_entries = vm_info_args.num_entries;
+
+                       if (vm_info_args.num_entries <= num_vm_entries) {
+                               num_vm_entries = vm_info_args.num_entries;
+                               break;
+                       } else {
+                               num_vm_entries = vm_info_args.num_entries;
+                       }
                }

                boinfo->num_of_vms = num_vm_entries;
--
2.52.0