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1 /*
2  * Copyright © 2021 Intel Corporation
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice (including the next
12  * paragraph) shall be included in all copies or substantial portions of the
13  * Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21  * IN THE SOFTWARE.
22  */
23 
24 #include "vk_semaphore.h"
25 
26 #include "util/os_time.h"
27 
28 #ifndef _WIN32
29 #include <unistd.h>
30 #endif
31 
32 #include "vk_common_entrypoints.h"
33 #include "vk_device.h"
34 #include "vk_log.h"
35 #include "vk_physical_device.h"
36 #include "vk_util.h"
37 
38 static VkExternalSemaphoreHandleTypeFlags
vk_sync_semaphore_import_types(const struct vk_sync_type * type,VkSemaphoreType semaphore_type)39 vk_sync_semaphore_import_types(const struct vk_sync_type *type,
40                                VkSemaphoreType semaphore_type)
41 {
42    VkExternalSemaphoreHandleTypeFlags handle_types = 0;
43 
44    if (type->import_opaque_fd)
45       handle_types |= VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT;
46 
47    if (type->export_sync_file && semaphore_type == VK_SEMAPHORE_TYPE_BINARY)
48       handle_types |= VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_SYNC_FD_BIT;
49 
50    return handle_types;
51 }
52 
53 static VkExternalSemaphoreHandleTypeFlags
vk_sync_semaphore_export_types(const struct vk_sync_type * type,VkSemaphoreType semaphore_type)54 vk_sync_semaphore_export_types(const struct vk_sync_type *type,
55                                VkSemaphoreType semaphore_type)
56 {
57    VkExternalSemaphoreHandleTypeFlags handle_types = 0;
58 
59    if (type->export_opaque_fd)
60       handle_types |= VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT;
61 
62    if (type->export_sync_file && semaphore_type == VK_SEMAPHORE_TYPE_BINARY)
63       handle_types |= VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_SYNC_FD_BIT;
64 
65    return handle_types;
66 }
67 
68 static VkExternalSemaphoreHandleTypeFlags
vk_sync_semaphore_handle_types(const struct vk_sync_type * type,VkSemaphoreType semaphore_type)69 vk_sync_semaphore_handle_types(const struct vk_sync_type *type,
70                                VkSemaphoreType semaphore_type)
71 {
72    return vk_sync_semaphore_export_types(type, semaphore_type) &
73           vk_sync_semaphore_import_types(type, semaphore_type);
74 }
75 
76 static const struct vk_sync_type *
get_semaphore_sync_type(struct vk_physical_device * pdevice,VkSemaphoreType semaphore_type,VkExternalSemaphoreHandleTypeFlags handle_types)77 get_semaphore_sync_type(struct vk_physical_device *pdevice,
78                         VkSemaphoreType semaphore_type,
79                         VkExternalSemaphoreHandleTypeFlags handle_types)
80 {
81    assert(semaphore_type == VK_SEMAPHORE_TYPE_BINARY ||
82           semaphore_type == VK_SEMAPHORE_TYPE_TIMELINE);
83 
84    enum vk_sync_features req_features = VK_SYNC_FEATURE_GPU_WAIT;
85    if (semaphore_type == VK_SEMAPHORE_TYPE_TIMELINE) {
86       req_features |= VK_SYNC_FEATURE_TIMELINE |
87                       VK_SYNC_FEATURE_CPU_WAIT;
88    } else {
89       req_features |= VK_SYNC_FEATURE_BINARY;
90    }
91 
92    for (const struct vk_sync_type *const *t =
93         pdevice->supported_sync_types; *t; t++) {
94       if (req_features & ~(*t)->features)
95          continue;
96 
97       if (handle_types & ~vk_sync_semaphore_handle_types(*t, semaphore_type))
98          continue;
99 
100       return *t;
101    }
102 
103    return NULL;
104 }
105 
106 static VkSemaphoreType
get_semaphore_type(const void * pNext,uint64_t * initial_value)107 get_semaphore_type(const void *pNext, uint64_t *initial_value)
108 {
109    const VkSemaphoreTypeCreateInfo *type_info =
110       vk_find_struct_const(pNext, SEMAPHORE_TYPE_CREATE_INFO);
111 
112    if (!type_info)
113       return VK_SEMAPHORE_TYPE_BINARY;
114 
115    if (initial_value)
116       *initial_value = type_info->initialValue;
117    return type_info->semaphoreType;
118 }
119 
120 VKAPI_ATTR VkResult VKAPI_CALL
vk_common_CreateSemaphore(VkDevice _device,const VkSemaphoreCreateInfo * pCreateInfo,const VkAllocationCallbacks * pAllocator,VkSemaphore * pSemaphore)121 vk_common_CreateSemaphore(VkDevice _device,
122                           const VkSemaphoreCreateInfo *pCreateInfo,
123                           const VkAllocationCallbacks *pAllocator,
124                           VkSemaphore *pSemaphore)
125 {
126    VK_FROM_HANDLE(vk_device, device, _device);
127    struct vk_semaphore *semaphore;
128 
129    assert(pCreateInfo->sType == VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO);
130 
131    uint64_t initial_value = 0;
132    const VkSemaphoreType semaphore_type =
133       get_semaphore_type(pCreateInfo->pNext, &initial_value);
134 
135    if (semaphore_type == VK_SEMAPHORE_TYPE_TIMELINE)
136       assert(device->timeline_mode != VK_DEVICE_TIMELINE_MODE_NONE);
137 
138    const VkExportSemaphoreCreateInfo *export =
139       vk_find_struct_const(pCreateInfo->pNext, EXPORT_SEMAPHORE_CREATE_INFO);
140    VkExternalSemaphoreHandleTypeFlags handle_types =
141       export ? export->handleTypes : 0;
142 
143    const struct vk_sync_type *sync_type =
144       get_semaphore_sync_type(device->physical, semaphore_type, handle_types);
145    if (sync_type == NULL) {
146       /* We should always be able to get a semaphore type for internal */
147       assert(get_semaphore_sync_type(device->physical, semaphore_type, 0) != NULL);
148       return vk_errorf(device, VK_ERROR_INVALID_EXTERNAL_HANDLE,
149                        "Combination of external handle types is unsupported "
150                        "for VkSemaphore creation.");
151    }
152 
153    /* If the timeline mode is ASSISTED, then any permanent binary semaphore
154     * types need to be able to support move.  We don't require this for
155     * temporary unless that temporary is also used as a semaphore signal
156     * operation which is much trickier to assert early.
157     */
158    if (semaphore_type == VK_SEMAPHORE_TYPE_BINARY &&
159        vk_device_supports_threaded_submit(device))
160       assert(sync_type->move);
161 
162    /* Allocate a vk_semaphore + vk_sync implementation. Because the permanent
163     * field of vk_semaphore is the base field of the vk_sync implementation,
164     * we can make the 2 structures overlap.
165     */
166    size_t size = offsetof(struct vk_semaphore, permanent) + sync_type->size;
167    semaphore = vk_object_zalloc(device, pAllocator, size,
168                                 VK_OBJECT_TYPE_SEMAPHORE);
169    if (semaphore == NULL)
170       return vk_error(device, VK_ERROR_OUT_OF_HOST_MEMORY);
171 
172    semaphore->type = semaphore_type;
173 
174    enum vk_sync_flags sync_flags = 0;
175    if (semaphore_type == VK_SEMAPHORE_TYPE_TIMELINE)
176       sync_flags |= VK_SYNC_IS_TIMELINE;
177    if (handle_types)
178       sync_flags |= VK_SYNC_IS_SHAREABLE;
179 
180    VkResult result = vk_sync_init(device, &semaphore->permanent,
181                                   sync_type, sync_flags, initial_value);
182    if (result != VK_SUCCESS) {
183       vk_object_free(device, pAllocator, semaphore);
184       return result;
185    }
186 
187    *pSemaphore = vk_semaphore_to_handle(semaphore);
188 
189    return VK_SUCCESS;
190 }
191 
192 void
vk_semaphore_reset_temporary(struct vk_device * device,struct vk_semaphore * semaphore)193 vk_semaphore_reset_temporary(struct vk_device *device,
194                              struct vk_semaphore *semaphore)
195 {
196    if (semaphore->temporary == NULL)
197       return;
198 
199    vk_sync_destroy(device, semaphore->temporary);
200    semaphore->temporary = NULL;
201 }
202 
203 VKAPI_ATTR void VKAPI_CALL
vk_common_DestroySemaphore(VkDevice _device,VkSemaphore _semaphore,const VkAllocationCallbacks * pAllocator)204 vk_common_DestroySemaphore(VkDevice _device,
205                            VkSemaphore _semaphore,
206                            const VkAllocationCallbacks *pAllocator)
207 {
208    VK_FROM_HANDLE(vk_device, device, _device);
209    VK_FROM_HANDLE(vk_semaphore, semaphore, _semaphore);
210 
211    if (semaphore == NULL)
212       return;
213 
214    vk_semaphore_reset_temporary(device, semaphore);
215    vk_sync_finish(device, &semaphore->permanent);
216 
217    vk_object_free(device, pAllocator, semaphore);
218 }
219 
220 VKAPI_ATTR void VKAPI_CALL
vk_common_GetPhysicalDeviceExternalSemaphoreProperties(VkPhysicalDevice physicalDevice,const VkPhysicalDeviceExternalSemaphoreInfo * pExternalSemaphoreInfo,VkExternalSemaphoreProperties * pExternalSemaphoreProperties)221 vk_common_GetPhysicalDeviceExternalSemaphoreProperties(
222    VkPhysicalDevice physicalDevice,
223    const VkPhysicalDeviceExternalSemaphoreInfo *pExternalSemaphoreInfo,
224    VkExternalSemaphoreProperties *pExternalSemaphoreProperties)
225 {
226    VK_FROM_HANDLE(vk_physical_device, pdevice, physicalDevice);
227 
228    assert(pExternalSemaphoreInfo->sType ==
229           VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_EXTERNAL_SEMAPHORE_INFO);
230    const VkExternalSemaphoreHandleTypeFlagBits handle_type =
231       pExternalSemaphoreInfo->handleType;
232 
233    const VkSemaphoreType semaphore_type =
234       get_semaphore_type(pExternalSemaphoreInfo->pNext, NULL);
235 
236    const struct vk_sync_type *sync_type =
237       get_semaphore_sync_type(pdevice, semaphore_type, handle_type);
238    if (sync_type == NULL) {
239       pExternalSemaphoreProperties->exportFromImportedHandleTypes = 0;
240       pExternalSemaphoreProperties->compatibleHandleTypes = 0;
241       pExternalSemaphoreProperties->externalSemaphoreFeatures = 0;
242       return;
243    }
244 
245    VkExternalSemaphoreHandleTypeFlagBits import =
246       vk_sync_semaphore_import_types(sync_type, semaphore_type);
247    VkExternalSemaphoreHandleTypeFlagBits export =
248       vk_sync_semaphore_export_types(sync_type, semaphore_type);
249 
250    if (handle_type != VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT) {
251       const struct vk_sync_type *opaque_sync_type =
252          get_semaphore_sync_type(pdevice, semaphore_type,
253                                  VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT);
254 
255       /* If we're a different vk_sync_type than the one selected when only
256        * OPAQUE_FD is set, then we can't import/export OPAQUE_FD.  Put
257        * differently, there can only be one OPAQUE_FD sync type.
258        */
259       if (sync_type != opaque_sync_type) {
260          import &= ~VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT;
261          export &= ~VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT;
262       }
263    }
264 
265    VkExternalSemaphoreHandleTypeFlags compatible = import & export;
266    VkExternalSemaphoreFeatureFlags features = 0;
267    if (handle_type & export)
268       features |= VK_EXTERNAL_SEMAPHORE_FEATURE_EXPORTABLE_BIT;
269    if (handle_type & import)
270       features |= VK_EXTERNAL_SEMAPHORE_FEATURE_IMPORTABLE_BIT;
271 
272    pExternalSemaphoreProperties->exportFromImportedHandleTypes = export;
273    pExternalSemaphoreProperties->compatibleHandleTypes = compatible;
274    pExternalSemaphoreProperties->externalSemaphoreFeatures = features;
275 }
276 
277 VKAPI_ATTR VkResult VKAPI_CALL
vk_common_GetSemaphoreCounterValue(VkDevice _device,VkSemaphore _semaphore,uint64_t * pValue)278 vk_common_GetSemaphoreCounterValue(VkDevice _device,
279                                    VkSemaphore _semaphore,
280                                    uint64_t *pValue)
281 {
282    VK_FROM_HANDLE(vk_device, device, _device);
283    VK_FROM_HANDLE(vk_semaphore, semaphore, _semaphore);
284 
285    if (vk_device_is_lost(device))
286       return VK_ERROR_DEVICE_LOST;
287 
288    struct vk_sync *sync = vk_semaphore_get_active_sync(semaphore);
289    return vk_sync_get_value(device, sync, pValue);
290 }
291 
292 VKAPI_ATTR VkResult VKAPI_CALL
vk_common_WaitSemaphores(VkDevice _device,const VkSemaphoreWaitInfo * pWaitInfo,uint64_t timeout)293 vk_common_WaitSemaphores(VkDevice _device,
294                          const VkSemaphoreWaitInfo *pWaitInfo,
295                          uint64_t timeout)
296 {
297    VK_FROM_HANDLE(vk_device, device, _device);
298 
299    if (vk_device_is_lost(device))
300       return VK_ERROR_DEVICE_LOST;
301 
302    if (pWaitInfo->semaphoreCount == 0)
303       return VK_SUCCESS;
304 
305    uint64_t abs_timeout_ns = os_time_get_absolute_timeout(timeout);
306 
307    const uint32_t wait_count = pWaitInfo->semaphoreCount;
308    STACK_ARRAY(struct vk_sync_wait, waits, pWaitInfo->semaphoreCount);
309 
310    for (uint32_t i = 0; i < wait_count; i++) {
311       VK_FROM_HANDLE(vk_semaphore, semaphore, pWaitInfo->pSemaphores[i]);
312       assert(semaphore->type == VK_SEMAPHORE_TYPE_TIMELINE);
313 
314       waits[i] = (struct vk_sync_wait) {
315          .sync = vk_semaphore_get_active_sync(semaphore),
316          .stage_mask = ~(VkPipelineStageFlags2)0,
317          .wait_value = pWaitInfo->pValues[i],
318       };
319    }
320 
321    enum vk_sync_wait_flags wait_flags = VK_SYNC_WAIT_COMPLETE;
322    if (pWaitInfo->flags & VK_SEMAPHORE_WAIT_ANY_BIT)
323       wait_flags |= VK_SYNC_WAIT_ANY;
324 
325    VkResult result = vk_sync_wait_many(device, wait_count, waits,
326                                        wait_flags, abs_timeout_ns);
327 
328    STACK_ARRAY_FINISH(waits);
329 
330    VkResult device_status = vk_device_check_status(device);
331    if (device_status != VK_SUCCESS)
332       return device_status;
333 
334    return result;
335 }
336 
337 VKAPI_ATTR VkResult VKAPI_CALL
vk_common_SignalSemaphore(VkDevice _device,const VkSemaphoreSignalInfo * pSignalInfo)338 vk_common_SignalSemaphore(VkDevice _device,
339                           const VkSemaphoreSignalInfo *pSignalInfo)
340 {
341    VK_FROM_HANDLE(vk_device, device, _device);
342    VK_FROM_HANDLE(vk_semaphore, semaphore, pSignalInfo->semaphore);
343    struct vk_sync *sync = vk_semaphore_get_active_sync(semaphore);
344    VkResult result;
345 
346    /* From the Vulkan 1.2.194 spec:
347     *
348     *    UID-VkSemaphoreSignalInfo-semaphore-03257
349     *
350     *    "semaphore must have been created with a VkSemaphoreType of
351     *    VK_SEMAPHORE_TYPE_TIMELINE."
352     */
353    assert(semaphore->type == VK_SEMAPHORE_TYPE_TIMELINE);
354 
355    /* From the Vulkan 1.2.194 spec:
356     *
357     *    VUID-VkSemaphoreSignalInfo-value-03258
358     *
359     *    "value must have a value greater than the current value of the
360     *    semaphore"
361     *
362     * Since 0 is the lowest possible semaphore timeline value, we can assert
363     * that a non-zero signal value is provided.
364     */
365    if (unlikely(pSignalInfo->value == 0)) {
366       return vk_device_set_lost(device,
367          "Tried to signal a timeline with value 0");
368    }
369 
370    result = vk_sync_signal(device, sync, pSignalInfo->value);
371    if (unlikely(result != VK_SUCCESS))
372       return result;
373 
374    if (device->submit_mode == VK_QUEUE_SUBMIT_MODE_DEFERRED) {
375       result = vk_device_flush(device);
376       if (unlikely(result != VK_SUCCESS))
377          return result;
378    }
379 
380    return VK_SUCCESS;
381 }
382 
383 #ifndef _WIN32
384 
385 VKAPI_ATTR VkResult VKAPI_CALL
vk_common_ImportSemaphoreFdKHR(VkDevice _device,const VkImportSemaphoreFdInfoKHR * pImportSemaphoreFdInfo)386 vk_common_ImportSemaphoreFdKHR(VkDevice _device,
387                                const VkImportSemaphoreFdInfoKHR *pImportSemaphoreFdInfo)
388 {
389    VK_FROM_HANDLE(vk_device, device, _device);
390    VK_FROM_HANDLE(vk_semaphore, semaphore, pImportSemaphoreFdInfo->semaphore);
391 
392    assert(pImportSemaphoreFdInfo->sType ==
393           VK_STRUCTURE_TYPE_IMPORT_SEMAPHORE_FD_INFO_KHR);
394 
395    const int fd = pImportSemaphoreFdInfo->fd;
396    const VkExternalSemaphoreHandleTypeFlagBits handle_type =
397       pImportSemaphoreFdInfo->handleType;
398 
399    struct vk_sync *temporary = NULL, *sync;
400    if (pImportSemaphoreFdInfo->flags & VK_SEMAPHORE_IMPORT_TEMPORARY_BIT) {
401       /* From the Vulkan 1.2.194 spec:
402        *
403        *    VUID-VkImportSemaphoreFdInfoKHR-flags-03323
404        *
405        *    "If flags contains VK_SEMAPHORE_IMPORT_TEMPORARY_BIT, the
406        *    VkSemaphoreTypeCreateInfo::semaphoreType field of the semaphore
407        *    from which handle or name was exported must not be
408        *    VK_SEMAPHORE_TYPE_TIMELINE"
409        */
410       if (unlikely(semaphore->type == VK_SEMAPHORE_TYPE_TIMELINE)) {
411          return vk_errorf(device, VK_ERROR_UNKNOWN,
412                           "Cannot temporarily import into a timeline "
413                           "semaphore");
414       }
415 
416       const struct vk_sync_type *sync_type =
417          get_semaphore_sync_type(device->physical, semaphore->type, handle_type);
418 
419       VkResult result = vk_sync_create(device, sync_type, 0 /* flags */,
420                                        0 /* initial_value */, &temporary);
421       if (result != VK_SUCCESS)
422          return result;
423 
424       sync = temporary;
425    } else {
426       sync = &semaphore->permanent;
427    }
428    assert(handle_type &
429           vk_sync_semaphore_handle_types(sync->type, semaphore->type));
430 
431    VkResult result;
432    switch (pImportSemaphoreFdInfo->handleType) {
433    case VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT:
434       result = vk_sync_import_opaque_fd(device, sync, fd);
435       break;
436 
437    case VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_SYNC_FD_BIT:
438       result = vk_sync_import_sync_file(device, sync, fd);
439       break;
440 
441    default:
442       result = vk_error(semaphore, VK_ERROR_INVALID_EXTERNAL_HANDLE);
443    }
444 
445    if (result != VK_SUCCESS) {
446       if (temporary != NULL)
447          vk_sync_destroy(device, temporary);
448       return result;
449    }
450 
451    /* From the Vulkan 1.2.194 spec:
452     *
453     *    "Importing a semaphore payload from a file descriptor transfers
454     *    ownership of the file descriptor from the application to the Vulkan
455     *    implementation. The application must not perform any operations on
456     *    the file descriptor after a successful import."
457     *
458     * If the import fails, we leave the file descriptor open.
459     */
460    if (fd != -1)
461       close(fd);
462 
463    /* From a spec correctness point of view, we could probably replace the
464     * semaphore's temporary payload with the new vk_sync at the top.  However,
465     * we choose to be nice to applications and only replace the semaphore if
466     * the import succeeded.
467     */
468    if (temporary) {
469       vk_semaphore_reset_temporary(device, semaphore);
470       semaphore->temporary = temporary;
471    }
472 
473    return VK_SUCCESS;
474 }
475 
476 VKAPI_ATTR VkResult VKAPI_CALL
vk_common_GetSemaphoreFdKHR(VkDevice _device,const VkSemaphoreGetFdInfoKHR * pGetFdInfo,int * pFd)477 vk_common_GetSemaphoreFdKHR(VkDevice _device,
478                             const VkSemaphoreGetFdInfoKHR *pGetFdInfo,
479                             int *pFd)
480 {
481    VK_FROM_HANDLE(vk_device, device, _device);
482    VK_FROM_HANDLE(vk_semaphore, semaphore, pGetFdInfo->semaphore);
483 
484    assert(pGetFdInfo->sType == VK_STRUCTURE_TYPE_SEMAPHORE_GET_FD_INFO_KHR);
485 
486    struct vk_sync *sync = vk_semaphore_get_active_sync(semaphore);
487 
488    VkResult result;
489    switch (pGetFdInfo->handleType) {
490    case VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT:
491       result = vk_sync_export_opaque_fd(device, sync, pFd);
492       if (result != VK_SUCCESS)
493          return result;
494       break;
495 
496    case VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_SYNC_FD_BIT:
497       /* From the Vulkan 1.2.194 spec:
498        *
499        *    VUID-VkSemaphoreGetFdInfoKHR-handleType-03253
500        *
501        *    "If handleType refers to a handle type with copy payload
502        *    transference semantics, semaphore must have been created with a
503        *    VkSemaphoreType of VK_SEMAPHORE_TYPE_BINARY."
504        */
505       if (unlikely(semaphore->type != VK_SEMAPHORE_TYPE_BINARY)) {
506          return vk_errorf(device, VK_ERROR_INVALID_EXTERNAL_HANDLE,
507                           "Cannot export a timeline semaphore as SYNC_FD");
508       }
509 
510       /* From the Vulkan 1.2.194 spec:
511        *    VUID-VkSemaphoreGetFdInfoKHR-handleType-03254
512        *
513        *    "If handleType refers to a handle type with copy payload
514        *    transference semantics, semaphore must have an associated
515        *    semaphore signal operation that has been submitted for execution
516        *    and any semaphore signal operations on which it depends (if any)
517        *    must have also been submitted for execution."
518        *
519        * If we have real timelines, it's possible that the time point doesn't
520        * exist yet and is waiting for one of our submit threads to trigger.
521        * However, thanks to the above bit of spec text, that wait should never
522        * block for long.
523        */
524       if (vk_device_supports_threaded_submit(device)) {
525          result = vk_sync_wait(device, sync, 0,
526                                VK_SYNC_WAIT_PENDING,
527                                UINT64_MAX);
528          if (unlikely(result != VK_SUCCESS))
529             return result;
530       }
531 
532       result = vk_sync_export_sync_file(device, sync, pFd);
533       if (unlikely(result != VK_SUCCESS))
534          return result;
535 
536       /* From the Vulkan 1.2.194 spec:
537        *
538        *    "Export operations have the same transference as the specified
539        *    handle type’s import operations. Additionally, exporting a
540        *    semaphore payload to a handle with copy transference has the same
541        *    side effects on the source semaphore’s payload as executing a
542        *    semaphore wait operation."
543        *
544        * In other words, exporting a sync file also resets the semaphore.  We
545        * only care about this for the permanent payload because the temporary
546        * payload will be destroyed below.
547        */
548       if (sync == &semaphore->permanent) {
549          result = vk_sync_reset(device, sync);
550          if (unlikely(result != VK_SUCCESS))
551             return result;
552       }
553       break;
554 
555    default:
556       unreachable("Invalid semaphore export handle type");
557    }
558 
559    /* From the Vulkan 1.2.194 spec:
560     *
561     *    "Export operations have the same transference as the specified
562     *    handle type’s import operations. [...] If the semaphore was using
563     *    a temporarily imported payload, the semaphore’s prior permanent
564     *    payload will be restored."
565     */
566    vk_semaphore_reset_temporary(device, semaphore);
567 
568    return VK_SUCCESS;
569 }
570 
571 #endif /* !defined(_WIN32) */
572