From: jsg <jsg@openbsd.org>
Date: Tue, 21 Nov 2023 02:23:24 +0000 (+0000)
Subject: drm/amdkfd: fix some race conditions in vram buffer alloc/free of svm code
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=eeb918668a86128038a248a66aea50925f8e85fe;p=openbsd

drm/amdkfd: fix some race conditions in vram buffer alloc/free of svm code

From Xiaogang Chen
9eae81af9243aabb75bdf638fd773cdee0907f92 in linux-6.1.y/6.1.63
7bfaa160caed8192f8262c4638f552cad94bcf5a in mainline linux
---

diff --git a/sys/dev/pci/drm/amd/amdkfd/kfd_svm.c b/sys/dev/pci/drm/amd/amdkfd/kfd_svm.c
index 63feea08904..d7e758c86a0 100644
--- a/sys/dev/pci/drm/amd/amdkfd/kfd_svm.c
+++ b/sys/dev/pci/drm/amd/amdkfd/kfd_svm.c
@@ -487,11 +487,11 @@ svm_range_validate_svm_bo(struct amdgpu_device *adev, struct svm_range *prange)
 
 	/* We need a new svm_bo. Spin-loop to wait for concurrent
 	 * svm_range_bo_release to finish removing this range from
-	 * its range list. After this, it is safe to reuse the
-	 * svm_bo pointer and svm_bo_list head.
+	 * its range list and set prange->svm_bo to null. After this,
+	 * it is safe to reuse the svm_bo pointer and svm_bo_list head.
 	 */
-	while (!list_empty_careful(&prange->svm_bo_list))
-		;
+	while (!list_empty_careful(&prange->svm_bo_list) || prange->svm_bo)
+		cond_resched();
 
 	return false;
 }